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Author Topic: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird  (Read 29543 times)

John W E

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63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« on: March 22, 2008, 08:42:41 PM »

PLAN BUILD NUMBER THREE

63 FOOT RAF AIR SEA RESCUE LAUNCH
COMMONLY NAMED ‘THE WHALEBACK’

In this plan build we are looking at a slightly ‘different style’ of building the model hull.  Also, some slightly different materials in the process of building the model hull; and we are delving into the areas of a ‘lot more research’.  By a lot more research we will be researching the history of the full sized vessel to help us in our build.

So, let us cut out the waffle and begin to look at the plan  :)

The plan comes from, yet again, the Model Boats plans catalogue and it was originally drawn by a gentleman by the name of John Pritchard.   John is well known for his drawings of coastal craft such as MGBs, MTBs, Air Sea Rescue launches and so forth.  Along with these plans; I have two articles which were written by John for the Model Boats magazine, one in the year July 1975 and in those days you could purchase the Magazine for 25 pence – eeee and I used to have a full head of hair then  {-).   John also revamped the article and it was reprinted in October 1981 – the magazine had gone up to 60 pence then!!!!

In the October 1981 issue, there are a scaled down set of plans identical to those which I purchased from the Model Boats plan company.
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #1 on: March 22, 2008, 08:46:04 PM »

So, let us have a look at the plans.  What are the plans going to tell us?   Well, they are graded on the grading system at 4 star **** for the experienced modeller.  When we look at the plans we see at the top there is a side profile drawing of the boat.   To the right of the side profile there is a front view drawn of the boat.

If we look carefully and can make it out; there is a baseline and a water line running parallel through these two drawings.  We need to note this for reference further on.

If we look down from the side profile drawing, we will see a deck view of the vessel; underneath that there are our side profile line drawings.    On this particular drawing which is the one for the time which will concern us; you will see it has been divided up vertically by 7 lines; drawn through the hull.   It has also been divided up 8 times horizontally.   These horizontal lines are marked off as ‘water lines’.   Zero water line or we will call it the baseline also corresponds with the line of the top drawing on the side profile.

So, we know any measurements taken from this baseline will not only correspond with our line drawing; but, it should also correspond with the side view of the vessel.   The vertical lines through the line plan drawing represent the frames or in our case they are going to become our ‘RIBS’.  If we look below the side profile drawing; there is a deck profile drawing.  This again has been divided horizontally and vertically and this time the horizontal lines are marked B1, B2 etc., etc., and these represent what they call ‘BUTTOCK LINES’.

For the purpose of our build; we do not need to really concern ourselves with that too much – we only have to be concerned (for this time being) with the vertical lines which are representing our frames and also our water lines.  If you study the plan closely you can see and this is just for pure reference and information only – the Buttock lines represent, or should I say, they are the squiggly lines drawn through the hull on the side profile.  When I say squiggly they are the lines that go from the deck edge down towards the keel and back up to meet the deck line.

Now then, if we move across the page from the line profile drawings; across to our right hand side of the plan, you will see there is a stern view drawn of the vessel and also, underneath that, there is a line drawing of the frames or ribs.   This line drawing has been divided up again by horizontal and vertical lines and you will see on close inspection – if the scan allows – that the lines are numbered and lettered and they will correspond with the side profile and deck profile drawings.

Now for the time being, what we must do is concentrate and familiarise ourselves with these three drawings, the frame drawings, the hull and the deck profile.  We then know and we can picture in our minds exactly where every frame fits or is located on the profile drawings and on our deck line drawing.

When we are happy with that; we next have to look and say to ourselves – okay – how are we going to power this model? This is because, on close inspection you will see, there are no propeller shaft locations drawn in on our line profile – nor is there any rudder positions indicated.   Our first job is to find the location and transfer these from our side profile drawing and stern drawing to our line drawings.  Also, at this stage, we have to consider – are we going to make the model – a working triple screw model; or a single screw model?  (The screw means propellers in this instance).

For this build – it’s going to be TRIPLE SCREW – i.e. hopefully blinking fast.  ;D

So then; we can either – with pencil and ruler take measurements from our hull profile drawing (side hull) for the position of the propeller shafts and rudders and then transfer these to our line profile or we could actually trace them using tracing paper.   

I opted to transfer these with pen and ruler; and I didn’t only transfer the measurements to the side and deck line profile drawing; but, I actually transferred it to the frame profile as well.  The reason for me doing this on the frame profile will become evident later on in the build.

As we stand back and have another look at the plan, it does give rise to a lot more questions which we have to answer.  As this plan doesn’t give any indication of what materials to build the hull from or what motors to power it; we have to find these out for ourselves.   

We also have to work out what scale we want to build this model too, at the scale the model is drawn on the plan which is ½ inch to the foot; this will give us a model of some 31 inches long.  This will be a reasonably sized model, easy to handle and will be fairly light and with today’s generation of brushless motors and LiPo batteries this will give us a startling performance on the water AS LONG AS WE KEEP THE HULL FAIRLY LIGHT.

When I originally purchased this plan and built the hull a good while ago; we didn’t have the brushless motors technology or even the LiPo batteries as we have today and when I built the hull – I made it to the scale of ½ inch to the foot – I powered the model with three Rocket 400 motors; with something like 15 mm diameter propellers.  They were the largest propellers I could fit in and this model would not perform – it used to waddle round – similar to a lame duck   and to increase the size of propellers I would have to do major surgery on the propeller shaft lines.

Armed with the above information, I was looking to build this model using brushless motors.   This is when the first (shall we say) major setback hit me – but the price did!  :)  Two hundred pounds sterling is a lot of money to try and raise from the Banker  {-) when the only thing you can say is well they are very good batteries, motors and speed controllers.  The Banker then says the new bathroom suite will only cost us Three hundred pounds sterling and that is more important – so, I did lose that argument.   We are therefore back to the drawing board.

Next thought was, make it 1/12 scale – 63 inches long – 17 inches beam and it makes a nice large size model.  The only set back there was ME physically.  So I therefore scaled it down, I couldn’t have the motors I wanted; the scale I originally wanted to build it would have been too large for me to handle and I eventually scaled it down to 5/8 inch to equal one foot.   This is what the model is going to be built at – at this scale – we can comfortably manage 3 MTroniks – Vision 600 motors and also 3 NiCad packs.  This will be the power.   Also, we can comfortably accommodate 30 mm – three blade propellers on her.  This should give her a lively turn of speed  :)

That takes care of our ‘rough’ power requirements and we now must look at the material we want to use for the building of our model.

This particular shaped hull, lends itself perfectly to what is known as ‘Diagonally planked’ hull.   Ironically the original boats were double diagonally planked and in between the two planking layers there was a layer of Calico canvas.  The planking, although we could longitudinal as we did on the Cervia build, we are going to opt to diagonally plank this hull.   In actual fact, it will be double diagonally planked.   The inner layer of planking is going to be Obechi and the outer layer of planks is going to be Mahogany.

