Model Boat Mayhem

Masterclasses => CERVIA Tug Build => Topic started by: John W E on December 28, 2007, 12:33:09 pm

Title: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:33:09 pm
SECOND PLAN BUILD TUG CERVIA

The plan we wish to describe and build from is another plan from the Model Boats magazine plan book.   The plans were drawn by a well respected draughtsman and modeller, some of us regard this gentleman as ‘the modelling God’ Mr Vic Smeed.  The Plan is of the tug ‘Cervia’ drawn to the scale of 1/48 giving a hull length of 28 inches and a beam of 6 ¼ inches.  Although the plans are graded 3 star (and there is a caption saying Not for beginners) with a little help and a little bit of understanding, I believe any with a reasonable amount of knowledge of handling tools, stands a fair chance.

As a modeller gains experience, he also gains originality; meaning he has his own way of doing things.   This becomes unique to the modeller; he may see in a book or on the web a method of making an article.  He will adapt this method to suit himself.  The reason I say this – the way I describe the plans and the way I proceed and build the model, is my method of working – so remember DO IT YOUR WAY if that suits you.  O0
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:35:37 pm
THE PLAN

In photographs 1 and 2 hopefully you will be able to make out the side profile of the tug and also smaller drawings around showing close up of mast, funnel, radar and so forth. 

There are NO building instructions whatsoever. 

There is no suggested material list.

This we have to work out for ourselves;  ;D  so let us take the drawing, as I have said in photograph 1 there is a side profile of the tug and if you notice the hull of the tug has some bonny squiggly lines on.   Some straight lines drawn through it and also some vertical lines drawn through it; now, for the purpose of this build;

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:37:28 pm
The vertical lines that go through the hull from the keel up to the deck are going to become the position of our frames or ribs.   I am unsure whether you will be able to make out on the photographs if you can make out the numbers; they are numbered ¼ at the bow proceeding to ½ then 1, 2 proceeding onwards to 5, 5½ finishing at 6½ at the stern.   

So, we can take it that the hull is divided into 10 frames.   Now, if we look at the 2nd photograph which should be the plan view of the tug which is in full, and, underneath the plan view of the full tug there is a line plan view. 

This, again, shows vertical lines drawn from the keel which are set at 90º to the keel.  There are also lines drawn parallel to the keel and we will call them buttock lines.

Also, radius (curved lines) drawn from the keel and we will call these water lines.   We will not refer to these lines any further, as this will only cloud the issue.

To the right hand side of the plan, you will see a frame drawing; these are half frame drawings; and, this is the information that is important to us.  But, before we get too deeply involved in this, there are one or two pieces of information which we need to satisfy ourselves with:-

1.   What materials are we going to construct the hull from;

2.   What motive power are we going to put into the tug;

So then, to answer the first question – we are proposing to build this plank on frame using 6mm Five-ply plywood (meaning there are 5 layers of veneer to make up this plywood).   We are also going to use Obechi planking strips, followed by a layer of fibre glass tissue coated with polyester resin.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:39:55 pm
The next question then, motive power, we are looking at a 540 sized motor, driving through a 2:1 belt drive gear box.  Along with a 6 volt 8 amp per hour battery or, a 6 volt, 4 amp power battery these should give us ample time on the water.  ;D  In the next photograph you will see I am checking to ensure I can place the batteries into the hull.  You can see there is a battery put on top of the plan and either side of the battery, there are arrows – one red and one black.  These arrows point to the edge of the superstructure.   This is where the opening in the hull will be for access – underneath the main superstructure.

At this stage, I have already decided that the whole superstructure from bridge to engine room hatch will lift off in one, giving me adequate access to the inside of the hull.

Now we are reasonably happy that we can put stuff inside the hull, and we have a rough idea whereabouts we are going to place stuff, remembering on displacement type hulls such as tugs, it is best to keep the heavy weights such as batteries as low down as possible and as near to the centre of the model as we can get.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:41:54 pm
We now move on to the ‘nitty gritty’.  We take a 2nd look at the view of the frames and what I actually did here was photocopied them.   While I photocopied them, I also reduced the size of them by 2mm.   This was to cater for the thickness of the planks and the fibre glass.    If we did not reduce this, it would mean that our finished hull would be 2-3 mm wider than the actual plan.   Now, photocopied and reduced by 2mm.

The next stage is, to set the frame drawing which you have photocopied up onto a small board.  I use a piece of plywood ½ inch thick slightly larger than the A4 size.   The first stage I do is to draw a centre line all the way through the frames – note on the left hand side on this particular drawing is the view of the bow looking towards the stern and of half frames.   On the right hand side of the centre line there are the line drawings of the stern looking towards the bow.

Next draw a line at right angles through the centre line; roughly one inch above the tallest frame.  This line represents the building board and you will see the two lines arrowed.   Now, the first stage is to start and trace as before place the tracing paper over the top of the drawing and secure it in place with either drawing pins or masking tape which I use.  The first thing I did was to trace the centre line followed by the line which represents the building board.   

Once these have been traced, I move on to trace out the frame number ¼ If you note I only trace up to deck level.  Then, I add on two vertical lines from the deck level, up towards the building board line.  These can be of any width apart which you can be happy with, I picked 1 inch apart for these particular lines and these will eventually become supports to hold the frame onto the building board.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:44:41 pm
Once the hull has been finished these ‘legs’ as we will call them, will be cut off.   I only trace one side of the frame – and then flip the tracing paper over and repeat the operation for the next frame on the opposite side to the first frame I have drawn.   Again, drawing in my centre line first of all followed by my building board line; each half frame is drawn out individually along with its own centre line and own building board.

When we get towards the stern we have to take note because we have to measure up and begin to put a centre line in our frames which corresponds with the centre line of the propeller shaft.   Once we have all of our tracings of the frame, we then move on to trace the bow, the keel and the stern profile.   

On this particular model, you will note that she has what is known as a ‘plating rebate line’.  She also has a square keel which runs all the way around the centre.   I have marked this with two arrows on the photograph.   When I trace my keel profile, I use the inner line as the keel.  Also note; I do not trace the rudder or the propeller frame; I then move on (once I have traced the bow and so forth) to copying our tracings onto the material.   As I have said, the material I am using is modelling plywood of five-ply 6mm thickness. Or, if you are ‘old fashioned’ just like me a good old ¼ of an inch.   The procedure I use to copy trace onto the material is:

First of all – begin by drawing a centre line; adequate distance in from both edges of the plywood material to take the full frame.  Then, place the tracing so that the centre line on the tracing lines up with the centre line you have drawn.   Secure the tracing paper down so it does not move and ensure that the two centre lines do not move apart.  After checking; draw over the line on your tracing which represents the baseboard.    Now trace one side of your frame in, then flip the tracing paper over so that the centre line lines up again, along with your baseboard line and also checking that the half frame traced on your tracing paper matches up with the lines you have traced on the plywood.   Trace the other side of the frame ensuring that you have not omitted to trace the support legs in.   Most of all NUMBER IT so you will know what frame it is.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:49:06 pm
Carry on with this procedure until you have done all the frames, as per photograph.   Once we are happy and we have all the frames traced, trace your keel onto the plywood; ensuring that you mark where the frames actually locate onto the keel.  At this stage you will note that the keel has no thickness, no depth, the frames have no notches drawn on for where they locate onto the keel or where there are any deck stringers.  This is done at the next stage.   

To determine the thickness of the keel or how tall the keel is, will depend on what size model you are building.    We don’t want the keel too thin, where it will not stand us applying pressure when we plank without it snapping, or, we do not want it too thick/tall shall we say that it starts to interfere with the centre of gravity when we put batteries in etc., when we have finished the model.

On this particular model, with it only being 28 inches long, I have made the average height/thickness of the keel ¾ inch or roughly 19mm.

So, we will begin marking the notches into the keel; for the frames.    Normally, if the keel is 19mm thick/tall, we will make the notch 10mm deep, or, half the height of the keel.  The other thing to remember is where we have marked our positions of the keel – half the frames will face towards the bow and half the frames will face towards the stern.   The meaning of this is we draw the position of the frame on the keel and the thickness of the frame faces the bow; right up until the centre frame and in our case it is frame number 3 and when we come to frame number 4 the frame thickness faces the stern of the vessel.  The reason for this will be explained and shown later on.

Now, as we come towards the stern we have to consider two things as we are drawing the keel these are:-

a)   the position of the motor
b)   coupling
c)   propeller tube

What I normally do is lay the motor or gear box in my case; and the coupling all joined together along with a brass tube the same diameter as my propeller shaft onto the drawing of the keel.  This gives me the chance to move it around and find the best position; I then mark on the keel a rough approximation of the motor mounts and also the stern tube.

I then mark in the thickness of the stern tube on the keel plan.  Eventually this is where we will cut the keel through and insert the tube.

Once we are happy with the notches that we have marked into the keel, we move on and mark the corresponding notches onto the frames that we have drawn.

When we have finished drawing the notches for the keel we draw in our deck edge notches; this is going to accommodate the stringer which is going to run right around the deck edge and give support to the deck and also the side of the hull.

After we have finished that, we have to sit and work out about removing the centre of the frames.  Some frames we will be able to leave solid and some we will have to remove the centres from.  As a side note, if we were going to turn this into a plug mould for fibre glassing, we would not need to remove any of the centres of frames.

