The final bit of the glassfibre and resin stage was to apply some 50 gsm cloth to the deck, again with the Z-Poxy Finishing Resin. The whole deck surface was covered and then rubbed down to receive a second coat of resin. This deck area will later be finished with a textured coating to simulate the anti-slip surface that is usually found on service boats such as this so it’s not essential for me to finish the epoxy to a fine surface.

The rubbing strakes around the hull at deck level were tackled next and I chose to fit a 10mm wide strake rather than the one supplied in the kit. This is so that I can later fit a 10mm wide half round neoprene ‘D’ profile ‘bumper’ around the deck. The Obeche hardwood strip I used had to be ‘heat bent’ to roughly the correct curvature of the bow and I also put some relief cuts with a razor saw so that the strake could also be formed in a second plane, a somewhat torturous process for the wood to get it to conform to the bow shape particularly as I wanted the strake to be mostly vertical around the hull so that the ‘D’ profile rubber looked correct.
To achieve this I also had to fit some small spacer pieces at the bow to push the bottom edge of the strake away from the hull. The first strake was glued and pinned in place and when set the other side was fitted with an overlap at the tip of the bow which will be later ‘rounded’ so that the rubber strip goes around it smoothly. All the gaps at the bow were filled with a two part wood filler after the overlap was cut off.

The chine strakes are also Obeche hardwood strips that needed some razor saw cuts at the bow and they were both fixed with epoxy resin glue and holding pins. The instructions are a bit vague on where they should finish on the bow keel so I had to judge this by eye with reference to the ‘photos in the instructions. I didn’t shape these strakes before fitting because it would be easier to put a small chamfer on the upper edge and shape the bow and stern ends after they were fitted.

The strakes on the underside of the hull act as lifting strakes to help the hull rise when planning at speed, the instructions say that the supplied 5mm square Obeche strips should be sanded to a half round profile before fitting but I decided to make them to the true shape of a lift strake by machining them to a triangular profile. This proved more difficult to achieve than I thought, my first attempt being to try to mill them using a jig and my Dremel with a milling bit. This was not too successful and I found it far easier to just lay the Obeche strip in the long groove of an off-cut of decking timber and planning it down along its length.

I was clearly over-thinking something that was not really a problem, and the simple solution was the best.🤓

When all the strips were prepared I laid them on the hull bottom at the required spacing and pencil marked the hull with some guide lines. A small amount of bending and some relief cuts were required on each before they were all glued in place with epoxy and when set the ends were trimmed and shaped.

The side rubbing strake 'lattice' pieces will need to be added before the hull gets its final coat(s) of epoxy finishing resin. 😁

I have decided to hold off from completing the superstructure for a while I consider constructing an alternative design of cabin. There is a particularly good example of a more authentic cabin structure on a Harbour Pilots Boat that operates in Southampton Water and Skydive130 is making the same SLEC kit as me and is altering the cabin design on his to mimic the Southampton boat and making a very decent job of it👍, so much so that I think I will be altering mine in the same way. So although my cabin was actually completed weeks ago I'll be scrapping it and starting again.😮

Meanwhile I can continue with my build by applying the glassfibre cloth and epoxy resin to the hull.😁
On all the boats I have built before I have done this to reinforce the hull and to provide a good surface for the paint finishes. The first stage is to give the entire hull a good sanding with a 180 grit paper and then brushing off all the dust followed by a thorough clean with some panel wipe to remove any residue of oil, grease or silicones that would react with the epoxy resin.
I used a 100gsm (grams per sq metre) woven twill cloth with a fast setting epoxy resin mix that has a 30 minute ‘pot life’ before the resin starts to become unworkable.

My preferred method is to apply a coat of resin over the hull and then gently lay the cloth into the resin and then lightly brushing from the centre of the cloth outwards without applying any additional resin, this ensures that the cloth settles into the resin and any creases or bumps are easily brushed out.

I applied the glassfibre cloth in five stages starting with one side of the bottom of the hull and when set continuing with the other four faces of the hull the last being the transom. This process usually takes a few days but the resulting cloth and resin surface is free from ripples and bubbles and I can then give the whole hull a light sanding to flatten the surfaces.

Previously I have used additional coats of the EasyComposites resin but on this occasion I used Z-Poxy Finishing Resin because the cure time is about four hours which means that I was able to apply a second coat of resin over the entire hull, again in five stages over the course of a single day. I have found the Z-Poxy finishing resin far less susceptible to producing streaks and ‘fish eye’ blemishes in the surface, but I still clean over the entire area with fast evaporating ‘panel wipe’ to remove any last traces of silicones or oils from my hands and fingers.

