Monday 5 September 2011

Finishing the canoe hull

I strongly recommend applying at least one coat of un-thinned epoxy to all of the plywood surfaces inside and outside the canoe. The official advice is that you should pick your time of day carefully as you do not want rising temperatures to cause expanding air to bubble from the wood after you have applied the epoxy. I was very careful about this and ended up with a forest of bubbles despite a careful application and “tipping” out – so there may be more at play here than meets the eye. Not to worry, sanding is good exercise and the epoxy needed some sanding in any case to prepare the surface for the final finish.
When applying the epoxy coat I did take the time to ensure that all of the plank joints were completely filled with epoxy leaving no tiny gaps for dirt or anything else to lodge.
The plan for the interior, decks, inwales and outwales was simple – four coats of yacht varnish. A little care needed to avoid runs but nothing to learn. All anyone needs is a dust free environment, no wind and a dry atmosphere. OK – so lots of potential trauma there but hey nothing new.
The idea for the exterior was to apply a coloured catalytic polyester resin. This would provide a scratch resistant coloured finish – ideal for resisting launch and recovery damage as well as those small collisions that even the most expert paddler comes to expect from time to time – and happen to me all of the time. I am pretty sure that this material will become the finish of choice for canoe builders – if they can figure out how to apply it. Does that sound like I had problems? Well I did. Where it applied properly, the finish is smooth, glossy and looks great. Getting that smooth glossy finish involves getting a thickish layer smoothed out well before the hardener kicks in. “The tin” promised 20 minutes of “pot life” – my first attempt got less than 5 with everything turning to jelly at around the same time.
Experiment and bitter experience has shown the following. The resin will not adhere successfully to plywood that has not previously been treated with a coat of epoxy. If you rub down one layer of the material you can successfully bond a second layer to the first.  Applying too thin a layer may mean that the material will not harden successfully.  While it takes some rubbing down, a smooth final finish can be produced from even the most inauspicious start.
So that is why my final exterior finish is “Topcoat” applied to the number one plank and polyurethane paint in a matching colour applied to the rest.
Quick final round-up:
Sorry for the lack of pictures from the final stages. Things were done in fairly short order on flying visits home to France. Also this year saw the worst drought in SW France that anyone can remember and most river craft have had to be fitted with wheels. As you will not want to see my pride and joy floating on my neighbours very small swimming pool,  I will post some pics of my canoe being paddled after I next get afloat on one of the great French rivers.
You can buy great seat fitting kits that come with wooden dowels that can be cut to length  to cover the bolts once you have run a couple of trials to get the seat height right for you and your canoe. Using one of these kits will save a lot of time and trouble.
I did start reading a text on paddle making but when I realised it started with selecting a suitable tree, felling it, ripping out some planks and leaving them to mature for several years I reached for a canoe suppliers catalogue and found a good range of attractive wooden paddles at remarkably low prices.
As I am now living back in the UK and I have a large garage space (well more a potential space than an actual space you will understand – subject to family negotiation and prioritisation) then new projects beckon. Building paddled water craft may well be addictive as well as contagious, just as Paul said when I started this venture.

