It's been a while since my last post on this blog. The really cold weather in December put me off spending time in the workshop and then Christmas arrived!

The endoscope I was waiting for arrived before Christmas. Its very small and works well considering the cost of less than £10.

I found some ribbon in SWMBO's sewing box. The label says "3yds 9d". Based on that, I guess it was bought in Leeds market sometime in the late 1960's by my mother-in-law. She could never have imagined it would get used for a kayak ! , but I'm sure she would be pleased to know it came in useful eventually 😂🤣

I made some long reach tools to help positioning the ribbon and to apply the epoxy along the inside seam. I found I couldn't use the endoscope at the same time as using the tools inside the kayak, but it did prove useful to check at intervals that the ribbon was in the right position. A length of ribbon was fixed along the inside seam on both sides of the hull. It wasn't an easy task, but I got there in the end.

Strips of ash veneer were laminated in position on both the stem and stern. Once the glue was dry they were sanded to a smooth shape.

Lightweight glass fibre cloth was applied to the stem and stern and sealed with epoxy. Lengths of glass fibre were also applied over the hull to deck joint along both sides of the kayak. Again sealed in place with epoxy resin.

My plan was simply to tape the two halves together and then run a length of fabric ribbon coated with epoxy resin along the inner seam. If only it were that simple!

The first problem was that the hull sides had curved inwards such that they no longer line up with the edge of the deck. I assume this is a result of coating the inside of the hull with epoxy resin.

To overcome this, several props were cut and wedged in place to spread the hull sides back to the correct width. Those props which would be unreachable once the deck was in place had lengths of string attached so that they could be pulled out once the two halves were glued together (assuming of course that the props weren't also inadvertently glued in position.)

The second problem was that it isn't possible to see much inside the hull with the two halves taped together. This was going to make positioning the epoxy soaked tape along the joint seam difficult. I thought about a mirror on a stick to help see inside the hull, but then found I could buy an endoscope to to use with a smartphone or a laptop, for less than £7! This was duly ordered and then became stuck in the post with the current UK postal strikes.

While waiting for the delayed post, I taped the two halves together with glass reinforced tape. Wanting to avoid gluing the temporary props in position while trying to place the epoxy soaked tape along the inner seam, I ran CA glue into the seam from the outside along both sides of the hull. Once the CA was fully dried, the props were removed and I was relieved to find that the joint held.

Now waiting for the Royal Mail delivery ......

One last thing to sort before gluing the deck and hull together are the fittings to hold the hatch in place.

Two elastic straps running across the top of the hatch will hold it down and I hope they will apply enough pressure to seal the neoprene gasket which will be in place between the hatch and the hull.

Brackets are needed to attach the straps to the hull. These were cut from a sheet of 0.8mm brass. A piece of masking tape was stuck on the brass sheet and the bracket outlines marked out on this. The holes were drilled and filed to shape before cutting the brackets from the sheet and bending them to shape.

Using black elastic for the straps, I didn't want the brackets to be bright, shiny brass so they were blackened by placing in a sealed container with a piece of kitchen roll dampened with ammonia. It only took an hour to take the shine off them 👍

Holes were drilled in the deck for the bracket fixing screws and M2 captive 'nuts' were made and attached to the underside of the deck. By having the nuts linked together in pairs, there is no chance of the nuts becoming loose and rotating when screwing the brackets in place. Based on experience, this is really important as the nuts will be difficult to access once the hull is assembled.

Finally, two channels were ground into the edge of the hatch opening on the deck to allow any water that does get splashed onto the hatch to drain away rather than collecting around the edge of the hatch opening.

I like to be able to turn the power on/off my models at the lakeside without having to remove hatches etc. I want a solution that is easy to operate and reliable, as there are so many other things to remember when preparing to launch. My two sailboats, the WeeNip and the Racing Sparrow have waterproof switches on the deck but this approach doesn't look right on a scale model. The power switches on my Crash Tender are fitted below the cabin hatch which slides over them to conceal them - if I remember 🤔. The Rowing boat and the Pilot Cutter have a pair of reed switches mounted below deck wired to a latching relay. A magnet is used to turn the power on and off by bringing it close to the appropriate switch above deck. One reed switch mounted on the port side turns the power on (P for Port and Power) and the other reed switch, mounted on the starboard side turns the power off (S for Starboard and Stop). This is the solution I'm going to use for the kayak.

The circuit diagram shows how it is all wired up. The latching relay has two coils. Each coil is connected to one of the reed switches. When a magnet is brought close to the 'ON' reed switch it activates one of the coils in the relay operating the contacts and turning the power on. The relay maintains this position even when the magnet is removed and the coil is powered off. Bringing the magnet close to the 'OFF' reed switch activates the other relay coil operating the contacts and turning the power off. Hence the relay only consumes power while changing state from on -> off or off -> on. It does not consume any power while the model is operating (or switched off).

A wiring harness was constructed on the bench having measured the required length of each of the connections. A charging socket is incorporated in the harness to allow the battery to be charged in situ. This socket will be accessible through the rear hatch.

The final three photos show the complete installation, prior to permanent fixing of the deck. It is possible to install and remove everything through the cockpit and the rear hatch.

Having a rudder is optional on a full size kayak, but I think it is going to prove essential on the model if there is to be any chance of it travelling in a straight(ish) line.

