Masterclasses > DRIFTER/TRAWLER FREDERICK SPASHETT

PLAN BUILD NUMBER 4: DRIFTER/TRAWLER FREDERICK SPASHETT

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John W E:
FREDERICK SPASHETT – THE DRIFTER TRAWLER BUILD
Have you ever thought what makes us contemplate building a certain model?   Those who are new to the hobby will be drawn into the pastime for one reason or another albeit for pure relaxation or whatever reason.

We will find, once we are established in this hobby, that we have a preference – some prefer modelling Warships, some prefer tugs, some prefer liners etc.

I would personally consider myself, as, what they say a Military Naval builder – as the majority of my models consist of some form of Military vessel.  Every now and then; we as modellers see either a photograph or a plan/actual model of a particular vessel which is not in our chosen field and it triggers something off inside of us – which either brings back memories or we say ‘Oh that is a nice boat’.   This is how the plan for this trawler triggered me – it brought back memories of standing on the quayside of the River Tyne watching the activities on the North side of the River – at the Fish Quay – in my younger days there were lots of boats there, and it was a hive of activity – the sounds and certain smells never go away from the memory  so this is why I have chosen this plan as a build plan.   Because, it holds very special fondness for the past-times and happy memories….

For those who have some experience in building from plans; I suggest you may skip this next part – as this section is dedicated to those who are new to the plan building, but, not new to the field of modelling.

We are going to have a look at the Plans and we are going to have a little insight of the Person who drew the plans.

We will begin with the draftsman, James Pottinger Esquire; James was the draftsman for this particular model plan.  To date James must have drawn approximately 150 plans and he has been doing so for over 30 + years.  Amongst his plans, he has plans for cargo ships, tugs, fishing boats, yachts and other various types.  So, from his selection of plans there is a wide variety to choose from.     There is not a complete list of all of James’ plans – you have to be a bit of a Sherlock Holmes. Do a little bit of digging in the Marine Modelling Magazine and also plans published via the Model Boats Plans Services, there are also several plans published in the Model Shipwright magazine.   So, if you are unable to find what you are actually seeking from the above list; you can contact James Pottinger via email or post details nearer the end of this build thread.

James Pottinger is an engineer by trade and has worked in several fields of the offshore industry and also, sea-going industry – and this shines through in the plans he prepares for us.

So, we know we are going to build from a good accurate set of plans here – at this stage then let us take a look at the plans, to which I have included a scan of a set of plans which can be obtained from the Model Boats Magazine.    This scan, along with the article, comes from the Model Boats Magazine – September 1977 – to which James Pottinger presented an article for the magazine.

John W E:
There are three main views on the plans of the vessel; the main one is the side profile or elevation as it is named on the plan.

Below it there is what is called the deck plan; and, to the left hand side, is the body plan.   Scattered around there are other small sketches of the Captain, bridge, wheelhouse top and there is also a view of the front of the wheel house & scattered around the rest of the plan are various other items such as the typical deck section and also a suggested method for gaining access to the hull for modelling purposes.

We will concentrate firstly on the 3 main items which concern us on the plan.

The Body Plan

This shows us the shapes of the frames, at certain sections on the elevation plan.  You will see they are numbered; they go from zero to 9½, and, if we look along the side elevation of the plan, you will see the numbers repeated there.   These numbers show the positions of the frames on the side plan.   You will also notice that the deck plan is also in line with the elevation plan.  The numbers can be transposed straight across to the deck plan, giving us the desired total widths of the frames.

If we revert back and have a look at our body plan, you can notice that there are horizontal lines drawn through the frames; and these go from number 1-17 and these horizontal lines are what are known as the water lines.

These lines are of some use to some modellers – to help check the trueness of profiles of the frames.   However, you will notice that these lines have not been repeated on the elevation plan so they won’t be of as much interest to us in this build.

John W E:

We need to know now what frames and what positions we are going to trace off.   So, first of all, you will see the baseline – Number 1 on the body plan, does not actually start at the very base of the keel.   It actually starts at the plating rebate line, which is where the actual plating on the life-size vessel meets the keel.  So, we take all our vertical measurements from this rebate line.   

We draw in/draw over the centre line of the frames, this is the line which divides the forward looking frames which is on your right-hand side/starboard side as you look at them, and, on your left-hand side/port side are the rear facing frames as though you are standing in the dock looking at the rear of the life-sized vessel.

We have therefore drawn over our centre-line which will go beyond the height of the total frames; to this we then draw a horizontal line 90° to our centre-line.   This will become our building board line.
On my particular model, I drew this line ½ inch above waterline number 17.   