As a rough guide, as to how thick to leave the frame wall thickness, you have several things to consider.  The frame must be wide enough not to flex when we put a reasonable amount of pressure on the edge, and, yet it must be thin enough for us to install internal items into the hull such as batteries, speed controllers and so forth.  Also, since this is plank on frame and we will be using brass pins, it must be wide enough so that the brass pin we use does not protrude onto the inside of the frame.

That will give you some guidelines of how thick or how wide to leave the frames.  A lot of it comes from experience.  What I normally do now when I have decided roughly how much of the frame I am going remove, I draw in with pencil first, the area I am going to remove.  Go over the pencil line with ball-point pen and then replace the tracing I made of the frame over the top; and I then trace around the area I have just drawn in.   When I have completed this, I flip the tracing paper over so it is on the opposite side of the frame and then transfer the shape onto the plywood.   This keeps both sides equal and the same.    I do this to the selected frames that require the middle removed and once I have finished this, I double check all of the drawing I have done on the plywood. 

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:51:58 pm
NOW THE EXCITING BIT  :) when we are happy it is now time to cut the frames and keel out.   Every modeller has his preference of the tools used.  There are numerous saws which can be used to cut the frames out, you could use a jig-saw with a fine blade, a scroll saw, a coping saw – but, I prefer to use a Hobby’s Fretsaw – have a look at my photograph included.   There is no great advantage of using a Fretsaw, it is just a tool that I have been brought up with and used all the time.  Mind, one golden rule with any saw LET THE SAW DO THE WORK, DO NOT FORCE THE SAW INTO THE MATERIAL and always cut on the good side of the line.   It is a lot easier to remove material than it is to stick it back on.  ;D

Now then, what I do, when cutting any frames out; normally the material is roughly 4 foot x 1 foot which we have drawn the frames and keel on.   This is a bit awkward when it comes to cutting it out – so I cut it into manageable chunks around the lines – yes make sure that you don’t cut through any you need – yes I have done that before myself.

Once we have cut them into manageable chunks, and then proceed to cut around each frame, leaving about ½ mm on for us to sand off.  When we have finished cutting our frames to size, remember DO NOT CUT OUT ANY NOTCHES AT THIS TIME OR DO NOT CUT THE MIDDLES OUT sand so that you leave a trace of the line you have drawn on the edge.  At this stage, try and keep the edge of the frame nice and square with the face of the frame.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:54:17 pm
When sanding, also, it is time to level off our support legs; again, sand them so you just leave traces of the marking line on.   Stand them up on a flat surface and use a set square to check that the centre line drawn through the frame is at right-angles to the base of the support legs.

Sometimes, you may find you will have to sand more off one leg, than you do off the other to accomplish this, but when you have finished all of this; it is now time to remove the centres out of the frames, with your chosen method of saw.

You may notice that on some of the frames I have cut circular holes towards the bottom edge of the frame.  The reason I do this on the finished model it allows passage of cables, electrical cables, servo wires through the frame rather than going over the top.   Also, it does keep the cables neat inside the hull.

When we have finished removing all the centres and we have sanded them, we can now move onwards to the next stage which is to remove the keel notches.  Some of the notches in the frames towards the stern of this model are very long.  To aid a square cut of the saw, I first use a steel rule and a scalpel to score down at least two layers of the laminate in the ply.  As I say, this helps to keep the saw running straight towards the side of the notch.   I normally do one pair of notches at the time, one on the frame and the corresponding one on the keel.  This way it helps me keep in check that I am cutting them all square and if they are slightly off square I can rectify them with a flat file and some sand paper.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 12:57:07 pm
When I have finished all of the notches, I do a dry run and assemble all of the frames onto the keel.  This is to ensure that they all fit exactly where they are supposed to fit and there are no frames sticking too high up; or, sticking out to one side.  Once we are happy, and on this particular model I am incorporating the motor bed in with the frame assembly, also the rudder servo tray.  I have included a photograph to explain this.

Our next stage of the build then, includes a little bit of ‘hardware’ the propeller shaft.   This I have manufactured from a shop bought prop shafting tube.  The original length of the prop shaft tube was 6 inches and I only required a prop shaft tube 3⅛ inches overall length – to obtain the length required I reduced the overall length using a plumber’s pipe cutting tool.  I then proceeded to remove the inner burr on the piece that I required with a rounded file.   I gently tapped out the bush from the redundant piece of propeller tubing ensuring that I did no damage to the inner centre or the diameter of the bush.  I dropped this bush into the freezer for at least one and a half hours.  Not telling the lady of the house  :o after the bush had been in the freezer for that length of time, I removed it from the freezer next to the gas cooker where I had previously heated up the piece of propeller tubing I was going to use.

Quickly placing the bush into the heated end of the tube with a slight tap, the bush went into position i.e. home, and, it was left and allowed to cool down.   So, that is how I made the short prop tube.

The next stage is to fit it actually into the keel.   The first operation, where I had marked the tube onto the keel, I cut this shaded area out – see photograph also, I made two side cheeks from 6mm ply – now the keel is 6mm thick but, the prop tube is 8mm thick – so, what I did was add on two pieces of 1mm plywood to each side cheek, leaving a gap so that the tube would go through.

The first stage in the operation I glued one cheek piece in the correct position on the keel.  I allowed this to dry; once it had dried I mixed an epoxy resin up; and I pasted this around the propeller tube placing it in position, clamping the other side cheek and the top half of the keel in place – then set it aside to harden thus ensuring that the tube was in line with the keel.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:00:24 pm
Now moving on to another part, which we will have to manufacture, but which is not actually a part of the model, but it does aid the building.   It’s the building board.   In my case it is constructed from ½ inch thick chip board – 34 inches long x 10 inches wide.  Having one good straight side – on the reverse side of the building board I glue and screw two pieces of softwood support timbers down the length of the building board – see picture.

This ensures that the building board doesn’t distort or bend.  The first operation is to mark the centre line in the middle of the building board.  There is a photograph where you will see I have drawn a centre line down the centre of the building board and you will notice that the centre line is drawn on top of masking tape.   This was only done so that the line would show up for the photograph.   Once this line has been drawn; the next stage in the operation is to mark out from the plan the frame spacing on the centre line.  At each frame spacing we draw a line through the centre line at 90º these now become our reference marks.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:03:11 pm
First of all, before we mount the frames, we need to put the securing blocks in.  I just use softwood timber for this, as long as it has two square edges 90º to each other.    I mark the centre line in the centre of the securing blocks on three faces – i.e. top and two sides.

I then clamp a setsquare down the centre line of my frame.  Line the end of the setsquare up with the centre line of my support block; and clamp the frame to the support block, ensuring that the setsquare and the centre lines do not move.

Replace one of the clamps and drill and screw the frame to the support block and once you have secured one side you move on to screw and glue the other leg to the support block.

Now, this is ready to be offered to the building board.  First of all you line the centre line which you have drawn around the support block up with the centre line which is drawn down the length of the building board.  At the same time the front edge of your support block is lined up with the line which is drawn at 90º to the centre line of the building board.   Once you are happy with the set up secure the support block with two screws at either end.  There are photographs to give a good explanation of this.

Once I have one frame set up on the building board and checked that it is square and secured – horizontally and vertically – I move on to the next frame towards the stern.  Set that one up exactly the same, lining it up and then securing it to the building board and move on to one frame towards the bow.  Repeat this process until we have all the frames mounted on to the building board.   When we are happy we then proceed to glue the keel into the central keel notches of the frames.  Allow the glue to dry and ensure that all of our frames are parallel with one another, before the glue dries.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:05:42 pm
When the glue has dried, we move on and put two false stern decks in and two false bow decks in.  This aids the shaping of the deck stringers that run around at deck level on the frames, because, towards the bow and stern there are some tight radius’ and when we come to fit the deck stringers, you will note that the notches in the frame will have to be angled towards the bow and stern.   I did this with the first three frames from the stern and the first three frames from the bow filing an angle on the notches.  We then proceed to add the deck beams; for ease I have laminated these out of two pieces of Obechi 5mm x 2mm.  These were clamped into place and allowed to dry.

The next stage is fairing and sanding. This particular stage in the build is pretty important and critical to the finish of the planking.  What we must do is sand the frames so that they all follow one another without any humps or bumps or frames sticking out too far.  Eventually, the edges of the frames will end up with a taper – either towards the stern or the bow.  The frames edges in the middle section of the hull should remain flat and even.  We do this with a variety of longish pieces of wood – say a length that will at least span 2-3 frames in length with one edge covered with sandpaper.  We should have 2-3 of these, one round piece of timber or tubing to get into the concave shapes; one flat and one piece of timber triangular shaped.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:07:36 pm
AND SOME MORE PICS.....showing planking

 O0
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:09:44 pm
As we have mentioned, it is worth spending a bit of time here – just to ensure that it is right.

We test by placing a piece of planking material over the frames; and looking to see if it sits squarely on all of the edges that it touches.  Also, it touches all of the frames edges when it is bent over them.

There are no frames sticking up or below the piece of planking material.  When we have finished this, give it a good dusting down and prepare to commence with the planking.

