Masterclasses > CERVIA Tug Build

TUG CERVIA HULL BUILD by Bluebird

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John W E:
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

John W E:
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;

John W E:
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.

John W E:
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.

John W E:
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.

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