Drawings of a typical rudder were copied from Nick Schade's book, scaled and glued to wooden blanks. The blade is cut from western red cedar, the other parts from birch ply. The parts were cut out, cleaned up and brass tubes fitted to each of the pivot holes to act as bearings. A brass fitting was made to mount the rudder on the stern of the kayak.

To route the control lines from the rudder to the below deck servo two aluminium tubes were bent and glued to the underside of the rear deck with their aft ends protruding through the deck. These ends were then trimmed flush with the deck. The inboard ends of the tubes were flared.

Two cords will run from either side of the rudder, through the tubes and then to either side of the servo arm. The cords will be tensioned with either elastic or springs. I prefer the idea of using springs as they won't perish over time.

Final assembly will not be done until the deck has been attached to the hull, but I needed to get the aluminium tubes in place before then.

In addition to the rowing mechanism, I need to install the battery, receiver, paddling electronics and rudder servo.

For the battery, I decided to use 5 NiMh cells rated at 3300mAh. The decision was based on several factors.
1. Experience with the rowing boat where I've used 4 cells rated at 3700mAh. The rowing boat had 9 servos plus a 'transistor radio' and a smoke generator for Ben's pipe. The battery typically gives an hour or so rowing time, more if Ben doesn't light his pipe!🤣. The kayak has 3 servos plus the drive motor (a modified servo) so the selected battery should give plenty of duration.
2. The kayak needs some ballast and I prefer to use larger cells for this, rather than having to add dead weight.
3. The selected cells will fit under the paddler (just!)

The position of the battery under the paddler brings the centre of gravity of the kayak to a position just behind the location of the paddle which I think is where it should be. I may need to add some more ballast to balance everything up once the build is complete.

The receiver and paddle electronics are fitted into a plastic box (shown without it's lid) which sits just behind the paddler and battery.

The rudder servo is mounted behind the receiver. Both the receiver and the servo can be accessed through the rear hatch.

If you look carefully at the differences between photos 4 and 5 you will notice one of my 'mistakes'. Having glued the servo mount in the position shown in photo 4, I realized that I couldn't access the rear fixing screw through the hatch opening. The mount was carefully cut free and repositioned as shown in photo 5. Glad I spotted the issue at this stage rather than later.

As the cockpit opening is filled with the mechanism and the paddler there isn't much access available for anything else, so I decided to add a hatch behind the cockpit to give access to the rudder servo and the radio gear. It is not unusual to have a hatch in this location on full sized kayaks.

A paper template was drawn up on the computer, printed and taped to the deck. A scalpel was then used to cut around the hatch outline. It took a while, but eventually the hatch came away in one piece.

The template was rescaled on the computer to produce two more templates for a plywood rim to be fitted to the opening. The rims were cut from 1.5mm ply and glued into position.

The hatch will sit flush in the opening. It will eventually be fitted with a neoprene gasket and held in place with elastic straps. The double plywood rim creates space for the gasket while keeping the hatch cover flush with the deck.

Before the hull and deck can be permanently joined together, the mountings for the paddling mechanism need to be installed in the hull. Checks also need to be made to make sure that, once the kayak is completed, it will be possible to install the mechanism through the cockpit opening.

The mechanism was developed and tested while mounted in a cardboard mock-up of the kayak. Now, cardboard supports were cut to position the mechanism in the hull in the correct longitudinal position, and at the right height. Once everything looked to be OK the cardboard supports were used as templates to cut the final shapes from 3mm ply. These were then tacked into position with superglue and the mechanism installed for a final check with the deck in place.

It soon became clear that it was not going to be possible to install the mechanism in one piece, through the cockpit opening. This was not entirely unexpected based on the experience with the cardboard mock-up. The mechanism baseplate was cut in two, separating the paddler from the remainder of the mechanism. The two pieces are held in position with M4 dome head screws which fasten into a tapped brass plate glued underneath the plywood support rail. There is only one linkage between the paddler and the mechanism which will be straightforward to attach through the cockpit opening.

The cockpit needs a coaming adding to strengthen the opening and to give something for the spray skirt to attach to.

The coaming is built from lots of short cedar planks cut from offcuts of the strips used to cover the hull. These were glued all around the edge of the cockpit with CA glue. With all the strips in place and smoothed off, the deck was masked and a layer of glassfibre and epoxy resin applied around the outside.

Once the resin had hardened a layer of masking tape was applied over the resin and several strips of veneer were clamped around the coaming to form a lip. CA glue was applied to the top edge of the veneer layers and allowed to soak in. Once set, the lip was removed and cleaned up/sanded to a reasonable shape before being glued back onto the coaming using temporary spacers from the deck to ensure an even height.

The vertical strips forming the coaming were then trimmed down to the top edge of the lip and another layer of fibreglass and epoxy resin applied covering the whole coaming inside and out.

Finally the deck was removed from the formwork and the underside was coated with fibreglass and epoxy resin.

While the epoxy on the hull was left to harden, the deck was reattached to the formwork with hot glue. This is to ensure that the lightweight (flimsy!) deck is held in the correct shape. A layer of lightweight fiberglass with the weave running at 45 degrees was then draped over the deck and epoxy resin applied.

Progress is slow and frustrating with having to wait for the epoxy to harden at each step.