There are numerous ways to plank a hull; depending on what the hull is going to be used for.  If we were going to varnish the hull to show the planking we would have to taper the edges of the planking as per a proper boat build (carvel planking).

As we are going to eventually cover the hull with a polyester resin and possibly plating, the way the planking is applied and the material of the planking is not that detrimental to the build and may vary.  Some people prefer to plank in balsa. 

I myself prefer to plank in Obechi, which is a slightly tougher material to work with than balsa.  Sometimes Obechi may require boiling or holding over steam; if you are going to follow tight bends with this type of material.

So, we are going to start planking.

We require some tools for this and some building pins; I have what is called a small fretwork hammer – it’s a very smaller hammer, not much bigger than a ‘toffee hammer’.  This is what I use to drive the pins home with.  You can purchase a proper nailing punch; also, you may require some long-nosed tweezers to hold the pins with; plus, a small jeweller’s drill with some small 0.5 mm drills.  Plus of course, the glue – I use Evostik PVA exterior grade glue.

The first plank I apply is the one which runs parallel and next to the keel.     I start nailing on the centre frames, working out towards the stern first.  As you will see, as it approaches the stern the plank begins to twist vertical.   When it twists vertical we must keep it level with the top of the keel.   

It is policy to clamp the very end of the plank to the keel, rather than nail it.  This is because sometimes with the plank being twisted – it will split when driving a pin-nail through.

Once we have this end of the plank glued and pinned, we move on to do from the centre to the bow in the same way, keeping the plank parallel with the keel.  We come to apply the 2nd plank and we run a bead of glue along the mating edge of the plank that is going to butt against our first plank.  We start again, in the centre, working out towards the bow.  This time though, because of the shape of this particular hull, you will see that this 2nd plank naturally falls away from the 1st plank creating a ‘V’ shaped gap.    If required we could force this gap closed, but, this would create an uneven shaped hull.  We therefore allow the plank to form a ‘V’ shaped gap.

This ‘V’ shaped gap will be filled later on in the build with what is known as a ‘stealer’ plank.   We will describe this later on.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:12:14 pm
Once we have pinned and secured the 2nd plank at the stern, we move on to secure this plank at the bow working from the centre.   This time, you will see that the plank will butt up with the first plank all the way up to the bow.    But where our problem lies is the buff shaped bow, the planks may require steaming – but, in my case they did not.

When we have secured this plank in place – we move on to the 3rd.  Yet again, you will see the 3rd plank creates a ‘V’ gap at the stern.

I carry on, until I have 5 planks on one side of the hull.

Then, I turn the hull around – and I put 5 planks on the opposite side from the keel, using the same methods.

Doing it this way, allows the first set of 5 planks to settle in and the glue to harden.

If we were making a larger hull, we could come back to our 1st planked side and put another 5 planks on.   But, the size of hull and the width of planks I am using which are 10mm planks x 1.5mm thick have covered nearly half the side of the hull.

Now, our next operation and planking is to work from deck edge up towards where we finished planking.   We do not try and follow the rake of the deck; but, we do try and put the plank on as parallel to the keel as possible.    Once we are happy – glue and pin this plank in place.

Then move over to the opposite side of the hull and put that one plank in place at the deck edge.

Once that is done, come back to our 1st plank at the deck edge; glue and pin the 2nd plank next to it.  You will see, yet again, as this plank reaches the stern of the vessel – there is a ‘V’ shaped gap appearing between the 2 planks, but, this is less again.

We carry on planking in this method, from the deck up over until we actually meet our 1st set of planks.   This normally is somewhere in the region in the turn of the bilge area.  This is where we have to cut and shape the planks to fit.

If you have a look at the photographs, you will see how I have done it.   How I took the edge of 1 plank underneath the edge of the last laid plank to get the angle for marking and cutting.

We have closed the gap up now between the 2 sets of planking and we come to the stealer planks.   This is where we have to make a plank up which resembles a wedge or a triangular shape.   Mark off the length of plank required; and, also the width.   Use one straight side of the plank as one side of the wedge/triangle and draw a line from one corner to the opposite corner to create the triangle and then cut.   So you are left with a tapered piece of wood. Dry try fit into the gap first and when you are happy apply glue to both edges and gently tap the wedge into the gap so it’s a neat tight fit and then allow it to dry.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:13:56 pm
When we have finished planking and sometimes the planking may look a bit unprofessional, but do not worry too much – we leave it for 24 hours for all of the glue to set.

We then trim all our excess planking off, at the bow and the stern with either a fine toothed saw or a sharp scalpel blade.  Then just sand it into shape.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:15:18 pm
The next process I do is sanding the hull.   I commence with medium to coarse sand paper wrapped in a square block about 4 inches x 2 inches.

Sand so all the sharp edges, unevenness of the plank edges are removed.

When this is finished, I give it a good dusting down again.   I go back and use P38 filler to fill all gaps, unevenness in the planking etc.  Once this P38 is dry – I go back sanding again.   Remember don’t be half hearted with the sanding – fill all hollows and bumps etc.     When we are near enough coming to finish our sanding, we work back through all grades of sandpaper, working towards the fine grades, but not too fine.   We have to leave a ‘keying’ surface for the resin to key into the hull.   At this stage, stand back and have a good look at the hull to ensure you haven’t missed anything.    Give it a good dusting off – but keep the hull dry!

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:17:55 pm
We move on now to applying our first coating of polyester resin.    I personally just use the stuff you purchase from the Auto-shop which was mixed with hardener to the correct ratio and applied to hull liberally.   Make sure all areas are covered.   Allow this to cure.  Make sure also that you follow all instructions about working areas, ventilation and temperatures & so forth.

Once the first coating of polyester has cured, give it a light sanding with coarse sandpaper NOT TOO HEAVY JUST A LIGHT SAND OVER REMOVE DUST and now we are going to apply the tissue mat.  I apply the mat on this hull in two panels.  If you look closely you will see how I have cut ‘V’s into the matting to allow it to curve around the shape of the hull.   Any matting does not like to be folded onto itself.  So, it’s always best to cut the fold out.

When I have marked up and cut the two panels to size and shape for both sides of the hull, move them to one side – mix up sufficient polyester resin with hardener to coat one side of the hull.

Apply the resin to the hull first and immediately lay the matting over the top of the resin.  Stipple the resin through the matting, checking that you have no air bubbles or creases, you should roughly have about 20-30 minutes working time at normal room temperature between 18-20 degrees – this may vary between the manufacture of the resin and the amount of hardener applied.

When we are happy that there are no trapped air bubbles and we have no creases or folds in the mat, we move on and do exactly the same on the opposite side.

Allow this to dry.  Don’t allow it to cure fully though.

We then add a further two coatings of pure resin on top of the matting; and, set this aside for at least 24 hours to harden properly.

CAUTION NOTE:  Make sure that the Polyester resin you use is not past its shelf life date!  :embarrassed: It takes ages to scrape it off the hull, when the resin doesn’t go off.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:20:27 pm
Once the resin has dried, our next stage is to finish sanding down the hull.   I normally begin with something like 80 grit sandpaper to get rid of all the brush marks & lumps in the resin.   I then work down through the grades until I finish off with wet ‘n dry and all of these sanding operations I always use a piece of sandpaper wrapped around a block of wood – as this prevents any hollows being formed in the wrong places.  Also, make sure that you do not cut through the resin and into the timber.

At this stage, you can decide whether you are going to assimilate the plating on the hull.  I chose not too so my last job, before I remove it from the building board is to check for air pockets trapped behind the resin, and these will show up as little white patches or dots.   The small dots will be filled with paint but the larger ones I dig out and fill with P38 filler and smooth back.   

I have tried to show photographs of the several stages of sanding, but they don't come out too clear in the artificial lighting of the garage  :o
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:22:24 pm
Now the exciting time  :D time to cut the hull off the building board.

If you wish, you could unscrew it, by just undoing the screws that support the frame building blocks, ah but sometimes impatience kicks in as it does with me and I used a junior hacksaw to cut through the frame support legs.

The next stage after this, which I do, is to build a stand for the model to sit into.   Normally, I pick two frames well spaced apart & trace these out onto some half inch thick plywood.

The edges that are going to come into contact with the hull, I glue on foam rubber.   Everyone has their own way and particular style of making a stand for their models - the only thing I can suggest is to ensure that the stand for the model is long enough and wide enough to hold the model secure whilst being worked on.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:24:10 pm
Now to get back to the build of the model and good visual inspection of the inside of it.   One trick is to hold the model up to a very bright light and looking in the inside, the light will shine through thinned areas of planks.  This is where you may have to put in a good re-enforcement of either tissue mat or chopped strand mat on the areas that are very thin.

Also, to smooth out areas where the filler you have used has come into the inside of the hull.   Once we are fairly happy, we can coat the inside of the hull with just pure resin which I have done on this model but, for those who wish, you can put a layer of matting along with resin in.

This again is set aside and allowed to harden.