Now have a look at Scan A and this is of the body lines.   I have marked on various items; which we will be concerned with.

We will start off with the very base line; at the bottom of the frames.   This will be called the plate rebate line.   This is where we take all of our sizes from for vertical heights (this particular line).  Then, when we look at the centre of the frames, we will see that there is a centre line drawn vertically and at 90° to the plate rebate line.    Either side of this centre line there are six frames drawn – on the right hand side – numbered from 9 ½ to 6   and on the left hand side of the centre line there are eight frames drawn numbered 0 all the way through to number 5.   

Don’t forget left hand side – PORTSIDE – as though we are standing in the dry dock looking at the vessel from the stern – these would be the frames we would see.

On the right hand side – STARBOARD – side – if we were standing in the dry dock we would be looking at the front of the vessel and we would see the starboard/front frames of the vessel.

Also on scan A you will see we have marked on the building board line, which is – as I have mentioned before – on my particular build is approx ½ inch above waterline 17.   This building board line is parallel to the plate rebate line.

Next we have marked on the bulwark top edge and this is the line which represents the very top edge of the bulwark.   Below that, we will see a deck edge line; which is ‘arrowed’ in – this line represents the level of the deck but only at the edge of the frame.   So, where this line intersects the frame line, this is the height the deck is at that particular frame.   This line takes in no account of the level of the deck at the centre line of the hull; this is only the level at the edge where the line intersects the frame.

Now, if we look at Scan B you will see the same body plan but, only with 2 arrows drawn parallel to the centre line.   This is to aid – determining the height of the deck and also it aids us for when we come to trace.

You will see at the outer edge of the frames, there is a vertical arrow marked as A – now, I have taken frame 7 as an example.   You will see there is a line drawn parallel to the base line through to the centre line.  Where the deck edge intercepts frame 7 that height is transferred to the centre line.   This gives us the height of the deck; however, it doesn’t take into account for camber.

This is as far as we will talk about this particular scan for the time being.

John W E:

I think at this stage now, we will begin to look into the actual build of the model and we will start with some requirements – such as:
What shall we make the vessel out of?
What motor shall we put in it?
What electrics do we require to go along with the motor?
Are there any special hardware/fittings which we need to purchase?

Materials we are going to construct the model from:    Plywood; some GRP (glass reinforced plastic); some Obechi strips; and, also, for the planking we are going to use Lime strip – plus some maple for the deck planking.

Some side notes about plywood – there are various types of plywood on the market – for home DIY use and also there is marine ply which is used in ‘real’ boat construction:  Modelling ply; as in light-ply and all these ply’s do have some uses.   Some of the plywoods have limited use to us modellers – such as – DIY plywood which is sold in a lot of stores.  This tends to be of little use to us, because, the inner material of the plywood tends to be of a poorer quality then the exterior veneers of the ply – they tend to peel off and split (when it is cut into narrow strips/profiles).

The marine ply as used in the life sized boat building – tends to be on the heavy side for modelling use.  Therefore, this leaves us with the plywood which we purchase from modelling shops/shops which will order in multi-veneer plywood.    I use a birch ply which is made up of 5 veneers – it is a lot more expensive than normal ply – but, this extra price does pay dividends – and the quality stands out when you are actually working with it. 

Now, what about the material we are going to plank the hull in, if we are making the frames from plywood; normally, my preference is to use Obechi planking.   This can be bought in a variety of widths and thicknesses.   I normally use 1.5 mm thick planks, but the width of the planks depend solely on
a) Size of the hull we are building as in length and

b) Shape and the width of the hull

If we are building a hull with very few radius’ in the width of it; as in a vessel with a hard chine construction; we can use relatively broad/wide planks; going up to something like 1 inch in width.   But, if we are building a ‘round’ sectioned hull or in correct terms a displacement hull  where we encounter radius’ on the sides.   This is where we need to reduce the width of the plank to fit the average radius of the hull.  If we try to plank a ‘rounded sectioned’ hull with broad planks – we would tend to end up with a hexagonal affect or a 50 pence piece affect.   So, what we must do is reduce the width of our planks – and we can then faithfully follow the radius in the framework of the hull.

On this particular build I decided to move away from Obechi and try using a relatively new material to me – I am going to use LIME strip planking this time. And the thickness of this Lime strip is on average 1mm to 0.8 mm thickness; and is of 0.8 mm width.    Before I actually used this, I cut a short section off to experiment with it.   To some extent it is slightly better than Obechi to work with – I found when I had put it in boiling water to soak – it actually became more flexible – hey a lot more flexible than Obechi – and it didn’t split either – sometimes Obechi splits across the grain.     Another plus point for the Lime strip is that the majority of the material I had, the grain runs true to the length of the plank – when I have been working with Obechi sometimes, I have had one or two strips of Obechi where the grain has ran diagonally through the width of the plank; rendering it almost useless to use.