That takes care of the ‘skin’ of the vessel – but what about the framework to hold the skin.  Here we are going to use a high grade birch ply – of 1/8 inch thick for the construction of the frames; the keel & the motor mounts and several other mounting components.   This particular birch ply I purchased from a Company www.mantuamodel.co.uk – you will find that it is slightly more expensive than the standard modelling birch ply because it has six veneers to make up its thickness.  This plywood is extremely strong, for its thickness, and I believe they use it a lot in model aircraft – but hey its ideal for the purpose we are going to use it for  :) so now we have outlined a good few things and we are quite happy with the plans – we can really begin to proceed with taking information from the plans and applying it to our building materials.    Since we are going to scale up these drawings to 5/8 of an inch to the foot – my first plan of attack was to photocopy the frames drawing, which I did do, and that increased the drawings to the appropriate scale i.e. it worked out that they measured about 10.5 across the widest point of the boat and this equated to 136% approximately.  This was fine, because I had to allow 1/8 inch for planking; so, I printed the frames off at this scale.   I then moved on to increase and photocopy the lines side profile.  This is where I hit the first snag.   The overall length of the hull should have worked out in the area of 39 inches or thereabouts.    47 inches was totally unacceptable and that is what they came out at.  O0 So plan B was scrapped on enlarging the side profile on the photocopier.   

Plan C was to draw out on the 1/8 plywood we were going to use, the side profile at the correct scale.   This I did; by starting off drawing a base line; to correspond with the base line on my plan; then followed by the water lines drawn parallel to the baseline at the correctly spaced intervals for the scale.

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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #2 on: March 22, 2008, 08:49:28 PM »

This was followed by the vertical frame spacings drawn onto the plywood on the correct place.   I then plotted out the shape of the keel onto the lines which I had drawn.  This gave me a side profile of the hull to the correct scale.

Then the next step in the procedure was to turn back to our enlarged copy of the frame drawings; mark in the centre line between the frames and the baseline and then add our building board line which is parallel to the base line and is 1 inch above the tallest frame (I did this on the Cervia build).  This baseboard line, as we know, represents our building board.

Every frame we trace off now, we also trace this building board line; plus, two legs or 4 lines drawn down from the baseboard line, touching the deck line of the frame we are going to trace.   These lines become support tabs – and support our finished frame on the building board.     

On this particular model, we traced all the frames out first; on separate sheets of tracing paper; we then drew the opposite side of the frame onto the tracing paper – so in fact we were producing the full frame per sheet of tracing paper.  The reason for this is the frames are large (some being over 10 inches across and over 7 inches deep) and we needed to shuffle the frames around on our plywood to ensure that we could accommodate them all onto that piece of wood without being too wasteful of the plywood.   It took me several attempts and the best I could achieve was having one frame slightly cut into the top of the keel which does no harm apart from the cosmetic value of the frame.

Sometimes it is advisable to use this principle of tracing full frames out, rather than half frames – when we know we have limited materials.

Once I was happy – I began to mark out the centre areas of the frames; requiring a light hull I kept the thickness of the sides of the frames as thin as I dare possible.   In some cases the side width of the frame was just over ¼ inch wide; also, on the bottom areas of the frames, I have left slightly thicker but you will note that holes are cut in and these have several purposes.  Apart from making the frame lighter, they also give passage of cables between frames; also, if needs be the movement of water  :)  between frames HOPE NOT ;-)

Also you will see, as well I have drawn in the motor mounts; and also the servo mounting.  These are marked in, if you look closely, in the centre of the frames which will be cut out later on.   Once we are happy with all that we have drawn onto the plywood, and we have ensured that we have copied all of the frames correctly; and we are pleased we can proceed to cut the frames out.   We have mentioned this procedure before, but, for those who are reading this for the first time – I prefer and this is my personal choice – not because it’s any better or any worse I like to use a hand fretsaw to cut all my materials out with.   The other thing is, when we cut our frames, keel and motor mounts out try and cut out at least 1/16 of an inch away from the finished line.  Personally I do not try and cut the frames straight out, size for size; I try and cut the plywood /frames out into manageable chunks.   In other words, one piece of plywood which I have cut off may have two frames drawn on it.

At this stage, once we have cut the frames out we sand them to near enough the lines; leaving our line left on.  When we have cut all the parts out i.e. the frames & the keel; note at this stage I have not removed the centre of the frames yet.  This will be done after I have cut the notches for the keel fittings.   This is what I did next.  O0
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #3 on: March 22, 2008, 08:52:24 PM »

I cut out the notch for the first frame in the keel and then I cut the corresponding notch out of the frame.   When I cut the notches out; I tend to make them a ‘slack’ fit whilst working with thin plywood and when I say ‘slack’ I don’t mean a RATTLING GOOD FIT  :) aye to give you an example if we mate the two parts together – i.e. the frame and keel and then pick the keel up – the frame should just barely stop in place.   If I shook the keel, the frame would in fact drop out.

The reason I do this is when we come to do the final assembly, and we apply the glue to the joint I have had situations where, for some unknown reason either the timber has expanded with the glue or just with adding the glue, the joint becomes extremely tight – and forcing the joint in place can in fact smash the frame.  So, to overcome this, we make the joint a little bit on the slack side.

So, we have cut the joints out for the keel, and the next set of notches or joints to cut out are the ones to take the motor mounts.   These notches are parallel to the keel notch, either side.   Then, when I have cut them out, I removed the centre of the frames.   I then finish dressed with sandpaper the insides and outsides of the frames – set them to one side and now we have to work on the keel itself.

The keel has the centre prop shaft running through it, so, we must cut it into two at an angle and this is where we require our information from the side profile line drawing, to give us the position of the centre propeller shaft on the keel.

Once we have marked the propeller position out, we cut the keel and then I added ‘packing pieces to either side of the keel’ to make it the same width as the propeller shaft in other words the propeller shaft was 6mm and so either side of the keel which is roughly about 4mm thick, I added one piece of 2mm plywood either side of the keel giving a total thickness of 6mm.   I then cut another two pieces of 2mm plywood twice as long as the tapered cut through the keel; and these pieces become the cheek pieces that hold the keel together.   I have included a photograph and also, if we are unsure of exactly what it is, we did a similar thing on the plan for beginners; so this takes care of our keel assembly.   The only other thing was, where this propeller shaft cheek assembly was on the keel, bang in the centre of it is mounted a frame.   So, the notch in that frame had to be widened accordingly.   The next stage in our build we do a dry fit of all the frames to the keel, checking that they all sit in position properly and there are no frames out of alignment.

Once we are happy with this setup, we can now start marking off the notches for our chine stringers and our deck stringers.  What I do with these, is, I use a scrap piece of wood, the same size as the chine and deck stringer and use this as a template when I cut the notches out.  For reasons of not wanting to make big mistakes and drop clangers as we all do, when I cut notches out I cut all the chine stringer notches out first, checking with a scrap piece of timber the same size of the chine that the notch is cut squarely on all of the frames,   when we have finished doing that – we will then move on to the deck stringers; cutting and checking as we go.  This to me does save embarrassing situations, where we have cut all the notches out and find we have cut some of them in the wrong place and IT HAS HAPPENED TO ME  :).

At this stage, you will notice that we have not marked out the location nor cut for the stringer notches this, I personally leave, until a little bit later on in the build.  So, the next stage in the build now is to manufacture a building board.

We will use the same principle and system for the building board as we did with the Cervia build.  One piece of chipboard preferably ¾ inch thick, two or 3 inches longer than the hull we are about to build – in our case the building board will be 44 inches long.  Ideally me building board should have been about 14 inches wide; but, I could only get a piece of chipboard that was 10 inches wide, so I made use of that.