We then proceed to remove what remains of the support legs off the frames; with a small saw and after we have removed them, we sand the top of the hull to the correct shape.  We use a long piece of wood wrapped in sanding paper to do this.  To get the correct rake on the hull, also the correct camber on the deck, we then finish off sanding into the centre of the hull.  This avoids breaking off or chipping the resin that we have put on the outside of the hull.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:27:38 pm
The next stage then is to add the rudder and propeller support frame.  This I made from ⅛ plywood traced from the plan, leaving the area which comes into contact with the hull oversize.  It was a case of sanding the contact area to the profile of the hull.   This takes time and SHOULD NOT be rushed.   Once you are happy with the fit, it is time to epoxy it into place, ensuring that it is square vertical and also in line with the keel.

The next stage after that is to fit the false exterior keel.  I made this up from two laminations of 2mm x 4mm strips of plasticard.  These were glued and pinned to the hull.

I then sanded and faired the rudder frame into the hull.   

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:31:31 pm
We then move on to the fitting of the rudder and rudder shaft – this rudder post has a set in it.  It is important to remember that the hinges of the rudder must be in line with the top of the rudder shaft.

The first procedure is to actually make the rudder tube.  You could if you wish purchase a commercially made rudder.   But, I myself opted to make my own from 3 sections of tube which all fit into one another as in the photograph.

These are all cut using a plumber’s small pipe cutting tool.  Then clean the bores up with a small round file.   Assemble and solder it as per photograph.

Assembly of the rudder is the next stage – and once this was complete and installed and made sure that it was moving freely, I moved onwards to fit the servo and linkage arms.   I prefer to use what is called a ‘closed loop steering servo linkage’ the reason being is, if you can imagine if you are riding a bicycle only having one hand on the handle bars, how difficult it is to turn a corner – well all the effort is down one arm.  But, when we have both hands on the handle bars at opposite sides as one arm pushes the other arm pulls and therefore sharing the load.   If this is adopted on the model, it balances out the load on the steering servo.

Once I had finished and I was satisfied with the movement of the servo and the rudder, I went on to fit the main motor and gearbox.   This was a simple operation as I had pre-made the gearbox mounting plate and also pre-cut the location holes for it and the frames.   The simple method of screwing the motor to the base plate and fitting it into the hull along with the appropriate coupling to the propeller shaft.  At this stage, I connected up the motor to an amp-meter and the battery.  I disconnected the coupling to the propeller shaft and ran the motor, checking the amperage.  I then reconnected the coupling to the prop shaft and re-ran the motor, comparing the amperage readings.   Thus ensuring that there was no increase in the amperage – there was but only 0.2 of an amp which is quite acceptable.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:34:49 pm
When we were finished and happy with that and ran the motor for about half an hour to bed everything in – I turned the hull over and proceeded to fit the bilge keels.   I do this using a flexible measuring stick, in other words an old piece of plastistrutt which bends around the hull easily and transferring the position of the bilge keels from the plan onto the hull.   

The bilge keels were then made out of 4 mm x 1½ mm plasticard and I super-glued these into position on the hull.  When the glue had dried, I proceeded to drill through the centre of the bilge keels.  I drilled through the hull so I could insert stretch copper wire, and this in turn was glued into place in the inside of the hull.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:36:14 pm
The next stage after this is to ensure that the rudder servo works correctly and you are happy with it.   The motor runs correctly and you are happy with that.  As soon as you are entirely happy that everything inside the hull is working correctly, progress onwards to fitting the deck.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:38:49 pm
This is where you have to be on good terms with the lady of the house.  I made the deck from 2mm lite ply for this model and the procedure was to place the sheet of lite ply on the bed and then turn the hull upside down on top of the lite ply and press down hard, so that the ply bends into shape of the deck of the hull.  Draw around the outside of the hull onto the ply (not onto the bed).  :)  We then proceed to cut this out, leaving 3-4 mm plus on the line we have drawn.

The next stage is to set the hull square on the building stand and then apply glue to the tops of all of the frames and the deck edge.   Then apply a couple of bits of cellotape to ensure that the deck is pulled around the edges and then apply weights onto the top of the deck – as you can see in the photograph.    Set this aside to fully dry.

Once the deck is fully dried and the weights have been removed :) the next stage is to sand the excess material off the deck.   So that the deck is now flush with the sides of the hull and to the correct shape.   For the deck material I used 2mm lite ply as this bends a lot easier than 1/16 ply as the hull has a fair rake from bow to stern and also a good camber across the deck.   The lite ply formed to this shapes easier.   
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:45:21 pm
The next stage in the construction should be to mark a centre line all the way down the deck, from bow to stern.

This is where we refer to the plan and now we need to mark a reference point on the centre line to take all measurements from for superstructures and items on the deck.   I normally use either the aft end of the main superstructure as the location point or the forward end of the superstructure.  In this case I used the forward end of the main superstructure as my main reference point.   I obtained the overall length of the main superstructure plus engine casing and marked this length and width out onto the deck, using measurements from the plan.  Then, I decided what area needs to be opened up to gain access into the inside of the hull and in this case it could be all of the marked out area.    So, I redrew a line ⅛” inboard around the line I had drawn which represents the extreme exterior of the superstructure.  You may remove this area at this time, but I opted to leave it until a later date to remove.   

The next stage in the build is to mark out the bulwark supports and to apply the bulwarks.  The bulwarks are going to be made out of 1/16 ply and the support pins are going to be made out of 1/16 brass or copper rod.

First of all, we draw a line parallel around the outside of the deck edge 1/32 of an inch inboard of the deck edge. 1/32 is 1/16 thickness of plywood for bulwark and ½ the diameter of the pin which in our case 1/16 pin = 1/32.   We then start at the bow; using our plan as a reference, mark the spacing of the bulwark upright supports onto the deck edge on the line we have drawn, both sides of the hull.   Then, we must make a jig up out of small piece of scrap ply; this jig will give us the overall height of the bulwark pins which must be at least level with the height of the bulwark or 1/16 below the height of the bulwark, also the angle of the bulwark pins.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:47:38 pm
The next stage then, is to drill /16 holes through the deck to accommodate the pins.   We ensure that we DO NOT drill through the side of the hull TIME AND PATIENCE MUST BE USED HERE.   I do one pin at a time, drilling and gluing into position and then bending to the correct angle, working all my way from the bow to the stern on one side and then do the opposite side afterwards.   Once we have fitted all the pins and glued them in and double checked our angle and the heights, we move onwards to the next stage which is actually the manufacture of the bulwarks.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:51:36 pm
On this particular hull the most difficult part to produce is the stern piece, for this I made up a template from cardboard.   The cardboard I had was from the inside of a new shirt packet – but an old cornflakes/cereal box cardboard would do.   

I bent this around the stern so it became into contact with all of the pins around the stern, as can be seen by the photograph.    I temporarily cellotaped this into place, and, with a pencil I marked onto the cardboard around the deck edge, giving me the perfect profile (or near enough the perfect profile of the deck where the cardboard comes into contact).

I then cut the line out on the cardboard and tried it against the hull to ensure that it fitted correctly.  The next stage was, on the cardboard template, to mark off the bulwark overall height, plus at least ⅛ of an inch.

This new line you are drawing runs parallel with the line that you have cut, at the deck edge.   Now you have cut this piece template out and retry it out against the bulwark pins on the model at the stern.   Satisfied that there are minimum gaps and it sits nice and neatly transfer this cardboard template shape onto a piece of 1/16 ply.

Now when we transfer this onto the plywood, ensure that the grain of the plywood runs vertical – in other words the grain runs up the height of the bulwark.  This facilitates for easy bending.   I cut this shape out of the 1/16 ply and soaked it in boiling water for at least 20 minutes.    I then clamped it to the bulwark pins at the rear of the model in position.  This was allowed to dry out in place.

With superglue, I then glued the stern bulwark section to the pins and the deck and allowed it to dry thoroughly.   The next stage is to do the side portions and the bow section.   First of all I clamped a length of 1/16 ply to the outside of hull so that at least the height of the bulwark plus ⅛ was above deck level.   I then drew around the inside marking the deck edge and shape onto the inside of the plywood.   Cut this out – and glue it to the pins and deck of the side of the hull.    I followed this procedure through until I had completed both sides of the hull up to the bow.   Then I allowed it to dry.

The next stage, I made a little height gauge up so that I could mark off on the inside the bulwarks the overall height.  I proceeded to mark a line all around the insides of the bulwarks at the correct height.    I then carefully sanded with a variety of sanding blocks and sandpaper to achieve the correct height of the bulwarks.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:53:21 pm
.... more pics of the assembly of the bulwark  ;D
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:55:44 pm
I proceeded to mark off the water freeing ports in the side of the bulwarks.   On this model I am going to have them slightly open to allow for drainage for water from the deck – so you will see I have cut them all out.  I used a brand new scalpel blade and a steel rule, cutting one freeing port at a time.   A tip here: If like mine, you have a joint right next to where you are going to cut a freeing port, clamp a piece of wood behind the joint so you are not putting any undue stress on the joint whilst you are cutting through.

When I had finished cutting all the freeing ports out and sanded and cleaned them up, this is the stage that I removed the centre section of the deck, thus allowing me access to the inside of the  hull.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 01:58:20 pm
Once I had cut out the area I wanted to be removed to gain access into the hull, I needed to put a combing around it.

First of all, I glued underneath the deck ¼ inch square softwood, level with the edge opening of the deck all the way around the opening.