Tuesday 30 August 2011

Glassing the interior

The day following the glassing of the bottom exterior of the hull I turned the canoe over and prepared to glass the inside. First, I gave the inside a good vacuum cleaning to remove any wood dust or other detritus. Then I used the same plastic based masking tape as before to mask the edges of the number three planks. However we also need to create a fillet between the one and two planks and along the centre line of the keel to provide a smooth line for the cloth to follow. Glass cloth does not do sharp transitions. I used paper masking tape to mark the outside limits of the centre line fillet and to mark the limits of the fillets between the one and two planks. I aimed for quite narrow fillets in each case.
Next I laid the remaining roll of glass cloth in the bottom of the boat and trimmed it to the outer limits of the masking tape running along the number three planks. I then carefully removed the cloth and set it to one side.
I then mixed a batch of epoxy and added plenty of wood flour to get a nice, thick filler. I applied the filler to the prepared and masked joints using a soft plastic pallet knife purloined from the kitchen. Around the middle of the centre line of the keel the angle where the planks meet is pretty shallow but it is worth ensuring that sufficient filler is applied even here to get a contiguous fillet from end to end.  This job is best done with a sequence of small batches of thickened mix as the required quantity is a little difficult to decide in advance.
Once the fillets had been created I removed the masking tape strips – with the exception of those strips protecting the number three planks. I then carefully replaced the glass cloth back in the bottom of the boat – stretching it out but being careful to not disturb the still soft  fillets in the plank joints. Then it was back to the formula of mixing small batches of un-thickened epoxy and using these to wet out the cloth over the two sets of planks and the fillets. This is slightly more of a fiddle that when working the outside of the hull but the practice of the previous day keeps the process flowing. If all goes well, you will end up with a neatly glassed bottom with three attractive dark lines running fore and aft marking the joints between the planks. The glass cloth and the wetting out process nicely finishes the fillets although you should probably take care not to apply too much pressure as that might distort the lines.
In spare moments while waiting for the resin and glass cloth to cure sufficiently to allow the trimming and removal of the excess along with the masking tape I took the time to shape the back face of the seat doublers and to glue then into their intended locations on the inwales.
The decks:
A piece of advice for those who have followed this process from the beginning. Go back and do not cut out the decks from the ply sheets. Instead cut out two rectangles of plywood wider and longer than the provided deck lines. Why? Well the bulkhead fitting is a bit of a trial and error process where you strive to get them in place and to fair the lines of the unglued hull. This combined with a number of other factors means that while your canoe will hopefully have a pleasing sweep of lines they will probably vary a tad from the designer’s original drawing – and probably from his or her first build. If you take this advice then you can offer up your deck ‘blanks’ and draw around the lines of the outwale to get the exact shape and length for each deck. Cut the outer line of the deck the thickness of the outwales in from the marked line and then find a nice curve to act as a guide for the final curve above the bulkheads.
If you did cut out the decks to the designer’s lines (like I did) then you will find that you have to adjust the line  – and this will a bit more difficult if you can’t use the outwale curves to assist.
I cut my splashguards from some oak stock and glued them onto the decks  - once again demonstrating that I am much better at cutting convex than concave curves – but they do not look too bad and the colour contrast is nice.
Now the next piece of advice – something I wish I had thought of when gluing my decks in place, instead of a couple of days later. Shape and glue a strip of plywood to sit behind the bulkheads and to accurately meet the line of the deck when fitted. It might even make sense to shave a little off the bulkhead tops to give a clear gap between these edges and the deck line. If you are as ham fisted as me then this will save a rather bodged joint between the bulkhead and the deck after gluing. With the plywood piece in place, filling the joint would be simple and clean
I also took some time to make two simple seats from oak strips I ripped from some lengths left over from cutting the inwales and outwales. I also cut a section of mahogany to form a thwart – cutting a rough hourglass shape and then sitting in the sunshine to sand the curves until I was happy with the look and it felt good in my hands.
I varnished the seats and thwart using the “duffers” method. This differs from the manufacturer’s recommendation printed on the tin. I suspect that varnish manufacturers deliberately list a complex sequence of steps (including some specialised thinners) so they can be pretty sure that no-one ever follows them exactly – giving them an “out” when anything goes wrong.  My method involves applying three coats of un-thinned varnish; allowing the minimum recommended elapsed time between coats. I then rub down any roughness caused by raised wood fibres still pushing through the varnish surface with very fine wet and dry paper and then apply a fourth coat. Job done,  with a nice deep glossy finish every time.

Friday 26 August 2011

That canoe project (Mike Griffiths)

After fitting the inwales and outwales I took the time to give the canoe hull an initial rub down. I concentrated on where I had filled the wire holes and on any marks left by the wires on the corners of the planks – being careful to preserve the lines of the “step”.  One exception was that I knocked down the sharp corner between planks numbered one and two on the inside of the hull as this joint was going to be bridged by the fibreglass cloth re-enforcing for the bottom of the hull.

Reading my building bible had made me apprehensive about the process of glassing the bottom of the hull. The suggested technique was to pour on a quantity of epoxy resin and then to brush that out – adding resin where the cloth was not properly wetted but removing resin where the cloth was floating. It all sounded rather hectic and off-putting with inevitable variations in “pot life” making things just that bit more exciting. By ignoring the book and following some good alternate advice the reality was very different. Unhurried and straightforward, with the inside of the hull only slightly more awkward than the exterior.

Glassing the hull:

Let me describe the process, starting with the exterior where only the number one planks need the application of glass cloth. First, I applied masking tape to the edge of the number two planks. I found the best tape for this purpose was a plastic based one intended (I think) for use when painting windows) although a paper based tape would be fine and was what I used elsewhere.
 I had taken my roll of glass cloth into the house and taken advantage of a wooden floored corridor to cut the roll into two strips - one a little wider than the width of the two number one planks at their widest. The other strip I was confident would be wide enough to bridge the bottom on the inside. I laid the narrower strip along the hull and trimmed it so that the edges protruded a little beyond the masking tape protecting the edges of the number two planks. Material from the ends of the strip was going to be used later to cover the plank ends where they meet at the bow and stern.
My only other preparation was to trim a cheapish paintbrush so that the hairs were only 15mm or so long – giving me a mildly stiff brush which would not pick up too much resin. If you follow on and do things as I did them, then it is worth preparing three such brushes – sizes are not important but I found those with a 5cm width to work very well. If you clean the brushes after use then they can be used again later in the build process.