0n the reverse side of the building board, I glued and screwed two lengths of timber down the length; which were 2 inches x 1 inch x 44 inches long.   This serves the purpose of preventing the board from twisting and distorting.  As a side note; I know I used chipboard, but, I suppose if you have it you could use thick plywood or even MDF (high density chipboard).

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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #4 on: March 22, 2008, 08:55:48 PM »

On the plain side of the building board we mark a line down the centre, and then this line is divided into spaces which correspond with the spacing on our keel for the frame positions.

At the frame positions, marked on the centre line, there is a right angled line drawn through at 90° to the centre line.   I then started to assemble the support blocks onto the frames ensuring that the support blocks also had a centre line on, which corresponded with the centre line of the frame.  I then began with the centre frame mounting this onto the building board.  Once I had checked that the first frame on the centre board was mounted at right angles to my centre line and also vertical – checking this using a set square/engineer’s square.   I moved on, one frame either side locating and fixing frames until I had all frames positioned and mounted onto the building board; apart from the last frame which is actually transom.  This transom is set at, I believe, at a 15° angle, the reason I believe – it’s a little while since I actually did this and I am just catching up on the writing.  :)

We now do our final check to ensure that the frames are square with one another and parallel – and when we were happy with that, the next thing is to insert the rudder servo mounting which I made from 1/8 ply and it is mounted mid-way between the 2nd and 3rd last frames from the stern.

I fitted the keel into position (with no glue – just a temporary trial fit).  When it was in place; and set home; ensuring it was sitting snuggly in all the frame notches, I laid a 3 foot steel straight edge along the side of the full length of the keel.  This was to ensure that the keel was not bent like a banana when viewed from the top – or looking from the bow down the length.

The straight edge was then lifted on top of the keel to ensure there was no hog/hump in it; when I was happy with that I removed the keel, I then repositioned it using glue.  The glue I used was EVOSTIK (water proof evo bond) and before the glue had set I re-checked the keel with the straight edge ensuring that it had not distorted.   When the glue had dried; I moved on to very carefully sand the frames to make sure that they were fair with one another.   I say very careful because anyone building a hull like this must remember that the frames are very fragile.   Where the deck stringers fit into the notches and also the chine stringers, on the first three frames in from the bow; the notches were angled with a file so that the angle faced the bow taking the sharp corner off the notch.

Next procedure was to actually fit the chine stringers; and then the deck stringers.   The deck stringers were laminated 1/3 of the way from the bow – two pieces 1/8 x 1/8 laminated together.   The last 2/3 to the stern were a solid piece of Obechi 1/8 x ¼ - the chine stringer was put in as a one piece of Obechi 1/8 x ¼ which was steamed, stuck in the spout of a boiling kettle, with me finger stuck on the switch and if there are any youngsters reading this YOU ARE NOT TO DO IT you must get a grown-up to help you.  BOILING WATER CAN KILL – if you are lucky it ‘just’ peels your skin off – SO TAKE CARE!!!

Happy with this, they were glued and clamped and then allowed to dry; and whilst these were drying, I fitted the 4 motor bearing mounts, these were made up similar to the keel; but, only in 2/3 lengths and they run parallel either side of the keel – 1 ¼ inches apart.  (Spaced roughly 1 inch from the keel).

These 4 lengths of timbers will eventually become part of the motor mounts; and supports of the batter packs and speed controllers.  I set the whole assembly aside and let the whole assembly dry overnight – not removing any clamps until the morning.

When I had removed all the clamps  I faired the frames in with fine sand paper and a sanding block – the sanding blocks were one large square lump of wood – about 12 inches long by about 1 ½ wide.   The other one was a scrap piece of waste pipe about 6 inches long and about 2 inches diameter – this is for fairing in where the hull flares at the bow.

The next stage was to add the stringers; the first four stringers to go in carry on from the front of the engine bearers to the bow and the way this was done - the stringer was laid over the top of the frames so it was in an even position and then temporarily clamped onto the frames; where the stringer touched the frames, it was marked with a pencil either side of the stringer.

When I was happy with the positioning of the stringers; and had marked the positions on the frame, I removed them and with a razor saw cut the notch out.    If you look at one of the photographs you will see how I set the depth of each notch, to stop me from cutting too far down.

Some of you may not be able to afford this expensive piece of equipment and also it is extremely difficult to get a hold of because an electrician doesn’t like giving up his electrical tape without a fight.    You guessed it a piece of electrician’s tape stuck to the side of the saw the correct depth in other words 1/8 of an inch from the tip of the teeth and when I reached the edge of the electrician’s tape that is when you know when to stop! SOMETIMES  :)

I cut inside the pencil marks, because – always remember it’s always easy to remove material, but, much more difficult to put it back in.

So, I ended up putting 4 stringers in the bottom of the hull; and 4 stringers in the sides of the hull.   Where the stringers on the hull bottom are relatively evenly spaced; the stringers on the sides are closer together towards the deck level.   The reason for this; there is a fair amount of flare at the bow and with the aid of the stringers it makes bending the planks into the flare a lot easier.

Now we have all the stringers fitted, we must once again give a gentle light sand to remove all the high spots on the frames and stringers.

Last but not least either side of the main keel; there are supporting timbers.   The reason this is put in, is to give extra width to the keel for the planks to be glued too.  These two pieces of timber, which go from bow to stern, are yet again made up of 1/8 x ¼ Obechi timber clamped and glued – slightly proud of the bottom of the keel (so the reason for this is when you sand – and on your final sand – you sand this level with the keel and it will also be at an angle with the frames).    If you imagine the apex of a roof of a house – the top ridge tiles – and that will give an idea of what the shape should be like.
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #5 on: March 22, 2008, 08:59:07 PM »

On the actual framework itself there are two more pieces of timber to go in.   These are for supporting propeller shaft tubes and also rudder tubes and ‘P’ brackets.     These were made from 2 pieces of 1/8 ply – 9 ¼ inches long x ¾ inch wide.  There is an oval slot cut in these to accommodate the prop tube; the slot was cut to roughly 1 inch longer than required, and also slightly wider than the propeller tube; in our case the prop tube is 6mm diameter and the slot was cut at 8mm wide.   These two pieces were notched and then glued into the frames – and the whole assembly was yet again allowed to dry overnight.   The next stage in the build is the good bit.  :)

Once we have checked and double checked that everything is square, there are no stringers that haven’t been glued properly, there are no pieces that we have missed sanding and we are happy we can commence planking.

Normally, when I diagonally plank, I like to commence roughly in the centre of the hull.   I know a lot of people like to begin at the transom (stern) of the boat; but, like I say, I prefer to start at the middle.   The reason for this – is, as we work towards the ends of the vessel, we can determine how many planks are going to be required and adjust the width of the plank so we are not trying to fit a ‘tiny fiddly’ piece in at the very last plank.

Now, with a 45° setsquare, I clamped this onto the framework, so that one edge of the square is flush against the keel and is parallel with the keel; and the 45° angle runs out from the keel to the chine so that the angle faces the bow.   Across the stringers I marked in pencil a line – it’s a Datum line, which we work from.   I mark exactly the same line on the opposite side of the hull, and this is where we place our first plank.   Now, for the inner planking, on this particular model, I am using Obechi planks – 1 ½ mm thick x 8 mm wide.  The reason I picked Obechi is because it is an easy material to work with; it is fairly flexible; can be bent well with the aid of steaming/hot boiling water and it is also a very tough material.   I had considered trying out using Balsa wood for the inner planking; but, after a few trials on test pieces, I found I had a personal dislike for using Balsa as it is a little on the soft side so I opted to go and use the material Obechi which I have used on many occasions and its my preference.    I am sure everyone will have their own preferred material to work with for doing their own planking.