The height of the combing depends on the personal choice and where the model is going to be sailed.  If you are going to sail it in the lakes of Wales, I would recommend the combing to be at least 1 inch above deck level – because remember this is the only thing which will stop the water entering the hull.

In my particular case the combing is the average of about ½ inch high.  This was made out of 1/16 ply – glued to the inside and the face of the ¼ inch support pieces I had glued underneath the deck.   The corners of the combings were supported with Obechi timber just to add strength.   

Now, it’s just a case of going over the hull – light standing and filling in bits and pieces and basically we have now finished the hull!  {-)

The next stage is obviously superstructure and fittings.   

I wish to do this at a separate topic to follow on from this one.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 28, 2007, 02:00:27 pm
As a footnote – there are several unanswered points  :)

I have never mentioned ballasting the model or calculating its weight.  This is my personal preference – to do this at the end – or at this stage now, where I can put it in the test tank (the bath  :) ) with no fittings or superstructure to be knocked off or damaged and I can play around with a variety of weights until I get it right.

The second thing is when to fit the motor and also steering servo.   There are several schools of thought on this subject, all schools are correct in their own way.   Some people prefer to completely finish the model and then fit the running gear, as we will call it, being if it has to come out – you can get it out quite easily and refit it – in the space that they have provided.

Whereas I like to fit the motor and running gear whilst doing the build when the hull has no deck on it, and the reason for this, is, I have plenty of room to work around inside the hull with no fear of damaging any fittings and so forth, when things go wrong. (That blinking motor doesn’t fit)  :)

I hope you have enjoyed, and understand what I have been trying to explain.   

Aye
John E
Bluebird.


 


Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on December 30, 2007, 08:34:00 pm
Hi there one and all, a quick sneek preview of the progress of the superstructure build - more to follow - do you think the funnel looks a bit 'odd' - its off the drawing, but looks odd to me.  Right to the drawing as I say.

aye
john e
bluebird
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:23:45 pm
SUPERSTRUCTURE BUILD FOR THE TUG CERVIA

A little pause for thought first; at this stage, we have several options open to us and the options are purely a personal choice.   Where do we take our build from here – some modellers prefer to build a model as near as perfect as one can get; some modellers like myself on certain plans like to build the model as depicted on the plan, and, some modellers like to build a ‘stand off’ version.

We will look at the choices on merit; let then take the first one:

•   We want to build a model as close as we can to the ‘prototype vessel’ as possible.   In this case we have to put our Sherlock Holmes’ cap on – we have to do a lot of investigation and research on the vessel’s history, design, alterations throughout its life, because a vessel is not known as a ‘she’ for nothing.   Like a typical woman; she changes her clothes and appearance on a regular basis.  ;D   

We have to decide at what period of time we are going to represent our model; and, having picked a particular time, we have to amass as much information about that vessel with regard to its fittings, structural alterations and so forth – this enables us to build a good representation of that particular vessel.   This can not only be very time consuming, but also very costly.    The plans we are using for the tug Cervia, no doubt, fairly accurate – I have noticed one or two discrepancies when looking at photographs of her.   To give you an example – on the back end of the engine room top deck casing – on the photographs I have – show a rear door access point to the engine room.  Now then, on the plans this is not shown.    On the plan it shows radar – now the time she had radar fitted the doors were fitted to the engine room casing.   This could have been an oversight by the draughtsman; however, it just highlights one small problem we have to overcome when trying to build a replica of a particular vessel.

Although building a model to exact scale can be very rewarding, in more ways than one.   It can be also be very stressful.    The last point really is if we had decided to build an exact replica, we would have decided this at the very beginning of the build so we would not then come across problems:

•   To build straight from a plan - I prefer this option at times.  To build like this can give you some leeway when you have not got the correct information for particular parts of the build, e.g. full information on steam windlasses and so forth.   You can build off the plan what you see and it should give a reasonable representation of the item or, if you wish, you can purchase a fitting which is near enough what has been drawn on the plan.   We also can afford to be a little bit lenient on the quality of our build – this is because every modeller suffers the same – some good days when everything goes right and looks well and some days when everything goes terribly wrong.   ::)

•   To build a stand-off model – there is nothing wrong with this type of build – IT PLEASES THE BUILDER if he doesn’t like the particular bridge which is on the plan, he can make his own up.    If one wants to put something on the tug/vessel that was never there on the original one can.

AT THE END OF THE DAY the real answer to all questions has to be the enjoyment we gain from building the model, and, the enjoyment we gain from sailing it.   
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:27:00 pm
If we move on and look into the superstructure build of the Cervia, or indeed any superstructure build for any vessel; on close inspection we will see that superstructures are built up of oblong/rectangular/square shaped boxes, half round shapes, circular shapes.   The majority of superstructures tend to build up of box shapes.

Okay, so enough of my waffling!

Let us take a look back at the plan of the Cervia.  We can break the superstructure down into three basic parts. 

Here is a little tip: When studying plans of any vessel, sometimes those lines can become very confusing and you find it difficult to follow a particular line.  So what I do is lay a couple of sheets of plain A4 paper, to cover sections of the plan. This obscures those lines which are distracting me and then, I can focus on the area I am working on from the Plan.

1.   The main superstructure at deck level an oblong box with a rounded front end; behind the main superstructure it steps down towards where the tow hook is and either side of that there are coaling hatches.   That is another small rectangular box and behind that going aft, there is the engine room casing (skylight casing) - another rectangular box, only this time it has a curved roof.   On top of the main superstructure, we have the bridge – that is another square box structure but, this time it has a front end which is made up like three sides of a hexagon.   This forms the bridge front.    Behind the bridge, we have the funnel which is an oval shape; then masts and on top of the bridge we have a ‘flying bridge’ which is basically an open box.  So, all we are constructing then are basically five boxes. 

So we will make a start; in the photograph you will see I have traced from the plan the side profile of the main superstructure and transferred this to 1/32 ply.  I then cut two sides out, port and starboard.   On this particular plan there are no front or back elevations. 

I had to take the width of the superstructure from the deck profile plan.  Also, I had to take the height from the side profile.  This gave me two dimensions to calculate the size for the rear of the superstructure.     

I also traced off the deck profile, the radius’ of the front of the superstructure and this in turn was transferred to 1/16 ply – these became formers for me to bend 1/64 ply around to create the front radius on the main superstructure.  This is all shown on photograph 1.    The last thing I did was trace out what we will call ‘the boat deck’ – this is the roof of the main superstructure that the lifeboat, funnel and bridge are mounted on.

The first stage of the build was take some
6 x 1.5 mm Obechi and glue it along the bottom edge of the side that is going to become the main superstructure.

I did the same with the front edge of the superstructure; I then repeated this operation on the opposite side.   I then took the back section of the superstructure and glued onto that 5mm square balsa wood on the inside edge.   I did the same on the front bulkhead.  I assembled all four pieces together and this created an oblong box – without a roof.   
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:31:21 pm
The next stage in the build was to glue the two semi-circular formers which I had cut out of 1/16 ply and glue them on the front of the superstructure – gluing in 5mm square balsa wood in the corners.  This supports the joints.

I then wrapped a piece of 1/64 plywood around the formers and glued it to either side of the superstructure.   I allowed this to dry.

Once it was dry I sanded and trimmed the 1/64 ply to the correct height and blended it in to the sides of the superstructure with the aid of P38 filler.   Once I had completed this, I moved on to glue the boat deck (roof) onto the main superstructure.

When this had all dried; it was placed onto the model and a line was scribed all the way around where the superstructure meets the deck.  This gave me the deck profile to which I was to sand the bottom of the superstructure so that it fitted snugly to the deck.

Once I had finished this, I moved on to make the smaller rectangular box which is where the coaling hatches and tow hook are; this structure was made in a similar manner to the main structure.

The third part of the main structure, the engine room top deck casing or skylight was made in much the same manner.   This time though the roof is curved.  This again was made from a basic box section shape.  This time though, the ends of the box section shape had a radiused top section, which in turn produced a curved roof.   All of these structures are made from 1/32 ply.   

When we have finished gluing and the glue has dried I give the main superstructure two coats of sand ‘n sealer inside and out.   Then we give it a light sanding to finish off.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:33:38 pm
We move on now to construct the wheelhouse. This sits on top of the main superstructure.  Although on the plan there is no front elevation to show sizes of windows or quantity of windows in the wheelhouse; there is a plan view, of the wheelhouse showing location of the windows in the bridge.

So, using the profile plan of the wheelhouse, along with the plan view, I was able to work out the size and number of windows.  :)  Plus, I was also able to obtain two or three photographs on the web & one from a friend, these photographs show the wheelhouse and windows.

So, all the items required to make up the wheelhouse were drawn out onto 1/32 plywood.   The first items I cut out were the windows and doors.  When I was satisfied that all the windows and doors were square I cut the main shape of the wheelhouse out of the plywood.   The reason I cut the windows out first, was to prevent splitting.  This is because on certain windows – they are very close to the edge of the door and corners of the wheelhouse.

