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.

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.

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 ......

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.

Having joined the two halves of the hull together, it was time to apply a coat of epoxy resin before finishing with yacht varnish.

Epoxy was applied to the bottom of the hull, left to dry and then a coat was applied to the deck. This is when the trouble started! The epoxy on the deck would not dry. It was cold in the workshop, probably too cold, so I brought the hull indoors and placed it by a radiator for a few days. This helped a little as the hull didn't feel quite so tacky. I then tried sanding the epoxy smooth. I tried dry sanding, I tried wet sanding, but it just wouldn't sand. The underside of the hull was OK, but the deck was just a sticky mess. I considered consigning the whole thing to my wood burning stove in the workshop - seriously!! At least I would be warm for a few minutes.

In the end, I scraped all the sticky epoxy mess off the deck using a piece of hacksaw blade. I then removed the remaining tackyness with a solvent (MEK). Fortunately, the underlying epoxy coating, applied before the two halves of the hull were joined, was sound. I don't know why the top coat failed to set. Was it temperature? Was the hardener past its use by date?

All the sanding and messing about left the hull with a white appearance which detracted from the appearance of the cedar timber so I applied a thin coat of french polish to restore the colour before applying 6 coats of yacht varnish. The end result, while not what I had hoped for, is not too bad, and at least I didn't burn it - I was so close to doing that..... now I'm glad I didn't. Onwards and upwards.

With the hull completed, time to make a stand that can be used for storage in the 'boat shed' as well as for transport to the lakeside.

A pencil sketch of the required cross section was drawn and copied. The copies were then glued to 9mm ply and cut out using the bandsaw. Each plywood piece had two 9mm holes drilled for supporting cross dowels.

I wanted to incorporate storage into the stand, primarily for the paddle, which will be removable for transport and a few tools. A simple tray formed from plywood strips was the easiest way to do this. With all the pieces cut, the stand was assembled using glue and panel pins. A bit tricky to assemble with only two hands, but once complete, the assembled stand is strong and lightweight.

A couple of coats of "quick drying woodstain" provides protection from water at the lakeside, and covers up the mixture of different plywood offcuts that were used in it's construction. A simple lid for the storage tray is attached with cord 'hinges'. A couple of magnets hold the lid closed.

Webbing straps loop over the ends of the dowels to form a carrying handle. The straps will also be used at the lakeside to launch the kayak. (The same straps are used with a similar stand for Scullduggery, the Bill & Ben rowing boat)

I'm concerned about the risk of the kayak sinking. It will be very low on the water and being long and narrow, it likely won't have a lot of lateral stability. Also, because of the mechanical connections to the paddle, even with a spray deck in place, it won't be possible to fully seal the cockpit against water ingress.

To reduce the risk, I decided to fill the empty space in the hull with polystyrene beads. The red lines on the first picture show the areas to be filled. I hope this will ensure that even with a capsize, the hull will remain afloat and not disappear to the bottom of the lake.

The hull was hung on a cord from the workshop roof and polystyrene beads were poured in to almost fill the spare space. To hold the beads in place, a handful of beads were coated with (waterproof) PVA and added to the top of the fill. Once dry, these formed a plug to hold the loose polystyrene in place. It will be a simple matter to dig out the plug and pour out the loose fill if it ever proves necessary.

The process was repeated to fill the other end of the hull.

Once everything was dry, it was time for a first float test in the domestic test tank. The mechanism, the RC gear, battery and the paddler were installed. It was a great relief to find that the kayak floated level, is reasonably stable and is self righting when tipped from side to side.

All up weight is just 1kg.

The hatch fittings that were made a few weeks ago screw into place either side of the hatch opening. Black 'knicker elastic' is threaded through the fittings to hold the hatch in place.

A neoprene gasket was made and glued to the underside of the hatch lid, together with a wire loop. A cord from this loop is attached inside the hull to ensure that the lid is never lost. Making a replacement to match the existing planking would be very difficult.

I was fortunate to find some miniature plastic buckle clips to fasten the elastic over the completed hatch.

The rudder mounting pivot was attached to the stern of the kayak using brass pins and epoxy. The rudder itself was then fitted using a length of M2 threaded rod as a pivot. As with a full sized kayak, a length of bungee cord holds the blade vertical but allows the rudder blade to tilt backwards if it comes into contact with something underwater.

The rudder is linked to the servo using two cords which run from the servo, under the deck through the previously installed aluminium tubes and then exit through the deck adjacent to the rudder. The small springs provide some tension in the cords to remove any slack and backlash.

An additional line runs from just behind the cockpit, through small guides glued to the deck, and attaches to the top of the rudder blade. On a full sized craft, this allows the kayaker to raise the rudder blade to avoid obstructions.

The short video shows the rudder in operation:

With everything finished, it's just a matter of installing it all into the hull.😉

A temporary paddle was made for initial trials on the water. There are many variables to be settled for the paddle in terms of paddle length, blade size and the feathering angle between the blades. Once these are established, then a 'fancy' paddle will be made.

Pictures 3 & 4 are from an earlier post and show everything in situ, before the deck was added to the hull.

With the deck in place, it is difficult to see very much. It is also difficult to install all the bits, but with a little patience, it all fits.

Manufacture of a spray deck from rip stop nylon was subcontracted to my wife, who has much more patience than I do.😇 An elastic cord run inside a seam around the edge grips over the cockpit rim.

With everything in place, a short video to show the action: