Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1] 2 3   Go Down

Author Topic: TUG CERVIA HULL BUILD by Bluebird  (Read 33600 times)

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
TUG CERVIA HULL BUILD by Bluebird
« 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
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #1 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;

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #2 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.
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #3 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #4 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #5 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #6 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. 

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #7 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.
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #8 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #9 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #10 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #11 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.
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #12 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.
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #13 on: December 28, 2007, 01:07:36 PM »

AND SOME MORE PICS.....showing planking

 O0
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #14 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.
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #15 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #16 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #17 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!

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #18 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #19 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
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #20 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #21 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #22 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.   

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #23 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.

Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,512
  • Location: South shields
Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #24 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.

Logged
Pages: [1] 2 3   Go Up