As you can see from the photographs, I began at the aft-end of the wheelhouse, gluing and erecting the vertical sides and moving onwards to the front.   When I had finished this – this again was coated with two coats of sand ‘n sealer inside and out – and then set aside.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:36:20 pm
The next item I made was the ‘thing the smoke comes out of’ you know what I mean the ‘chuff chuff’ aye the chimney pot ……erm THE FUNNEL.   {-)

There are lots of ways to construct funnels – we can make them from solid balsa, plastic tubing (if you have the right shape and diameter).  This particular funnel is oval shaped and I decided to fabricate it out of plywood. 

So, I needed to trace from the side profile plan:-

•   The overall height and width of the funnel
•   The angle it sits on the deck at

I needed to get the oval shape from the deck profile plan.

The procedure I used was as follows:-

I traced the overall height and width of the funnel profile onto 1/16 ply and I cut this out.

I then traced three ovals – two onto 1/16 ply and one onto 1/32 ply.   These were then cut out.

The 1/32 oval had the inner section removed to make facilitate the opening of the inner funnel (smaller oval).

One of the ovals that was cut from the 1/16 ply was cut into half; these then are the pieces so far and now for the assembly:

The solid 1/16 oval was glued centrally to the vertical funnel profile which is in 1/16.  The 1/16 oval that had been split into half/two was glued ¾ of the way up the height of the funnel – one either side.  The one oval with the hole in the centre which was made from 1/32 ply was glued on the top.

At the leading edge of the funnel there were four strips of ¼ square balsa wood glued, two either side of the vertical profile.  This was repeated on the back end of the funnel.

These were then sanded to the same radiuses as the funnel.  This then was wrapped and glued in 1/64 plywood.  All of this was taped up with masking tape to hold the plywood tightly onto the former and set aside to dry.   Once it had dried; we sanded and blended in the joint where the 1/64 plywood had lapped over and also we sanded the funnel to height both top and bottom.   I then added two copper rings – one at the extreme top of the funnel and one ¼ of the way down.  These were soldered and glued on.

This was set aside – and we went back to the main superstructure.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:37:49 pm
..... and - of the assembly of the funnel - it has been dressed off and we have coated it with sand'n sealer  O0
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:39:49 pm
We marked out the location (FOR THE PORTHOLES YA NAR – OR ROOND WINDAZ) alright then port lights  ;) wye aye man.

These were then pilot drilled using a 2mm drill.  Then, rather than using a drill for the correct size of port light – I opted to use a rounded file.   I actually use three files – a very small jeweller’s round file to start with, then open it up again gradually using a ¼” rounded file.    Eventually opening it up with a 3/8” rounded file and I don’t force the file through the hole – as in back and forward motion – I rotate the file as you would do with a drill.   The reason I use a file rather than a drill on fine ply wood is:

a)   If anyone has ever tried to drill thin plywood or thin material without clamping it, or drilling through a thicker material to support it first – you will find you don’t get a true round hole – it turns out more like the shape of a 50 pence piece.   

b)   Also, when you try and drill ply wood you tend to split the first veneer and the back veneers as the drill breaks through – you will find that by using a small file (although taking longer) you will achieve a far neater hole in the ply wood with very little splitting of the veneers.

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:41:36 pm
The next stage was to make the port light inserts – these contain the glass.  The rims were made from brass tubing cut into approximately 4mm lengths the faces were filed flat and the burs were removed.   

I then rolled a piece of ‘plasticine’ out onto a piece of wood – like a flat pancake shape.   I made sure that the face of it was smooth with no marks at all.   I then gently pressed the brass inserts into the plasticine at about 1mm depth keeping the edge of the brass ring level and I mixed some clear epoxy resin and filled all of the brass inserts up with the mixed epoxy – I set these aside and allowed them to set.

When the epoxy had set, I removed the brass rings from the plasticine.   The epoxy is slightly recessed about 1mm back from the brass ring.  This gives a recessed glass effect for a port light.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:45:55 pm
Whilst I was waiting for the epoxy to set in the port light glasses I moved on to the next task which was to go back to the hull.

I cut the holes for the anchor hawsers.  I first took the measurements from the plan for both the location and the sizes of the hawser pipe, where it comes out of the hull at the side.   I made a paper template up, to correspond with these; and like every builder – I forgot to take a photograph  -  but basically it was just a cardboard template with a cross marked on it – that sat against underneath the deck rubbing strake on the outside of the hull and came flush with the bow.  I drilled a small pilot hole where the cross was on the cardboard template - into the hull and moved the template onto the opposite side of the hull and repeated this process.  I was then left with two pilot holes marked on the outside of the hull  (one either side).

I took measurements then from the deck plan, for the deck location of the hawsers.  I marked these off accordingly on the deck of the model and drilled two pilot holes in the appropriate place.    I then reverted back to my needle file, passed the needle file through one of the pilot holes on the deck, rotating the file, opening up the hole until it met with the corresponding hole in the side of the hull.   Once I had opened the holes up to the width of the needle files; by gently rotating the file like a drill; I moved on up to a larger sized file.   I repeated the same operations once again.    One of the photographs you will see I use a tap wrench handle to aid me in turning the file through the hole.   The hole then was opened up to take a length of 8 mm (outside diameter) brass tube.   This brass tube was then passed through the two holes and then epoxied into place.

When the epoxy had set, I dressed the brass tube off, flush with the outside of the hull and flush with the deck with the aid of a Minicraft Drill and a sanding disc.   I repeated the operation yet again for the opposite side of the hull; leaving me with two hawser pipes.    The next stage in the hawser pipe assembly was to make the outside oval ring, which protects the plating.   This was manufactured from copper wire; round nosed pliers, and side cutters.   When I had finished the oval protection ring, it was tried against the plan for size and located and glued onto the side of the hull.   I made two – one for portside and one for starboard side.   

I moved on and made the hawser bonnet; this fits onto the deck.   It was made from copper wire and plasticard. You can see this in the photograph.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 03, 2008, 07:50:21 pm
The next stage was to camouflage the brass support pins around the bulwarks.  This is done by cutting strips of plasticard 3mm wide by 1mm thick.   These strips are now cut to the height of the bulwark and then glued over the top of the brass pin.   They now therefore represent the uprights that support the bulwarks on a ‘life size’ ship.

As you can see from now, a lot of the main superstructure work has now been completed; what happens now is everything we make is either a fitting that we add to the hull or the superstructure.   

I propose therefore to finish this topic off by posting posts of the build as I move on making the fittings, rather than putting it in a one-block form.

Lot easier for me  :)  and a lot easier for one and all to read and respond  :D

Aye
John e
Bluebird



Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 05, 2008, 02:21:48 pm
CERVIA FIXTURES AND FITTINGS

A new day; fresh start; fresh problems to solve  ::)

A lot of fixtures and fittings can be bought off the shelf and there is nothing wrong with purchasing fixtures and fittings for model boats.

Some, though, we may wish to make ourselves; this is entirely up to the person and is your own choice.   I like to make my own fittings sometimes, but, occasionally I do buy some.

For the Cervia, we are going to try and make as many fittings as possible and where I am commencing is going back to the Freeing ports in the bulwarks.   
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 05, 2008, 02:25:52 pm
The first fitting I am going to start with are the storm bars across the freeing ports.  Although these are not shown on the drawing, they will be there on the ‘life sized tug’.  They are a safety device fitted to the real ships, and these prevent items and people being washed overboard through the openings of the storm ports.   On some vessels these are quite large, in fact large enough for a man to be washed through in heavy weather – and that is why there are storm bars.     They are quite easily made and are just lengths of stretched ‘bell-wire’ across the openings, glued into place.   When I had completed installing these across all of the wash port openings, I gave the inside and the deck a coat of primer paint.   
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 05, 2008, 02:30:07 pm
Whilst the paint was drying I moved on to the next item; the eyelets which are located just above the engine room port lights.  These again are made out of slightly thicker copper wire which have been wrapped around a brass tube as a former, to form a spring.   The copper spring was then cut to produce circles of copper wire.  These circles were then slightly flattened in a vice across the width of the copper wire to produce a flat circle. These were then cut into half;  so, one circle made two eyelets.

The next procedure was to make a small jig up from two pieces of brass tube.  One brass tube fits snuggly into the port light hole in the engine room casing, where the eyelets are going to be fitted, and, the other tube slides over the top of the first tube and sits on the outside of the engine room casing.

The segment of eyelet is then placed against the engine room casing, see photograph – it’s then glued into place with superglue.  The jig is then removed and you will see that the eyelet is set at the correct gap from the port light hole. When dry and the excess superglue (which can’t be helped) is then sanded off ALONG WITH FINGERPRINTS  ;D I then gave them an undercoating of paint. 

Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 05, 2008, 02:35:02 pm
Whilst the engine room superstructure was drying, I moved back to the freeing ports on the bulwarks on the main hull.   I had decided to make these a ‘fixed’ item, but to fix them slightly open, to allow drainage of water from the main decks.

The doors themselves are made from Plasticard which are cut and shaped to fit into the freeing port opening; I then placed a packing piece of timber of about 3mm square behind the bottom edge of the freeing port door, wedging it open.  I then applied superglue to the top edge, locating it to the bulwarks.   