I am using 1/8 square Obechi for the stringers.    I have used a /¼square of Obechi for planking support either side of the keel.

The other piece of material I am going to use a lot later on in the build, this is maple and this is going to be used for deck planking it is 0.5 mm thick x 6mm wide – and this material will be discussed later on in the build.

This then, takes care of the wood materials.   Glue – I am going to use a ‘new to the building’ – it is TITEBOND II – basically it has the same characteristics as Evostik Resin W which is what is classed as ‘weatherproof’ and, the only difference between it – I can see – is it is yellow coloured and not white.    It actually does dry yellow too.

We now move on from the glue to the materials we are using for the fibreglass work; the resin was purchased from an Auto shop – in the case of UK – Halfords store.    The manufacturers of the resin are DAVIDSON’S and this is just a standard ‘lay up’ polyester resin and along with this resin is the appropriate hardener, which is a ‘pinky’ coloured paste which comes in a foil tube.

Tissue matting – I have is what is called a ‘Finish tissue matting’ which resembles toilet paper to look at  .

The above listed materials are basically what are required to manufacture the hull.   We now need to move on to the hardware materials.   :-

The propeller shaft propeller shaft I decided to use this time was a standard one I purchased – 4mm shaft diameter x 200 mm long.

The rudder will be built from the plan and made up of 1/8 brass rod; 2 lengths of 1/8 ID (internal diameter) brass tubing.      Also, 2 small pieces of 1/8 ply the same size as the rudder.

The motors; when we discuss motors for particular models we could end up having a long discussion of to’s and fro’s of the size you require for the model; some people do have preferences as in they like to use motors which come from automobile seats from the scrap yard; also there is to take into consideration the power which is required and whether it should in fact be direct drive or through a gearbox.    Bearing this in mind, what I have done in this build is built in a provision, for those who wish to use direct drive – they may with their choice of motor.   This is my choice of motor which I am now going to describe.

The motor I have chosen is a Graupner Speed 500 – along with this, there is an MFA Olympic belt drive gearbox and which has a ratio of 2 to 1 – meaning for every 2 revolutions the small cog on the motor makes  -  it turns the large cog (which is connected to the propeller shaft) once.  Giving us that 2 – 1 ratio.  The reason I have chosen to include a gearbox is that the brushed electric motors of DC current have their best efficiency at the top end of the RPM and operating voltage.    In other words it is most efficient when it is running at 6 volts and approx 17,000 RPM. 

We will be driving a 45mm three bladed propeller; and if we were to direct drive this propeller at 17,000 RPM we would be looking at astronomical amperage.   Somewhere in the region of about 15 – 18 amps; 

This is not very good when one considers using this set up for a 6 volt 4.5 amp battery – it isn’t going to last very long and the battery etc., is going to get very hot.   However if we are going to use the same motor and put the drive through a gearbox of 2-1 ratio – it means the motor may still run at 17,000 RPM, but the prop shaft will only turn at 8,500 RPM which is acceptable for the propeller that we propose to drive.  Doing this will also bring our amperage down and therefore making our duration on the water a lot longer.

We will go into greater detail of choosing speed controllers later on in the build – so – we have now outlined some of our requirements; and the next thing is to commence and actually start the build.

We have spread the plan out and familiarised ourselves with it and we are quite happy – so first of all what we need to do is somehow transfer the outline of the frames; from the body plan to our building material.   This can be done in several ways; we can trace each individual frame off using tracing paper – we can photocopy the body plan, cut out the individual frames from photocopied images and stick them onto our building material – we can use an old method which is still used quite regularly by some builders and it is called the pin and prick method.  This is where you use a dressmaker’s pin to pinprick the image through the plan onto the building material.   You then remove the plan and you go over the pinpricks with a pencil.   I suppose it does have some advantages, but, as yet I cannot find one.  But, let’s not knock it – it is still a method.      The other method is a carbon copy method similar to what typists sometimes use; where you place carbon paper on top of the building material – place your body plan over the top of the carbon paper and you draw around your frames with a pencil and this in turn reproduces the image from the carbon paper onto the building material – and – as they say – THE CHOICE IS YOURS.   

My preferred method is the tracing method – and what I do is photocopy the body plan; pin the photocopy to a piece of plywood ½ inch thick – approx A4 in size for dimensions and this gives me a drawing board type of affair – and I pin the tracing paper over the top.   