After leaving the resin to cure completely overnight I was able to sand the entire hull with a 480 grit ‘wet & dry’ abrasive paper used wet to flatten the epoxy to a fine finish.
The next stage will be to fit all of the rubbing, chine and lift strakes.

At this stage I can set the hull aside and continue work on the superstructure base which fits inside the deck aperture. If the base has been constructed properly it should fit inside the deck with a couple of millimetres clearance all round and be should be flush with the deck framework all around.
Two pieces of obeche strip were previously added to the insides of the deck aperture to support the framework at the front and rear making sure that the framework is still flush all round, if it’s not there might be a twist that needs to be corrected.
Fortunately my base was OK and so I just used my sanding plate on the base of the frame to take off any high spots.
The whole deck area was also sanded to remove any high spots too. Knowing that all was as it should be I glued and pinned the obeche strips in place. The 1.5mm ply inner deck skins were then glued and pinned to the framework all the while checking that the frame was still square. When the glue had set I trimmed the skins back to the frame leaving a very small overlap to allow for finer adjustment later after the deck skins have been added.

The deck skins were added next starting with the piece that covers the bow, but before fitting it I added some additional strips of obeche and balsa to add extra support to the bow skin, this is so that when I add deck fitting at a later stage they will be supported properly. Those extra bits were sanded to the correct curved profile of the deck using the sanding plate and the upper part of bulkhead B1 as a guide.

I fitted the skin at the bow first, followed by the rear deck. The deck side skins need some additional support strips of scrap obeche fitted in a couple of places before the skins were glued and pinned in place. After the glue had set I then trimmed all of the deck skins flush with the hull sides all round.

A small amount of trimming of all of the skins was required for the superstructure base to fit into the deck aperture and if all is well the skins should all be reasonably flush.

The cabin is assembled as a separate part that is fixed on top of the superstructure base. One of the cabin sides is laid flat and three cabin formers are fixed into it using the tabs and slots in all the parts and then the other side of the cabin former is attached.

This assembly was then glued and clamped together making sure that it was square and without any twist. Various additional formers were then added that form the engine room front face and other parts that form the cabin windscreen and rear door panel.

There appears to be another slight error in one of the windscreen formers that would prevent the windscreen panels sitting properly in the same plane so I re-made this part in new ply to make it to the correct angle, another item to bring SLEC’s attention to.

With the bottom skins firmly fixed in place and the glue set, all of the clamps and pins were removed and I was then able to trim them back to the lower chine using my small block plane and sanding plate paying particular attention to the area where the side skins overlap the bottom skins at bulkhead B1.

The application of the side skins is also quite straightforward and again I used my heat gun to pre-form the skins to the shape of the hull at the bow. It’s quite remarkable how well the heating a bending of the skins works and the process only takes a few minutes to achieve the correct curvatures. All of this means that the skins sit almost perfectly on the hull framework first time and really don’t need to be forced in place. Despite this advantage I still prefer to fix the skins down with pins and clamps as the aliphatic glue sets.

The side skins need to be trimmed back at the deck level and the chine and it’s very satisfying to see the hull taking shape. The side skins were blended into the bottom skins at bulkhead B1 and the excess overlaps of all skins carefully removed at B1 and K3 to allow for the fitting of the balsa blocks that form the lower part of the bow.

The supplied balsa blocks needed to be sanded back slightly on one face to fit properly into the recess formed by the main keel K1, bulkhead B1 and the formers K3 because those parts don’t form a true internal square but it’s easy to sand back one face of the blocks on my rotary sander. Before glueing in place the waste areas of the blocks were marked and removed with a razor saw. When set the medium hardness balsa blocks are very quickly and easily shaped with a block plane and sanding plate, and the whole of the bow area was then blended together into the bottom and side skins and the keel.

Moving to the other end of the hull, constructing the stern is the next stage described in the supplied instructions. This starts with the lamination of three balsa parts that form the upper part of the stern which are glued in place and then sanded back to the curvature of the rear deck. The transom former TS3 was then fitted between the keel and the balsa lamination.
Because I have sufficient overlap of the bottom skins I decided to fit the lower transom formers TS4 inside the skins, this involved just re-shaping them slightly to fit against the bottom skins and the bulkhead part B5. After the addition of two outer strips of obeche the whole area was then sanded back to the correct curved profile of the stern. This deviation from the supplied instructions means that the bottom skins are continuous to the stern and I think make for a stronger and neater finish. This is another thing that I may suggest to SLEC as a possible modification.