After I had finished inserting all the freeing port doors around the hull, I moved on to make ‘false’ hinges.  These again were made from plasticard, only this time I used a strip 2mm wide x 0.5mm thick.  This was then glued onto the freeing port door and on to the bulwark side onto the correct position.   To actually assimilate the hinge piece; I cut short lengths of stretched bell wire AGAIN and glued this into the appropriate position to assimilate the hinge knuckle.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 05, 2008, 02:43:59 pm
What I have forgotten to mention and I will put it in here – one of the jobs I did previous to installing the storm bars – was to cut and fit the edge capping that goes around the top of the bulwarks.   There are two sections to this; a piece of plasticard 3mm wide x 0.5mm thick which runs around the outside edge at the top of the bulwark, this represents the plate stiffening; and the actually capping itself which was made from 0.5mm thick x 4mm wide plasticard and this was glued on the actual top of the bulwark.  I used plasticard here, because it can be bend and moulded with the aid of your fingers and some hot water, to form the tight radius’ which are at the stern of the vessel & the bow with ease.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 08, 2008, 07:55:39 pm

I moved on to tackle the next job which was planking of the fore and aft decks; there were one or two problems which I had to overcome.  A new method I wished to try.  The problem being that I already fitted the bulwarks around the outer edge of the decks and this made fitting the planking rather tricky and awkward, but, not impossible to do.  However, I wanted an easier method.  My solution is first of all trace the area of the deck planking onto a piece of 1/64 plywood – very thin and very flexible.   You could use 0.5mm plasticard for this instead of the 1/64 ply if you wish.  When I had transferred the area covered by the planking onto the plywood; I then cut it out; which gave me a template.   I stuck this template onto a thicker piece of ply wood (half inch in my case) with some double sided carpet tape.  This double sided tape, I found releases pretty easily. 

I then marked out and cut to length - the edge planking.  This is the planking which runs around the outside of the rest of the planks on the model.   If you note, in one photograph, I have glued on one piece of edge planking of the bow planking section - next to it you will see I have pre-bent and clamped the next piece of edge planking to the thick piece of plywood, to hold it in shape, whilst it cools down and dries out.

Once you have finished the edge planking; the next stage is to commence laying the planks.   Start with the centre plank; this is sometimes called the ‘King plank’.  Glue this one in place first; and, then commence laying one plank each side of this alternatively. 

This is where I had a debate, and, it’s entirely up to oneself when doing planking.  I wanted to try the method of using black electricians tape to assimilate caulking on the edge of the plank.   This required me to assemble six planks on their edges and apply a length of electricians tape over the edges along their length.   

When the electricians tape had stuck to the edges of the planking, I then proceeded to cut one plank off at a time, leaving the plank with one edge with a piece of electricians tape down one edge.   To be quite honest, for the amount of planks I had to put on, and, the work required getting the electricians tape to stick on the edge of the planks; it was for me more trouble than it was worth.   I ended up using a permanent black marker – marking the edge of the plank with that.

Once I had finished all of the planking; I used a piece of medium sand-paper glued to a flat piece of plywood – 4 x 6 x ½ inch thick and sanded the planking level.  After this, I sanded again with finer sand paper; and, when I was happy with the finish I removed the planking and the 1/16 ply base which the planks were glued to from the double sided tape that was securing it to the thick plywood.

I then positioned this on the fore deck; glued it in place.   I found that it bent quite easily with the camber of the deck, without the planks opening up which was my fear.   I proceeded to do the stern planking with exactly the same method and when both decks were in position and glued down, I applied one coat of matt varnish.  These decks will later be covered with a satin varnish.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 08, 2008, 07:58:04 pm
and more pictures ......
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 08, 2008, 07:59:39 pm
and the final picture shows the planking at the bow fitted
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 12, 2008, 09:37:31 pm
I have included a couple of scribbles because the camera I use isn’t very good for ‘close-up’ shots – I know I know a bad craftsman always blames his tools.

If we look at scribble number 1, this is how I made up the valve cover hatches.  These sit, front and back of the funnel.   Basically, I started off with a piece of 2mm thickness lite ply; 1mm smaller than the dimensions on the plan.   I clad the edges with 1mm plasticard glued on with superglue, and, then the lid of valve hatch is made up of 1.5 mm thickness plasticard.

I assimilate the hinges with 2mm wide x 1mm thick plasticard strip.  At the end of the hinge, on the opening side, I glue 2 short lengths 4mm long of thin copper wire.

I made 2 of these hatches as above.

Next move on to the ship’s binnacle, which is on the flying bridge; It is made up from pieces cut from an old ‘biro’ pen, various size dowel, a bit of cocktail stick and 2 beads and some plasticard strip.  I think the drawing is pretty much self-explanatory; where I cut the pieces of biro pen apart and where I used these pieces and I feel it makes for quite an effective pinnacle.   The most difficult part to be honest was to stop playing with it and knocking pieces off whilst the glue was setting. 

I moved on to make the engine room telegraph and this again was made from 2 pieces of doweling, a steel washer and a length of bell copper wire which had the insulation removed.    The hardest part here was actually making the handle – follow the steps I have drawn – this shows the shape of the copper wire and the sequence in which I bent it in.  This again was painted and set aside.   

I then went on and made 7 bulkhead doors for around the superstructure.  I commenced using 0.5 mm thick plasticard, this assimilates the flange which runs around the outside of the door and holds the door seal – it is roughly 1mm larger in height and in width than the actual door.   The door was cut from 1mm plasticard and glued onto the 0.5 mm plasticard in a central position – so, you had a 1mm overlap all the way round.

The hinges I manufactured in the same manner as I did for the hatches, from plasticard strip and also copper wire.    I also made the handles from the same copper wire which were then glued onto the doors (they don’t open, they are all glued shut).
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 12, 2008, 09:40:36 pm

The ship’s wheel was my next job.    The ship’s wheels I make from 1/64 ply and 1/32 ply, and, a piece of small diameter dowel for the hub of the wheel and copper wire yet again, for the spokes and handles.   The sequence I construct a wheel is as follows – I cut the outside diameter section of the wheel first, which is a circle from 1/32 plywood of the diameter you require. 

On one face I mark the position of the spokes around the circumference of this circle.   I then remove the centre of this circle and move on to cut two further circles from the 1/64 ply – (these two 1/64 circles are 0.5mm smaller diameter than the 1/32 circle).   The inside hole of the 1/64 circle is exactly the same size as that of the 1/32 circle.
 
I then glue one piece of 1/64 circle onto one side of the 1/32 circle – centrally.    I then glue the other piece of 1/64 circle to the other side – thus sandwiching the 1/32 ply circle in between them.   

I move on to construct the hub.   I cut the length of the dowel slightly longer than the thickness of the ship’s wheel. My first operation is to drill two holes – one dead centre through the middle of the dowel; and one through the side of the dowel from 9 to 3 (on a clock’s face) i.e. straight across.  :)

Now, on the ship’s wheel itself; I drill a corresponding hole – this goes through the edge from 9 – 3 or straight across again  :) as above.

Next operation is to place the hub in the centre of your ship’s wheel, in order that all the holes on the sides of the hub and the wheel line up.  Then, you pass copper wire through all of the holes – holding the hub in the centre.  With superglue you glue the hub in place on the copper wire and also glue the copper wire in place on the outer wheel – ensuring that the hub is central to the ship’s wheel and the hub is flat.

Once the glue has dried; you drill at 12 o’clock through the side of the ship’s wheel in the centre; into the hub but not all the way through.  Be careful not to bend or push the hub whilst drilling into it.   Once you have done this you place another length of copper wire through the hole into the hole that you have drilled into the hub, glue in place and allow it to dry.

Then drill the opposite side – so if you have drilled your hole at 12 o’clock the next hole will be drilled at 6 o’clock.  Once you have done this, you should have four spokes in your wheel.   I normally have eight spokes in the steering wheel; and once they are glued into place – allow them to dry for a good few hours – then trim away the copper wire so that they are all even.  If you wish and I have done this in the past – is put a drop of superglue on the end of the wire and hang it until the superglue dries – this forms like a ‘pear shape’ on the end of the copper wire and it does look like the real handles on the ship’s wheel – but take heed here it does take a long time for the glue to harden.  :)

I have attached a couple of photographs of the ‘flying bridge’ and before our Dicky says anything about me painting – that white band is masking tape – whilst I paint the red band around funnel.
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 12, 2008, 09:44:15 pm
Just going to include a couple of pictures of how the tug and flying bridge are at this moment.

I'm in the process of painting.

The one thing I forgot to mention and add a drawing too - is, I made a 'voice pipe' up for the bridge as well.  This is an easy, simple way, its a piece of 15 amp copper wire straightened and a blob of solder on the end.   The solder is filed to the correct 'pear shape' and a flat face added to it.  It is then bent to the correct angle - you can see it next to the engine room telegraph on the picture.

Aye
john e
bluebird
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 15, 2008, 08:55:33 pm
     
The Electrical side of things  :D
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Before we go too far down the road, building fittings and attaching them to the model, we have to pause for thought for a minute.   

Although we have the motor and gearbox installed and we have a rough idea of what size battery we are going to put into our model; we need now, to look in depth at the type of speed controller we are going to fit, where we are going to fit the TX receiver for the radio and are we going to fit any working functions in the model such as lights, water pumps etc.

The main thing on our list at the moment is:

What size speed controller to do we need?  When we say what size? What we mean is – how many amps do we need and how many volts?