The first thing I draw in is the centre line of the frames; followed by the building board line which is in my case ½ inch above the waterline number 17.   If you have a look at the body plan you will notice that there are horizontal lines drawn through the frames and they go from 1 to 17 – now these lines are parallel.

You will notice that waterline number 1 does not begin right at the base of the keel; it actually begins at the plate rebate line.   This is where, on the life sized vessel, the outside steel plating is joined to the keel.   This rebate line, on this particular build, is used throughout the plan as the base line.   So, when you look at the side elevation do not become confused with the line which is drawn underneath the vessel with the numbers on.   It is the 2nd line up from the base of the keel where all of our measurements are taken from.

We get back to what we are doing – we are going to trace our first frame.   We have traced the centre line and we are going to trace the building board line above water line number 17 – DO NOT FORGET the building board line is parallel to all of the waterlines.

So, the next thing is to do – to determine the height of our first frame, which is going to be frame 9 ½ - now as we look at the body plan and I have put 2 scans on to show this – we have running round the top edge of the frames our bulwark line.   This line represents the very top edge of the bulwark which runs right around the vessel.   Below this line we will see another line which runs basically parallel to the bulwark line and this is the deck edge line.   This is the line which represents the very edge of the deck and also represents the height of the deck, where it actually crosses the frame – so if we take frame 9 ½ first to trace – we trace our frame up to the deck edge line.  We then take this height where the frame reaches the deck edge line and transfer this total height from the rebate line over to our centre line.  This gives us our height of the first frame – bear in mind it doesn’t take into account for the camber of the deck.   This gives us a flat deck.     We will come back to the camber later on in the build – I am not going to include cambers onto the frames because it has caused certain confusion and problems in the past – so all of the frames are going to be ‘flat decked’.   We have traced frame 9 off and what I personally do is take the tracing paper off turn it over – reposition it back onto the body plan – realigning the centre line and the building board line along with the body plan line.   I then redraw the frame and in this case it would be frame 9 ½.   So, when you look at the tracing, which you have done, you have traced a full image of the frame albeit that one part of the tracing is on the opposite side of the tracing paper.   I then draw in my support legs which are going to support the frames on the building board.  These normally represent 2 parallel lines, approximately 1 inch apart; which go from the deck of the frame to the building board line.

Now, I have learnt in the past through experience to draw each frame individually on a separate piece of tracing paper, which I did do in this build.  All 14 frames – so at the end of the day I had 14 pieces of tracing paper with full frames drawn on them along with building support legs.

The next stage is, to go to your side elevation plan.  What we require to do is to trace a section of the keel from say….frame 8 all the way up to the full height of the bow.   Don’t forget, we trace the rebate line.   We then need to trace a stern section from say frame 1 ½ all the way around – and all the way up the stern of the vessel the full height – and even tracing the propeller opening.   You may, if you wish, even trace the rudder.   However, on this tracing also trace the centre line of the propeller shaft and also the centre line of the rudder shaft.

John W E:

We now move on and we require our building material now – which we are going to cut our frames and keel from. As I have already stated, I am using 6mm 5 ply.   

First procedure – pick the long side of the plywood ensure that it is true with a straight edge – the very edge of this plywood.   Then say, 6 inches from one edge of the plywood that is the short edge, put a pencil mark and draw a line half way across the plywood at 90° to the long edge.   What we are actually going to do is draw the frame positions out along the edge of the plywood. 

So, we start off at the mark we have already put and we call that Zero.    We take the distance from our plan for the first frame which is frame ½ and from position 0 we mark this frame position – with a line going at right angles to the long edge.

We carry on until we have marked all of the positions of our frames along the edge of the plywood.  The next stage we do is we take the tracing we have made for the bow of the vessel – we align this tracing up with the frame markings along the edge of the plywood.   So, if you have marked off on your bow from frame 8 – you should align frame 8 on your tracing with frame 8 which you have marked on the plywood and then transfer the bow shape onto the plywood – through the tracing paper.   Repeat this procedure for the stern and don’t forget to mark in the propeller aperture and also the propeller shaft and rudder centre line.  Tip here – when we have finished doing our tracings in pencil on the plywood – go over them with a biro – this prevents the pencil marks fading into the plywood.

Now the next stage I do is to take all the tracings of the frames which I have made and I lay them around and on the plywood so I can achieve the best positions for all of the frames on the plywood., making sure that I don’t overlap the images – when we are happy we have achieved the best positions for all of the frames, we then transfer the images from the tracing paper onto the plywood/building material ensuring that we trace the full image – and not leaving anything off.

This is the advantage of tracing the full frames onto the tracing paper, in the beginning. 

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