I mixed a small batch of epoxy resin (four pumps) in a pot and then, starting in the middle of the canoe at the centre line, I began to wet out the glass cloth using my modified paintbrush. Work enough resin into the cloth to make it transparent but not enough for the resin to build up on top of the cloth. The idea is to wet the cloth thoroughly but to leave a slightly matt finish – certainly not glossy. Continue working towards the outside edge of the planks and towards both the bow and stern. When you run out of epoxy – just mix another batch in the same pot and keep working. You can adjust the mix quantity towards the end. By mixing small batches you can take your time, working steadily towards the finish.

All you have to do now is clean your brush (if you have the relevant solvent) and wait for the epoxy to start to go off.  This is also a good moment to cut two strips of glass cloth from the spare ends “on the bias” to cover the stem and stern. The strips should be cut at 45 degrees to the weave of the cloth as this will maximise the number of threads crossing the plank joints while also being easy to stretch around the curves. 

Depending upon the ambient temperature your wait might be just a few minutes or even a couple of hours. When things feel right, load a Stanley Knife with a fresh blade and use this to cut through the resin and glass at the edge of the number one plank – peeling the excess glass cloth away with the masking tape. The way the planks are set makes this particularly easy on the outside of the hull.

Mix another small batch of un-thickened epoxy and paint a thin layer onto the planks at the stem and stern where your bias cut strips of cloth will be located. (This was why you needed the second prepared brush.) This will help hold the cloth into place while you wet it out and stretch it to shape. Lay the cloth pieces over the epoxy and then wet them out. Then I found it simplest to manage the final shaping and smoothing using my gloved hands.
I also decided to double up the glass on the keel by adding a length of woven glass tape down the centre line of the hull. I cut the tape to length and then stuck it in place – taking advantage of the fact that the epoxy from the initial layer of glass cloth was still just tacky. I then took up my third prepared brush and wetted out the glass tape, working from the middle of the boat and using small batches of epoxy just as before.

Thus I was able to re-enforce the bottom of the canoe in a single, rather pleasant working session – although I did manage to get through five pairs of protective gloves.

Tuesday 23 August 2011

The prototype single

Just a couple of pics to prove that the prototype floats.



Thursday 11 August 2011

Over Engineered

I have been working on a kayak loader as we are trying to manage with only one vehicle. I like the general idea of the Kari-Tek Easy Load but wanted to be able to adapt the loader to different car and kayak combinations. Prototypes came and went until I got to this:

Prototype kayak loader
Most of the aluminium and the sliding mechanism is from a cheap step-ladder (much cheaper than buying stock), with a few bits and pieces of scrap. On the plus side, it is relatively easy to load one fully laden plastic kayak - but when you add the second kayak, it is hard to lift and slide. On the subject of sliding, the mechanism attracts sand (of course) which you can safely say, does not help.

There are various solutions to the problem on the web - mostly ways of protecting your car as you slide the kayak onto the roofrack - with one bright idea - that of loading from the side - where the rack is much closer to the perimeter of the car. This plus an observation from Catherine along the lines of 'can't you just have supports that slide out from the roof bars?' prompted the following design:

Simple Kayak Loader
The roof bar extensions are just a push fit, and the cross bar stops the kayak rubbing against the car - simples. If you have central supports on the bars (I normally do, but not shown in this picture), you just load the second kayak from the other side. So, no moving parts, light and easy to pack away - cheap.

Time to turn the old prototype into a loft ladder.


Wednesday 4 May 2011

Harpoon

Boat building and paddle making carry on in the background, but last week we were contacted by Nigel Dennis to see if we could make some harpoons for the Anglesey Symposium. Now, I am always up for making something new, but have never seen a Greenland harpoon, so a quick search for some pics on Google, and out for some testing with Phil Kinvig who has just built a strip cedar boat.

Harpoons by the Anglesey Stick Double

Harpoon and throwing stick on the foredeck

Rich attacking some seaweed



Wednesday 2 June 2010

Newest drill/driver does a desmond

My newest cordless drill/driver has got to the point where you have to put the battery on charge whenever you put it down - which means you have to have the charger with you at all times - rather spoils the idea really.

This is with the 'good' battery - the less good one was pretty near useless from new (I suppose the manufacturers found a good way to get rid of the batteries that failed QA), and of course a replacement battery costs more than a completely new unit.

Which is why I have a couple of past casualties lying around. What to do with them?


Ok, my solution is not cordless, and not as portable - but boy, feel the torque from those DC motors feeding off a real battery.