The glue I am going to use, it’s the bog standard EVOSTIK (water proof evo bond) and I commence by laying the first plank along my line, leaving a slight gap of about 0.5 mm from the centre of the keel.  I then cut the plank oversize at the chine by about 3-4mm.   Now, quick note here. If we were going to diagonal plank – single skin – here – we would have commenced our planking on the sides of the hull, this being – when we finished the side, we sand the planks flush with the chine stringer and then when we plank the bottom, the planks overlap the side planks covering up the side plank end grain.   

The bottom plank end grain would then be covered up by the running strake that runs around the outside of the hull at chine level.  Therefore, effectively, sealing all end grains – so less chance of water penetrating the plank.  Water always penetrates quickly through an end grain, so, opting for that method reduces the risks of this.

We are opting for double planking – where we put two layers of plank – one on top of the other.    The inner planking – it doesn’t really matter where you start (i.e. bottom or the side).   Now, as I say, I started on the bottom.   First plank goes along the pre-drawn guideline, while I glue and clamp that in place, I mark off, cut and glue the plank on the opposite side of the hull.

This gives the glue on the first plank chance to dry.   I then come back to my first plank; and sufficient clamps allowing  :) I glue one plank forward of the first plank I put on making sure it is butted up tightly to the first plank and one plank to the stern of my first plank – so, in actual fact, I now have three planks in all on this side of the hull.

I allow these to dry, by going back to the 2nd side and doing the same.   As you have noticed, we are not using nails or pins but just clamps alone.    It is a slow procedure, because, it is just normally two planks at a time.   It took me roughly 2 – 2 ½ days to plank the hull.  That was working roughly about 12 hours a day – with me dinner breaks and of course FORUM BREAKS.  :)

Once I had completed the bottom planking; we sand the planking flush with the side of the chine ensuring we maintain a sharp edge on the planking.   We then move on to repeat the procedure on the side of the hull, where the plank angle faces the bow – the side planking runs in the opposite direction from chine to deck stringer, but, they actually run towards the stern.   Yet again, we mark a 45° angle from the chine to the deck stringer, using our 45° set square & on this line we begin our planking.

As we work our way towards the stern and the bow and we can see we are within 8-9 planks of completing the side, what we can do, we can clamp on several planks without glue, to estimate the distance thus to ensure that the last plank to go on is at least half a plank width.   I find the last planks normally end up being put on – right on the corner where the transom meets the chine.    It is advisable to try and aim for at least half a plank width, rather than something like ¼ to 1/16 width of a plank.

The reason for this is, you glue and clamp this on, and, you will find (well I did) it’s the first piece to chip off when you catch it with a sanding block.   But, if it’s over half a plank wide it does have a greater gluing area.   The way you achieve this, is, by reducing the width of one or two planks as you work your way towards the transom and the bow.

Once we have completed planking our sides, obviously we do have to allow it to dry out GOOD AND PROPER and then we sand the edges of the planks so that they meet the bottom planking.  This corner on the chine must be kept square – TRY NOT TO ROUND THIS CORNER OFF on the planking but use a short wide-sanding block with small movements along the grain of your bottom planking; working from transom to bow.

The next stage is to sand out any imperfections/unevenness on the planking on the hull.   Also, you will find, on some of the photographs you will be able to see a photograph which runs down the centre of the keel.   I have done this deliberately to avoid an air gap between the planks and the bottom of the keel.   This gap is now filled in with car body filler along with any hollows in the planking.   The filling was sanded down smooth – but not too smooth as we need a ‘keying’ surface for our next layer of planks.   Once we are happy with our inner planking and we have no imperfections and it is nice and smooth. REMEMBER WE MUST BE SURE HERE – BECAUSE ANY IMPERFECTIONS NOW IN THE INNER PLANKING WILL BE TRANSFERRED STRAIGHT TO OUR OUTER PLANKING having less material to play with (thickness wise) on this particular model.
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #6 on: March 22, 2008, 09:03:08 PM »

We come to do our exterior planking – now; the initial idea of this build, was to try and keep it as close  as possible and my idea was to try and keep it as true as possible to ‘real life’ on the exterior.

On the actual real vessels it was planked with 4 inch wide x ¾ inch thick mahogany.  For my mahogany I used 0.5 mm thick x 3 mm wide strips.   The first plank to go on was in the centre of the hull on the side, set at 45° from the chine  At the end of the day, I had put 70 meters i.e. 35 meters of planking on each side.  Wow that is an awful lot of planks – near enough 8 days solid planking – side and bottom.   In total there was 170 meters of planking put on the hull.

The method I used was to apply first of all, gently pull the string of mahogany through my finger and thumb nail – so that the plank gently curled.  The glue was then applied on the back face of the mahogany strip and then this strip was placed into position on the hull and then pinned down with dress makers pins until dry.   The excess glue was wiped off with a damp sponge, but, not too wet so as to the soak the plank; this procedure was done until the complete hull was covered.

It was then allowed to completely dry.   Once it has stood there for about a day or so, I sanded the hull in the direction of the planking – with various grades of sand paper; working from medium grade sand paper down to a fine sand paper.  Any gaps were filled in with a mixture of dust from the mahogany planking and a little drop of PVA glue and also any prominent pinhole marks were filled in using the same method.  Once the planking and everything had been thoroughly dusted off, I moved on to the next stage in the build.

The next stage was to coat the hull with an Epoxy finishing resin (PACER Z-POXY finishing resin).

Pause for thought;  if we had built the hull and just used the single layer of diagonal planking – personally I would have followed this route – I would have coated the hull with a polyester resin and then, with a layer of tissue mat, following by two further coats of resin – with a final sand. 

This does have its advantages and also its disadvantages; with it being a ‘largish’ hull; we are basically only relying on the thickness of the planking plus a few stringers for the hull strength – as the polyester and matting mixed will give a percentage of strength, it will not withstand a sharp impact very well.    I cannot comment about – if we had replaced the tissue with the material that the ‘flyboys’ use; because to date I have never used that yet. but hey I do plan to use that material in a future build.

If we had used say, thin plywood for planking on a single plank, this would have given us a much stronger hull.  So, for those who are contemplating building a diagonal hull there are a couple of ‘pointers’ to think about.   In this particular build, where we have double diagonalled planked it; we have actually increased the strength numerous fold, because we are actually producing a form of a plywood where the grain in the planking run at 45° to one another and this produces an extremely tough hull.

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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #7 on: March 22, 2008, 09:05:55 PM »

...... couple more pictures for the planking process .....  :)
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #8 on: March 22, 2008, 09:10:08 PM »

To move back to coating our hull with epoxy – so basically the strength is already in our hull and all the epoxy will do, apart from bonding it all together, is produce a very water resistant barrier between the elements and the wood.   So, the instructions on the epoxy say – mix equal amounts – I moved the hull into the nice warm kitchen, covered everything up – where I was going to be working – with old towels etc., no matter how one protects something – one always manages to splash with paint or resin – at least I do  :) and, you can guarantee that it will be your better half who will find it – not you.