Now the motor I have installed into this model is a 550 motor.  When we tested it ‘free running’ coupled to nothing, the motor was sitting on the bench and we ran it at 6 volt.  According to the book we have and the information sheet, for this particular motor, at 6 volt; she should draw between 0.4 and 0.5 of an amp and she should rotate in the region of between 15000 and 16000 rpm.

This motor is going to drive through a 2-1 ratio belt drive gear box.  So, we will say, she is turning at 15000 rpm connected to the gearbox at the output end of the gearbox, she should be turning or will be turning in the region of 7500 rpm.   At the end of the output shaft, we are going to connect to the propeller shaft, via a Dyco coupling unit; and then onto the propeller shaft and on the end of the propeller shaft; we have the propeller  :) in my case it’s a 50 mm three blade brass prop.  Now, with all of this connected up; sitting on the bench in the tug; the first stage is to connect the electric motor up directly to a 6 volt battery and let it run for at least an hour (aye you have to sweet-talk/make the Mrs a cuppa  O0 ) as it can be on the aggravating side for those who don’t know what is going on  :)   What is actually happening is – we are RUNNING THE MOTOR IN and the PROPELLER SHAFT and we are constantly checking for ‘hot-spots’ – is the end of prop shaft running hot WATCH YOUR FINGERS!!!! IT DOES HURT!!!!   :'( When we have ran the motor for about an hour with no load on; disconnect one lead off the battery – preferably the positive lead.  In between the wire from your motor and the battery; connect an amp meter up.   Make sure the amp meter can handle at least 10-20 amps.

Now once we have connected the amp meter between the motor and the battery; check the reading on the amp meter.

When the motor was free running on the bench, we knew that it was drawing no more than 0.5 of an amp.  So, in theory, with the coupling and propeller shaft and propeller all connected up to the motor through the gearbox; it should be no more than ¾ of an amp to 1 amp.  If this reading is higher; we have some friction somewhere and something must be preventing the propeller shaft from turning freely.

If we have a hotspot or we are pulling in the region of more than 1 amp – or maybe more we have to start to looking for problems in misalignment in between the gearbox and the propeller shaft.   Problems with the gearbox and we must have these problems sorted out before we advance any further.

As soon as we are happy  {-) and we have the motor running between ½ - ¾ of an amp we can go and get the model’s ‘bum’ wet – aye, the big test tank – stick the model in the test tank – apart from checking for leaks, first job is to place the battery in the position in the hull; and, then ballast it down to its waterline with your chosen set of weights.   I am lucky; I have a bit lead left over from the Church roof down the street  8) so, we ballast the hull down to waterline level.   Sometimes it is adviseable here to have two pieces of cable to make up an extension.  This is because multi-meters or amp meters do not like being dropped in water  :-\ yes I have done that myself,  balanced the amp meter on the model and its fallen straight off into the water.

Anyway, we need to take the reading now – of how many amps the motor is actually drawing whilst under full load.

So, just with the amp meter connected; in circuit with the battery and the motor; this will give us the total amps at full power - the motor is consuming, driving this propeller and in my case it was 5.8 amps.  For those who like it spot on, we will just say – what we have to take into consideration (although the motor is using 5.8 amps) when she is actually running free and moving and not being held, the amperage will drop slightly; only slightly though.  So, we have a reading now of 5.8 amps.

We are going to round the 5.8 amps off to say 6 amps.  Its back to the worktable once again, we need something now between the battery and the motor to control the speed.

In olden days and still today sometimes we used to use:-

•   Bob’s boards –
•   the fixed resistance type boards (where you had a series of resistors of different values giving you different speeds);
•   Resistant wire controllers, which looked like the old fashioned bar-type electric fire (those ones with the elements showing);

These types are semi-mechanical – where you require a servo to adjust them; through a mechanical linkage. 

Today though the norm is to use a purely electrical speed controller, and, for those who wish to have an easy description of how these work – they work on switching the electrical power supply ON and OFF lots of times per second.   So, if the switch is switched on all of the time; the motor is running at full belt – flat out – with full power from battery.  But, as you commence decreasing the speed, what happens is the speed controller begins switching ON and OFF – the more times it’s being switched OFF in a given set time, the slower the motor is going to go.

So that is an ‘easy’ description of how an electronic speed controller works.

What we need to do is to determine what size (as in how many amps) speed controller we require.   Now, maximum amps free running the tug is going to use 6 amps.  So, that was with me holding the tug stationary in the test tank, allowing the motor to thrash round at full belt.  So, if I am towing something that stops the tug dead in the water; I know it is not going to pull more than 6 amps.  In theory then what we require is a speed controller to handle double 6 amps i.e. 12 amps.   The reason I have doubled the amps that I require for my speed controller (and also a lot of other people do that too) is for a safety margin.  The unforeseen – a plastic bag floating in the water which gets wrapped around the propeller; the occasional lump of weed; and that dreaded swan feather; all get mangled around the prop.  Insufficient enough to stop the propeller dead, but sufficient enough to take the motor into what is called the ‘Stall amperage’.  The stall amperage is where the motor has been stopped physically whilst still under load.  In the case of the 550 it’s in the terrifying region of between 45 and 50 amps – these are the amps the motor stops at.

If we are to physically hold the motor stationary whilst the power was still being supplied, we would start to see smoke either from the wiring, or the motor, or worse case you would see your batteries EXPLODE and the WIRING BURSTING INTO FLAMES so, to prevent this, we could, if we required, fit a speed controller which is capable of handling 50 amps.   To be honest though, a bit of unnecessary expense and a bit overkill, for this particular model anyway.   What we do the safeguard this is add a fuse in line between the battery and the speed controller.  Now, our speed controller I am going to use a 10 amp one – protected by a 10 amp fuse,  So if the situation does arise where the propeller is stalled and stopped, before it does any damage the fuse WILL POP.  A 20 pence fuse is a good deal cheaper than a £30 speed controller or in the worse scenario watching your model BURST INTO FLAMES.

Electric Speed controllers then – there are literally dozens on the market today; and, as they say THE CHOICE IS YOURS.  But, before you go away handing out money – a couple of pointers which have taken me a long way:-

Although today’s trend is to ‘Purchase the cheapest we can because if it goes wrong, we can throw it away’ because that is the way a lot of cheap imported speed controllers are built nowadays;  it is a bit of a heartache when you know – you have fried the speed controller yourself by a silly mistake – by getting the wires mixed up and when you read the small print – you are not covered under the warranty for that and, I do not think there is not a modeller on this earth who can put his hand on his heart and say – “I have never made an error by mistakenly picking the wrong wire and connecting it up”.  :angel:  This is one of the reasons I try to purchase from our ‘home-grown’ industry.  Because, as some will tell you on this forum, there have been one or two occasions where I have picked up the telephone and spoken to the manufacturer and said “Hands up – I have dropped a clanger – can you help me?” .   Once or twice I have had the reply “BLOOBS – A FULL TEAM OF DOCTORS AND NURSES COULDN’T HELP YOU MY SON!!!!”  ::) But, it will cost you the postage and the replacement is always there for the next morning.  O0  You try and find that response from one or two Companies from abroad. 

So, I do like to build ‘kit’ speed controllers and, the particular one for this model I chose P79/79S CONDOR 10/2 SPEED CONTROLLER.   Kit build, I am going to include a couple of photographs because there are on this Forum kit building speed controllers and switches – so you could follow those threads if you wish.

Now, last but not least; the wiring side of things:

•   The motor has been what is known as ‘suppressed’ and for anyone requiring further information on suppression the subject is well-covered on other threads.

•   The supply wires from the speed controller to the motor are led and fed down one side of the hull; well away from any signal carrying wires.   This is what is commonly known as ‘The dirty side of the hull’.

•   On the opposite side of the hull there are the ‘clean wires’ and these are the wires that carry the power supply and signals to your servo and your speed controller and also extra units which you may wish to add in – such as switchers for lights and radar working.   These lead to your RX radio receiver which is on the clean side of the hull.

Following this practice helps to eliminate SOME OF THE electrical interference which can be troublesome at times. 

One picture will show the layout of the speed controller along with the RX mounted at the front (bow) of the hull.  The other pictures show you what you will find when you purchase a kit speed controller – from YOU-KNOW-WHO   ;) and you can see these are the basic tools I used to assemble the kit and lastly the assembled kit, but, without the casing – JUST SO YOU CAN SEE WHAT THE INTERNALS are like.  O0

Aye
John e
Bluebird



Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 15, 2008, 08:57:25 pm
couple more pictures - parts from the speed controller

 O0
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 15, 2008, 08:58:42 pm
Leather jacket required  {-) {-) {-) {-)

aye
john e
bluebird
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: John W E on January 30, 2008, 07:28:57 pm
hi all

Time for a new plan and then a new build.

aye
john e
bluebird
Title: Re: TUG CERVIA HULL BUILD by Bluebird
Post by: Martin [Admin] on March 23, 2008, 09:44:43 pm

Please post your questions and comments here::
 Q & A - TUG CERVIA HULL BUILD by Bluebird    (http://www.modelboatmayhem.co.uk/forum/index.php?topic=9788.0)

(Please don't post here, they will be moved.)