The inside faces of the stern cavity and the internal exposed areas of the stern skin were given a couple of coats of sanding sealer (but not over the glueing areas) as a precaution against any ingress of water affecting the wood as later on I will be piercing the stern to fit the ESC water cooling outlet tube.

Finally the stern skin ST5 was glued and pinned in place, as before this skin was heated and pre-formed with a heat gun and when the glues had set the skin was trimmed and sanded back flush to the side and bottom skins.

As with my other models I will be using glassfibre cloth and epoxy resin over the whole hull to add strength and to provide a good surface for the paint finishes. The hull still needs the addition of some bottom and side rubbing strakes once the fibre and epoxy stage is done.

Now that the chine and rubbing strakes are fitted to the bow and bulkheads I have a fairly rigid skeleton on which the skins will be supported. However before the skins go on there are some extra keel parts to fit and these are in the form of laminations that are fitted on either side of the keel. In two places there are two laminations on either side of the main keel piece that thicken and strengthen it to take the propshaft and rudder tubes, and these parts were laminated on the bench and given a slight chamfer with a plane so that the bottom skins fit flush and this is much easier to do before fitting.
There are three spacing tabs in the main keel where the propshaft tube goes, one of which needs to be cut out before the keel laminations are applied and the remaining two are cut away after the doubled-up keel parts are fitted. The rest of the keel laminations are single pieces per side and were also chamfered before fitting.

The strakes and bulkheads now need to be shaped to be as flat as possible and this is easily achieved with my trusty block plane on the stringers and then a final finishing with a ‘sanding plate’ over the stringers and bulkheads. The sanding plate is no more than a piece of MDF about 9” x 6” with an 80 grit abrasive glued on one side and 60 grit on the other and because it is large enough to bridge at least two points on the framework will always remove wood while maintaining a flat ‘plane’ which is essential for the skins to fit properly. At the bow the use of the sanding plate quickly blends the deck part K3 and the chine stringers, including the extra lamination that was fitted to correct a design error. Throughout the planing and sanding process the entire framework was checked flatness using a straight edge to check for any high spots, and because of the use of the sanding plate it’s difficult to introduce any low spots with the plate supported over two or three places.

The keel was then drilled to take the 8mm propshaft tube, fortunately I have a suitably long 8mm bit for this. A final finishing with a long round file was needed to neaten it up and provide a loose friction fit for the tube. I won’t epoxy the tube in place until I have all the parts of the drive train to hand to ensure that the alignment is as accurate as possible. The rudder position is pre-marked on the keel by a notch in the main keel but I’ll be leaving the drilling of the rudder fixing hole until the all the skins are fitted.

The bottom skins are fitted first and are quite accurately CNC cut and only require minimal trimming and chamfering where the skin meets the keel. I used my ‘heat Gun’ technique to put a permanent bend in the 1.5mm skins so that they conform quite closely to the curvatures at the bow and but some modelling pins and a few clamps are still needed to hold them in place when glued. The skins are fitted from bulkhead B1 to the stern with the bow section being formed from carved balsa blocks. When fitted correctly the bottom skins extend beyond the stern bulkhead B5 by a couple of centimetres and the instructions tell you to trim them back to B5 and then fit some extra parts to form the curved transom but I’m going to re-work this by taking advantage of the surplus bottom skin overlaps which I think is a much better solution.

It the time of writing (mid April) I’m still waiting for the rudder and motor coupling I have ordered from the UK supplier, and most frustratingly the motor, speed controller, battery and RC receiver are all out of stock with my usual supplier for these bits (HobbyKing’s UK warehouse is temporarily closed under the Covid-19 restrictions) with the hold-up most likely as a result of the shutdown of the Chinese factories that produce the majority of these items these days.

In the next part I’ll be fitting the side skins, shaping and fixing the balsa bow blocks and building the curved transom.

With the main framework of the keel and bulkheads assembled the next stage was to fit the stringers that run the length of the framework on each side.
The hull design is a ‘Hard Chine Deep V’ type that gives the real boat its speed and stability characteristics. The lower one is the Hard Chine and the upper one is the Rubbing Strake and these are formed by laminated strips of Obeche hardwood which are shaped to the contours of the hull by planning and sanding at a later stage.

Starting with the lower stringers that form the Hard Chine the notches in all of the bulkheads were filed to the correct angle to ensure that the strips fit properly and the first strip was glued in place and secured with modelling pins. Fortunately the Obeche strip is pliable enough to accommodate the bend at the bow after a little wetting and heating with a heat gun (electric paint stripper). This was repeated for the lower chine on the other side, all the while still checking that the framework was still square.