So with this finishing epoxy you do get two containers, each containing 6 fluid ounces – one of hardener and one of resin and what I did was – I acquired the little tumblers that you use for measuring out cough medicine etc., I used two of them.   I measured out 15 ml of hardener in one and 15 ml of resin in the other one.   I poured this into a cap top that you get from a spray can – mix thoroughly which gave me 30 ml of mix – it was a little bit too much (believe it or not) to cover the whole of the hull.  Bear in mind the hull is 40 inches long x 10 ½ wide…..it covered it amply leaving a little bit left.   This was set aside and allowed to dry for two hours and what surprised me was there was no smell whatsoever from this epoxy. 

Once the mixture had hardened off on the hull thoroughly, and I had left it overnight; I rubbed it back with coarse wet n dry and rubbed it nearly to the grain of the planking once again, removing all brush marks and ‘ripples’.

I also used various blocks of wood as sanding blocks along with the wet n dry.

I then washed the hull thoroughly and dried it in the airing cupboard for a couple of hours and then gave it another coat of epoxy resin.   This again, was allowed to dry overnight.  The procedure of applying the epoxy to the hull was repeated; and once again when this had dried – it was rubbed back with medium grade wet n dry – not forgetting to use the sanding blocks as well.

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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #9 on: March 22, 2008, 09:12:18 PM »

moulding a plank to shape.......with fingers....
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #10 on: March 22, 2008, 09:16:00 PM »

The final coating of epoxy resin was applied; and the hull was allowed to stand and harden for good 24 hours.  Then I gave it a final rub down with fine-very fine wet n dry.   It was thoroughly washed off with warm soapy water and rinsed and given to me son Andrew to spray for me.  The first two coats were Halfords grey primer undercoat and these once dry were lightly rubbed down.     Then, there were three top coats given of Halfords acrylic satin black paint.   This was thoroughly allowed to dry for a couple of days; and to be honest with you – as normal – IMPATIENCE GOT THE BETTER OF ME – and I gently removed it by cutting it from the building board.  :)
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #11 on: March 22, 2008, 09:18:18 PM »

Prior to cutting the hull from the building board, I had made a building stand for the hull to sit in.    On the building stand the support faces which come into contact with the hull, I had lined with a very soft sponge; this prevents the paint from being ‘chipped off’.   Once the hull was off the building board and into its building stand, examine all the inside for any large blobs of glue that may have dropped/amassed on the inside of the planking and remove them with a scalpel taking care not to damage the planking on the inside.

Then I gave the inside of the hull with polyester resin mixed just pure polyester resin and work it into the planking and into the frames; the reason I used polyester resin here rather that epoxy (on the inside of the hull) is because its cheaper and also its there mainly to protect against absorbing any water that does find its way into the hull (polyester resin does absorb water over a period of time) unless it is coated with either paint or another protective barrier over the top.

Once this polyester resin on the inside has dried, we can set about installing the hardware/running gear.  On this particular build, with it having three motors, I installed the centre prop shaft first.   The prop shafts I used on this model are bog standard off the shelf ones.  I cut the outer tube so that it just long enough to emerge from the bottom of the hull; as it would do in a real life size boat.

We make a ‘P’ bracket up – first of all.   We select several pieces of tubing, the smallest one fits over the propeller shaft – in my case 4mm diameter.   The next piece of tube fits over the first piece snuggly and the 3rd piece of tube fits over the top of those two pieces snuggly – so in actual fact we have made a small telescopic tube and these are all soldered in place to make a rigid body.   

I acquired 4mm nut and bolt, which fitted snuggly into the tube.  This in turn was to become a mandrel which held the brass tube snuggly and I fitted the whole assembly into an electric drill. 

With the aid of a file and emery paper I profiled the brass tube into a shell shape.  We made three of these shell shapes, i.e. one for each shaft; and, after we they had been completed, I cut the legs from 1mm thickness brass plate.  This was soldered on squarely to the shell shape, along its length.   This now forms the ‘P’ support bracket at the end of the shaft.
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #12 on: March 22, 2008, 09:21:36 PM »

We now assemble the ‘P’ support and the propeller shaft into the central location in the hull ensuring that it is square along the length running true with the keel and also at the correct angle.   We have already pre-cut the whole to take the ‘P’ bracket but we do not Araldite this in first, we Araldite the main propeller shaft in first.

Araldite is a thick 2-part Epoxy resin.

Once this has hardened, we then ensure that the propeller shaft can turn freely.  This in turn centralises the ‘P’ bracket at the end of the shaft, centralising it and making sure it is true with the shaft.
When we are happy with it, we then epoxy the ‘P’ bracket in place.   The centre shaft now is our reference shaft for the marking off the distance for our two outboard shafts. They must be parallel to the centre shaft and also at the same angle.

The same is procedure is what was done with the central shaft i.e. epoxy the outer tube in first, followed by the bracket at the end.

Normally, I personally move on to fit the motor beds next.  I think I have mentioned before, I made a jig up a while ago which replaces the coupling and, basically it is a solid coupling, this is located on the end of the propeller shaft inboard side and also locates on the motor spindle shaft. This gives a perfect alignment between the motor and shaft (sometimes)  :) then; the motor mount is set into the hull with wedge shaped pieces of timber and glue and when the glue has hardened on the motor mounts – the solid coupling is replaced with a flexible coupling – and a trial run of the motor and the shaft is then done.   This ensures that it is in line.

Once we have all three motors lined up and set in place; I normally run them in – hey this is a good time to drop the phone in on top of the motors when someone next calls you as happened to me.  :)

When we are happy that there are no tight spots in the propeller shafts etc., we can then move on to installing the rudders.

This is where the set up, in this particular model, becomes interesting;     on the original full sized vessel, all the propellers turned in the same direction.  (Left hand – as we stand at the back of the vessel – they would all turn anti-clockwise.)

When the real boat is turning, the coxswain and the engineer would use a combination of speeding up, or slowing down either of the outboard engines to assist in the turn.  The centre engine would be dropped down to low revs and therefore not to interfere with the turning thrusts of the propeller.  Along with this manoeuvering there would be assistance from the rudders.  Now, on our model, we do not have the facility (as yet) to reducing the centre motor’s speed through the mixer.   It runs at the speed that has been set by the throttle on your radio handset.

I am going to get a ‘tighter’ turning circle either to port or to starboard (possibly to port more than likely).  To compensate for this I have altered the linkages between the three rudders so that; when I turn to port the port rudder virtually blanks off the port propeller.   The centre rudder only blanks off half of the thrust of the centre propeller and the starboard rudder blanks off only a third of the starboards propeller thrust.   When I say ‘blank off’ it directs the thrust of the propellers.   This system works both on both port and starboard movement.

The other alteration I made – originally I produced three scale-sized rudders – these looked rather small – so…I increased the size by wrapping them in Plasticard and this should also add in the turning circle.   The rudders themselves are made up from brass bar 1/8 inch diameter – inserted into two plywood cheeks, which form the shape of the rudder.    The tiller arms are all manufactured from 1/16 of an inch brass; cut and shaped, along with the use of parts from a three-pinned plug.   The linkages between the arms are all plastic to prevent any electrical interference.   At this stage, I have tested all of the electrical fittings – I have had a trial fit of the Electronic speed controllers, along with the mixer unit – so far so good.

Now I am very happy with this set up and it works well.

I can move back on to the build of the hull; the hull itself is basically finished now – there is the deck to go on, which I am busy with now.  The superstructure to build along with the deck fittings, guns and so forth.   As this is turning out to be a slightly longer and more enjoyable build than I ever anticipated – I have decided to put this part of the build on first, followed by the rest of the build – which will tag along after this.  :)  :D

.....   I'LL BE BACK

aye
John e
bluebird





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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #13 on: March 23, 2008, 08:13:50 PM »

Hi there,

Here is a scribble to explain the method/possible method of constructing the cut-down prop shaft and the P bracket support - this is a method I have used several times, when we didnt have the facility of a lathe to manufacture the parts.

We commence by obtaining a 'shop purchased' prop shaft of the correct length that we require for our prop shaft.  We remove the prop shaft from the tube; mark off on our tube the required length for our new prop tube - and, then cut it at our mark.

I normally cut the tubes in half with a small modellers pipe cutter - this does give a nice clean cut.  I then remove all the burrs and dress the prop tube up.

The next stage is to remove the bush from our redundant piece of prop tube - what I normally use to remove the bush is a tube which fits pretty neatly inside our prop tube, or, I have used a discarded knitting needle (from the Mrs) and I tapped the bush out from the inside.

The next procedure is to warm up gently, normally on the cooker top, the end of the tube where the bush is going to fit.   Prior to doing this, I normally put the bush into the freezer compartment of the frige and I divvent mean a bush from the back garden  :)   so while the bush is being frozen and contracting, the tube is going to be expanded with the heat.   This makes it a lot easier to fit the bush back into our new section of tube.  Let it cool down naturally, out of harms way......... yes I have tried to pick the tubing up when its still been RED HOT and yes, it does bring tears to the eyes.

The next stage, as you will see by the drawing, is to make the support bracket - this is basically 3 pieces of tubing.    The inner tube must be the correct diameter to fit over your prop shaft and it must be not too tight of a fit, you must be able to spin the shaft in the tube.

Then, its a case of two pieces of tube which will fit over the tube over your first piece of tube.  These are all cut to length slightly longer than one another - inner tube being the longest and these are then soldered - just with normal soft solder  - then I make a mandrel up and shape as has been mentioned previously in this build - with a file and emery cloth and then I add the support leg.

I do hope this makes it a little clearer - and - I will add further scribbles as we go along - but, just as a side note - the rudder and rudder tubes are made up basically the same way as we make the P bracket up - and I will add a drawing to explain later on.

Now....just going back to fit the deck.

aye
john e
bluebird
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #14 on: March 26, 2008, 06:54:09 PM »

2nd part fitting the deck – now we have to sit and think about the deck and if we think about when we did the deck on the Cervia, although we used a light ply on the Cervia’s deck and this was to facilitate the bends in the deck – the one going from bow to stern (the rake) of the vessel and also the bend that goes across the deck from port to starboard (Camber) – Light ply easily took the shape we required, with the use of a lot of weight and a lot of cellotape sticking it down while the glue stuck;  now then, if we look back at our plan that we are building from and look at the side profile – we now know why she is called ‘the Whaleback’ because of the shape of the deck line.

Not only do we have the camber of the deck, but, also we have a hump and a hollow in the deck.   This is going to be difficult for us to form out of plywood in one single sheet.

One option is open to us  - using very thin plywood – say 1/16 inch thick – we could lay it across the deck in say 3-4 sections, to give us an area to call the deck and where the joints are in the plywood we could fill and smooth in.   We could put the plywood on in 4 pieces, 2 at the stern and 2 at the bow.

There are 1-2 options as a I say, to look at using plywood, however, along with the plywood we are going to have to put some sub-structure underneath – this would hold the shape.  This is because, relying on the frames to produce this deck shape, is not going to be enough.  We would get hollows between the frames.

So, knowing that we have to put some form of sub-structure underneath – and this is going to add extra time to our build – let us have another rethink.   How was the original boat decked i.e. what materials were used?   According to all information I have – she was double-diagonally planked with mahogany planks with a canvas membrane between the planking – the same as the hull bottom was constructed.   This sat on deck beams and deck frames of varying sizes; supported by laminated gussets and elbows; so, we can take this and we can construct deck beams similar to the ones of the real boat for our deck to be laid upon.

Also, we could double diagonally plank the deck – this would give us a more realistic and closer to true scale hull.

So, our first job then, after we have smoothed off and obtained the correct deck edge shape and size; our next stage is to re-enforce the frame tops which we did with 1/8 inch x ¼ inch Obechi strip; one piece clamped either side of the frame at deck level, slightly proud of the deck by about 1/16 inch.

This was done on all of the 8 frames, including the transom.

The transom only had one support timber put in and that was on the inside.   Once all the glue had hardened on the frames, we then sanded in the correct deck camber, using a flat sanding block; some 10 inches x 4 inches.   This sanding block is just a flat piece of plywood with coarse sand paper stuck on the one side and fine sand paper on the other side.   The reason it’s so wide and long – this prevents one from sanding ‘hollows’ into the work.   Sometimes though it can be awkward to use, but, once you get the knack of sanding with it, you can see the benefits.

Now we have completed sanding the camber; we can think about putting the longitudinal deck beams in first; the first thing we must do is mark a centre line down the centre of all of the frames so we can work from the centre line – out over to each side.

Mark off on the frames that are appropriate – all of the opening areas (in other words all of the areas that are going to give us access to the inside of the hull).

We then work around these openings inserting our longitudinal deck beams in.   These deck beams are notched into the support pieces that we put into the side of our frames.   I commenced at the stern, working to the bow, putting the longitudinals in.

Then, I commenced putting horizontal stiffening beams in (these are the beams that run from the deck edge to our longitudinal beams).   Then after I had finished putting these deck edge beams in, I marked off the main opening area for the cabin and wheelhouse.

Where this is marked out, we have to insert the combing strips; this is where we have to cut out the tops of several of our main frames.   This is a genuine case  - of marking out once, checking 5 times – then re-checking and then eventually cutting once you are 100% sure.   Then, after we have cut the frame tops out we insert our combing strips.    What I did then was set the hull to one side for a while to allow all the joints and glue to harden up.

Whilst it was in the process of hardening I double checked all of the hardware in the hull – the motors, couplings, rudders, rudder couplings and linkages etc., ran the motors once again and checked the steering servo.   The reason for this is once the deck is on; if something does go on with one or two items, it may be major surgery to get at the item to correct the fault.   So rather check now whilst I still have reasonable access to the hull the better.

The glue has hardened and we go back to our sanding block and very carefully level and blend in all of the deck joists with the camber of the deck and also, the whaleback shape.

It is always adviseable now (says he) to remove the dust out of the inside of the hull SAYS he again! Thinking oh can I get the vacuum nozzle in here.  :)

Okay what method are we going to use, plywood, or double diagonal.   I really like the idea of double diagonal.   It gives the best option to produce the lovely shape of this deck on this boat.   So, we are opting to double diagonally plank the deck – we aren’t going to put the calico membrane in though; we are going to use Obechi for the first layer of planks 1.5 mm thick x 8 mm wide.  This will give us a rapid build up of planking for our first layer and then we are going to plank using our friend the 3 mm x 0.5 mm thick mahogany planking.

Start the process – we commence at the centre of the deck; at an area between the bridge front and the bow – roughly half way between.  We draw a 45° line across the deck support beams; to the deck edge.  This is done both port and starboard and this is the line that we used for our first plank.