Fitting the upper Rubbing Strake is a similar operation with the bow ends requiring a bit more bending, but assisted by some cuts made with a razor saw, all the while checking the assembly for true and square.

The second laminations were then added to both chines on each side, pinned and clamped all along their lengths and while they were setting the two small keel parts K4 were roughly chamfered to an angle and fitted about 3mm back from the main keel at the bow.

At this point it became evident that there’s another small design error, in that the keel parts K2 need to be re-designed to extend further out to the bow so that the hull skins fit properly where they meet the main keel K1 and the two K4 parts. We saw previously that this part was already in need of modification in the first part of this build blog. So that’s another thing to let SLEC know about but again easily rectified by adding a short third lamination over the Hard Chine back as far as bulkhead B1 that can be sanded back to the correct size and shape.

This assembly was then set aside and work was started on the Superstructure Base which has an upward curve along its length that follows the contour of the deck. All the parts for this are laid out in. This ladder type framework needs to be assembled absolutely square and to assist this I fixed down some battens and ply off-cuts and the bench to form a jig to hold all the parts in place during assembly. The upward curve of the Superstructure Base makes this a bit tricky but with all the parts glued, pinned and clamped the piece was carefully checked for true and square and left to set.

When dry the piece was removed from the jig and, as per instructions, placed in the main hull assembly so that the ends were flush with the bulkheads B1 and B5A so that two strips of Obeche can be added, these locate and support the Superstructure Base at the front and back.
Some 1.5mm ply parts form the inner decking of the Superstructure Base and these are glued, pinned and clamped in place on the framework. At this point it’s vital to check that the assembly is still absolutely square or the base will not fit properly into the main structure.
I used my heat gun to set a slight curvature in the ply panels so that they sit on the frame correctly. The application of heat on the thin 1.5mm ply has the effect of temporarily softening the glue between the plies and relaxing the bond, and allowing the panel to cool while bent will set the bend into the ply. I’ve used this technique to shape the plywood skins on all of my model boats and it’s a much quicker and cleaner method than using steam.

The next part will cover the fitting of some additional keel parts, drilling the keel to take the propshaft and trimming the chines and strakes in preparation for fitting the hull skins.

It’s been a while since I built my last model boat, a Thames River Police Launch and prior to that my RAF Crash Rescue Tender and I thought I’d better get something on the go pretty soon or I’ll have nothing new to show at the club exhibition in September.

While I was visiting the Warwick International Model Boat Show in November last year I spotted a new model by SLEC of a Harbour Pilots Boat, due for release in Spring 2020.
A quick ‘phone call to them confirmed that it was now available and so I decided to buy the kit and start building it to keep me occupied during the enforced isolation we all find ourselves in at the present.

The kit arrived the following day, very safely packaged in a strong carton, and after opening the box and quickly checking the contents I took out the supplied Building Instruction and Picture Instruction manuals and studied them both at length to familiarise myself with the construction sequence.

Anyone that is familiar with the old Aerokits/Keil Kraft model boats will recognise their characteristic ‘egg crate’ method of construction and this model is a re-working of one such design by Ian Hull for SLEC.

Fortunately I have all the required tools, adhesives and other materials in the workshop including a 10” propshaft and 40mm 2 blade prop that I bought in error for a previous model and so I can make an immediate start. I’ll still need to buy in a receiver, servo, rudder, brushless motor and speed controller and a couple of LiPo batteries at some point but I certainly have all I need to make a start on the build.

All of the plywood parts are CNC router or laser cut and many of the parts lock firmly together with tabs and slots that are already quite a good fit, but however fine the router bit is it can’t produce a sharp 90 degree cut so the first thing the instructions tell you is that you should use a small square file or a sharp knife to square all the internal corner cuts to ensure a proper snug fit.

Construction starts with the assembly of the main keel, first bulkhead and the two small parts K2 that lock it together. At this point I’m dry-fitting the parts to ensure that it all slots together correctly. It’s here that a small improvement could be made by re-designing the two smaller parts so that the tabs that slot into the main keel K1 are staggered rather than meet at the same point as the existing slot is long enough. Easily fixed by amending the CNC files but for now it can be fixed by filing each tab to half its length, but I’ll pass on the suggestion to SLEC.

The remaining bulkheads are slotted onto the keel and the two long beams are slotted in at deck level to lock it all together.

When I was happy that all was well I took it apart and re-assembled it all using a waterproof aliphatic PVA glue and a few clamps to hold it all together while the glue sets. A try square was used to check the assembly for square.

In the next part I’ll be fitting the strakes and additional keel parts and constructing the base of the superstructure.