We then glue on our first plank, exactly the same way we glued our first plank on the hull and we use the same procedure.  Five planks forward of the first plank and five planks astern.   When we have 10 planks on, we swap over and do the other side.; so this is where I am up to now   O0
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #15 on: March 27, 2008, 08:41:35 PM »

.... and now the next set of pictures will show you how I have finished the first layer of deck planking and if you note, I have not sanded the edges of the deck - flush with the sides of the hull as yet.   Nor on the main superstructure opening.    I leave this until the top layer of planking is complete.

The reason being the top layer of planking only being 0.5 mm thick is prone to cracking and breaking off, if it is overhanging and unsupported.

After I had finished planking the first layer, I sanded the complete deck smooth with me large sanding block and 80 grit graphite paper.

So...all the planks are level now and we are ready to commence the 2nd stage.

First plank to be laid is what is known as the 'king plank' do not forget this planking will not be set into the king plank; it butts up hard against it at 45 degrees.    The first plank to go down at 45 degrees to this king plank must go in the opposite direction to the first set of planking; I commenced at the bow about midway, working towards the broadest part of the hull.   The reason I work towards the broadest part first, is, if we make a mistake - save the plank - because as we are working down the hull or towards the bow the planks become shorter and we can utilise the plank that we have cut short.

I use the same method of gluing on the back side of the plank and the glue I am using is Evo-Stik exterior grade, yet again.

The plank is laid down and then rolled with a piece of steel tubing, this removes all the air from underneath the plank and it makes sure the plank is in firm contact with the deck below.   

When I have finished the deck planking, I will be rubbing it down, going through fine grades of wet and dry and I will be sealing it with sand 'n sealer, mixed with cellulose thinners 50-50 for the first two coats.   This allows a good absorption into the plank of the sand 'n sealer.  So, judging by the time it took me to plank the hull bottom, hey, you might not hear from me for a couple of days  :D :D

aye
john e
bluebird
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #16 on: March 30, 2008, 08:47:41 PM »

... update

hi there all - finished the deck planking and sanded all the deck sides flush with the hull

then on one of the pics you will see I am gluing and applying the deck rubbing strake.

The next pic you will see I am fitting the chine spray strip, this one you will see - I am drilling & pinning it as well as gluing it.   The reason I pin it with small brass pins, is it is submerged in the water most of the time and this is the area which will take the brunt of most damage which will occur during the hull's life time/.   So its a case of 'belt and braces'.

The final pics are a view of the deck with 3 coats of sand n sealer on - she is ready for first coat of grey undercoat.  Shame to paint it., but hey its got to look authentic.    :)
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #17 on: April 04, 2008, 01:22:36 PM »

hi there one and all

Just a little quick update - I have been waiting for information - which I have now received via email. Some photographs of the wheelhouse of this vessel.  This is because the plans I am building from are not totally wrong, but, they are slightly 'misleading'.  The sickbay cabin which butts up to the wheelhouse is a slightly different shape; it becomes more radiused on the corners as it meets the wheelhouse.   The plans do not clearly show this - nor does the Airfix model - nor do the plans show the rear window shapes.

So I am putting a posting/picture on which shows you where I am now - and hey for some people see if you can spot me 'BRAND NEW CRISP AUSTRALIAN YA NAR  - 50 DOLLAR BILL'.  Aye John  :D :D :D :D :D :D {-) O0 :) ;)

Bluebird
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #18 on: April 20, 2008, 08:17:11 PM »

Hi all,

Long time since I posted, been busy - believe it or not  O0

What looked to be a straight forward cabin build - has turned out to be - shall we say SLIGHTLY COMPLICATED not trying for perfection, but, to try and achieve a reasonable representation of the exact shape of wheelhouse and sick bay cabin.

In the past, I have seen some very good models, marred with the incorrect wheelhouse windows and sick bay; so, I thought I would have a go and try and get it as close to the real thing as possible.  This is where the plans I am using, basically 'fell apart'.    The plans give you a front, top and side view of the wheelhouse, and sick bay; but that is it.   They give no sections through to help predict the radius of the sick bay sides or indeed the wheelhouse roof.  The sick bay cabin top itself has several radius' along its length; beginning with a small radius at the stern and then as it reaches the back of the wheelhouse, it has a considerably larger radius.   This is to aid the view for the coxswain out of the rear view windows; to help with this I purchased the Airfix kit and I also received several good photographs to help me along with this.   Sad to say though; the Airfix cabin roof is not exactly right - but nevertheless, it did give me an idea of what it should look like.

This is where the advantage of having good photographs -  courtesy of Christian (cdsc123) - then you know what the real life size boat looks like.

For the construction; I was really taken aback by the way Gribeauval built his lifeboat shelter using the florists foam - so this was my first path - to construct a 'dummy sick bay' out of the foam and to laminate over the top with mahogany strips - 4mm wide x 0.5mm thick - double diagonal construction and similar to the hull and deck.   However, either - me being too heavy handed or inpatient - I found when I was clamping the planks down, I was crushing the foam.   When I reduced the pressure and tried to spread the load by using packing pieces between the clamps and planks; I found it was creating hollows in the foam.  So, plan A went right into the bin - or should I say 'shelved' as I want to use this method in the future.

Plan B came out, and this was to construct 'dummy ribs' of the sick bay cabin; then longitudinally plank along the side and use a plywood top.  This was all sanded and faired in; and, then I diagonally planked over the top of this to form a composite material.

I then sanded and filled the diagonal planking in and, as you can see, it has had its first coating of undercoat.    The next stage in the build will be to put the portlights in the side of the cabin and also the hatches and mountings for the gun turrets.

So far so good....... O0
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #19 on: April 27, 2008, 10:11:39 AM »

good day all

Now that I am happy with the shape and profile of the sickbay cabin and the wheelhouse; now moving on to markoff the position of the side portlight (portholes).   Oval portlights.

After scaling up from the drawings that I have for the position of the side portlights, when marked on the actual sickbay they did not look to be in the correct position i.e. too low down towards the deck.  So, back to the photographs and checking and double checking; and, one of the items on the photographs I used to guage the height is the air intake which looks similar to a question mark at the side of the cabin. 

I know this is in the region of just over 24 inches high; and, if we look, it just comes slightly above the bottom of the portlights.   So, I redrew the height for all the portlights from deck level.   Next procedure was to open them up, using a drill, scalpel, plus file.  Taking care not to break the mahogany outer veneer.   The next stage was to cut 14mm outside diameter plastic tubing - into segments of 5mm lengths.  These were firstly squashed between the fingers and inserted into the cabin sides; at the back of these I made up a Plasticard flange and I then glued the back inserts of the Plasticard flange to the inside of the cabin wall along with the window insert.

When all the glue had dried on all of the inserts, I then sanded all the inserts flush with the cabin sides and filled them where necessary with P38 car body filler.

The next stage in this process will be to manufacture another insert which will fit inside the portlight oval, to hold the glazing.   However, I have not done this as yet, I will leave this bit until I have finished painting the exterior of the cabin.

The next bit is to move on and mark off all of the cabin openings - the three hatches which are the engine room hatch at the stern of the cabin; the oval hatch in the centre which is in fact an escape hatch; plus, the sick bay doors.  These, when cut out will open into two segments.

You will also note that there are the positions for the two turretts marked out, and , these will be cut out after I have finished cutting out the sickbay doors.   

On the two openings which I have opened up, I have edged with a combing strip - of 4mm wide x 1/2 mm thick Plasticard.   This will become the flange lip.

So....more to follow.......
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #20 on: April 29, 2008, 02:55:49 PM »

 O0
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #21 on: April 29, 2008, 02:59:32 PM »

Hi all, there is supposed to be some text above the photographs I have just posted.   However, it is not allowing me to post.

see if this works

its in Martin's hands
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #22 on: April 29, 2008, 03:41:19 PM »


Well it seems the forum software doesn't like the words....... " I   c u r l " ( without the spaces' ).  :D

John please try posting again, inserting spaces in the word "Curl" in the 2nd paragraph.

... another word you can't post on the forum is "L y n x" ?!?!?! :-\

Martin
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #23 on: April 29, 2008, 05:39:32 PM »

Hi all with reference to my pictures above -  O0 :) -

Next stage in the build; is to construct the two sickbay folding doors - these are up-and-over doors.  I had already marked out the position on the side of the cabin to where the doors were to be cut out and to aid cutting a straight line; I glued on 4 pieces of copper wire in the position where the doors were going to be cut; I cut between the 4 pieces of copper wire with a scalpel first and then finished off using a very fine blade saw; the copper wire served two purposes a) it gives you a guide for a straight cut with your scalpel and saw and b) it prevents the outer layer of planking/veneer from splitting and peeling off.

So, once the door was removed from the cabin; the edges of the openings were sanded flat and smooth with fine sandpaper, along with the door edges.   The edging was then lined with 1/64 plywood to cover the end grain of the material up.   

Then the next stage; the doors are now going to be functional - in other words opening and closing because behind them this is where I propose putting the speaker for the sound unit (in this vicinity).

You may be able to purchase small hinges; but, I wanted to construct hinges 8mm long x 4mm wide.  It is, believe it or not, fairly simple to construct hinges.   Patience is all you need - no special tools - first what did I use - the hinges were constructed out of 0.5 mm x 4mm strip brass.  The tools I required 0.6 mm drill - a pair of flat nosed pliers - a pair of side cutters and two flat Swiss files/needle files.  First stage, have a look at the scribble of mine below.  First operation if you look at drawings 1 and 2, you will see that I bend the brass with the flat nosed pliers into a 'U' shape.  Into this 'U' shape I place the shank of a 0.6 mm diameter drill and form the rest of the brass around in a circle around the drill.   This gives us a nice tight loop.   Now, if you wish, you could run a bead of solder along the joint to make it really secure and this is entirely up to you, but, when you think about it - the hinges are not being opened up 24 hours a day (like a house door)  :) .

Anyway, we remove the drill from our loop and then we file a slot in the centre.  Our hinges 0.4mm wide so I filed the 0.2mm slot in the centre with the Swiss file/needle file.   The next stage is to make the 'tongue' part of the hinge.  We repeat the process of 1a and 2b in the drawing.  Where we come to process 3c - we do not file the slot - but, we file the 2 shoulders leaving the 'tongue' in the middle and it should be roughly 0.2mm wide. 

As you can see, this mates with the first part we made.   Before I join the hinges; I drill the holes using a 0.6 mm drill that I used to form the loop.  Cut the hinges off to length with the side cutters and snip the corners off - and, with the Swiss file remove all burrs and sharp edges.  It is then a simple operation of joining the two hinges together with a copper pin made from some wire.

The copper pin has the ends crimped to stop them from being 'pulled out'.    Once I hade made the 4 hinges, I set them onto the sick bay doors and as well as gluing them on into position with superglue - I used brass building pins as well, through the holes I had drilled in the hinges to secure the hinges further.   Once the glue has dried, I trimmed the ends of the pins off inside the cabin.

The next stage, is going to be, putting a lip on the inside of the cabin to prevent the doors from being pushed in over.

aye
john
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Re: 63 FOOT RAF AIR SEA RESCUE LAUNCH by Bluebird
« Reply #24 on: May 14, 2008, 11:43:15 AM »

Welll hello there one and all

No....I aint emigrated .... been busy  :D :D O0

As well as having a slight problem with me right arm, where I have had to wear a heated pad across the top of me shoulder.   To cut a long story short and to get on with the build, the heated pad you heat in the Microwave for 2 minutes ... and then obviously place upon yourself and allow the heat to penetrate the painful area.    Mind, you, me being a modeller and a 'try a different method' and of course trying to do more jobs than once - e.g. watch the telly  O0 {-) - I placed the heated pad to be 'heated up' on what I thought was 2 minutes on High power - turned out to be 20 minutes on TURBO HEAT POWER  :embarrassed: AS YOU can all imagine, we had not only a smell right through the house (worse than resin going off) but also a small fire inside the microwave - enough said......

back to the build  {-)

Right, we have come to the part of the build which is one of the most difficult areas to try and reproduce faithfully.  It is the perspex gun turrets.   With me using an 'oddball' scale 5/8 = 1 foot - you cannot purchase these off the shelf.  So, the alternatives are, try to find a clear top of some description off deodorant or something similar to the correct profile which from the last time I built these turrets are extremely difficult to locate.

If we have a look at the actual drawings, we will see that it shows two different shapes of ball turret.  On the first one it says the early turrets were, shall we say, a wasted shape where the base was smaller diameter than the middle section.   Think of a shape of a household lightbulb.   Then, on the rear gun turrets it shows a gun shaped turret, stating this was a later profile shape of the turret.   

Now, after scanning many pictures of the vessel + one or two films - I personally, could not locate a turret that was dome shaped.   So, this difference in turrets is (in my eyes) open to be questioned so I opted to build the earlier shaped turrets and this is the procedure that I adopted.  Sadly you do, well I wont say do, but I will say it is easier if you have the facility of a lathe.   First of all I produced a blank ball turret from 5 pieces of timber all clamped together, but not glued, with 2 circlips holding them, whilst machined.

This was sanded and polished, along with this, I produced two plywood moulding jigs.  Basically, 2 pieces of scrap-flat plywood 1/2 inch thick with 2 holes drilled in.   One hole 1mm larger than the overall diameter of the ball turret - 50mm diameter.   The 2nd hole was 54mm diameter.   These 2 pieces of wood were clamped together, so that the holes lined up.

The first procedure then was to manufacture 2 perspex domes.   Basically I cut 2 square pieces of clear PVC 80mm square, and 1 of these pieces was placed over the small hole in the plywood.  The 2nd piece of plywood was clamped over the top making the two holes were in alignment.  This was placed in the OVEN .... not the microwave :D :D :o ::) and the oven was set a full temperature until the PVC was soft enough for us to press our ball turret jig (as mentioned above) through the hole in the plywood thus producing a dome shape/bubble.  This was removed from the oven and allowed to cool.   I did have one or two attemps  >:(  anyway, I manufactured 2 domes in this manner, ACTUALLY FIVE - 3 scrap  :'(

Now, the next procedure is we trim off the base of the PVC leaving us with a nice dome shape.  Removing the dome plug from the inner of it.

Then, what I did next, was on the dome jig - as we will call it, I manufactured the cage from Plasticard strips - using Slater's MEK plastic weld to glue it all in place.   Once the cage was complete, I collapsed the dome jig on the inside, allowing me to remove it (don't forget the base is smaller than the top).   I then inserted the PVC dome which I had made inside the cage, this is at the point where I am at - at this present time now.    I am busy using a small amount of superglue to adhere the plastic strip to the PVC dome.  There is then just the moveable shuttering to manufacture - and this goes up and down with the guns and also, I have the guns and gun cradles to manufacture.

Aye
John e - bluebird
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