My posts telling the story of my stitch and glue lapstrake canoe construction are likely to slow as the main stages in the construction come to and end and I start in on the sanding and finishing. Before we get to that stage though there is still quite a lot of work to do preparing for (just about) the final addition to the structure - the gunwales. I still had to add some epoxy to the joints that had not been completely filled but first I deviated from the instructions. I knew that the European oak inwales and outwales were probably going to be a little bit difficult to bend and that this would stress the top plank in particular as they were bent to the boat's final curves. I decided to add a small fillet to both the top two plank joints behind the bulkheads - I also added a narrow glass cloth reinforcing strip. Why the addition? Well, as a first time builder, I could not be sure that those rather tight joints had been completely filled with glue and the last thing I wanted to happen was a joint failure.
With these additions in place, I then topped up the plank joints that were not completely filled the first time. The construction book suggests that you should use a slightly thicker mix than the glue used for the first shot but to apply it in the same way - using a syringe. I decided on a different tack and thickened my epoxy with lots of colloidal silica. I then used a pallet knife to push the thickened mix into the joints - using the knife to level off to what I hoped should be the correct hull lines.
Perhaps foolishly,I did all of this epoxy work in the lowest ambient temperature so far - which had an interesting effect. The epoxy cured nicely in the usual 24 hours or so but a few days later I noticed that there was an 'amine blush' on the surface. This waxy layer needs to be cleaned off with detergent and water. It is strange stuff though and I will try and avoid a re-occurrence by working at higher temperatures in future.
I took advantage of generally higher outdoor temperatures of the next couple of days to move the canoe hull back to the barn while I first of all cleaned my office and then started work on the inwales and outwales. First off, I sanded off any epoxy that had extruded from the scarfed joints and then I inspected each length of oak to decide which piece was going to do which duty. I then used the router to round over the top and bottom edges of the outwales. I found it was best to clamp two lengths side by side to give me a good platform to rest the router base on. After routing, I sanded the top and bottom edge to remove any saw marks left over from ripping the lengths from the original plank.
While I want to finish the corners of the inwales, I could not round them at this stage as the pieces needed to be fitted to the boat before I could determine the locations of the decks and the seats. I want to leave the inwales square under the decks for maximum adhesion and I will also need to fit "doublers" to increase the width of the inwales where the seats will be fitted. It is not clear yet if I will leave this finishing until after the inwales are glued in place or if I will try and sort them out before that.
I then set about clamping one of the outwales to the outer edge of the canoe hull so that I could cut it to length. First off, this looked somewhat tricky as the oak lath had to bend in three dimensions to follow the curve of the top plank as well as the twist of the hull. In practice it turned out to be fairly steady although a couple of extra arms would have been helpful from time to time. When the outwale was clamped and cut to length I could admire the improved curve of the hull - not quite perfect yet but definitely smoother.
Offering up the first outwale
I then clamped the second outwale in position and cut that to length. The next task was to stretch a string along the length of the hull to measure the mitre angle that would need to be cut between the inwales where they met at the stem and stern. With this measure I could cut the first mitre on the first inwale and then start working it into the boat. The involved removing each clamp holding the outwale in turn and the adjusting it to hold the inwale in place as well. One I neared the other end of the canoe I could mark and make the cut to complete the inwale and to set it snugly in place.
With the inwale in place, the top edge of the hull on that beam took on a very pleasing curve from end to end. Then it was just a case of following the same routine with the other inwale. Wow do you need a lot of clamps to build a canoe. It is very clear that I will need all that I have just to glue one gunwale into position if I want a good fit.
After that I was out of time and could not start in on gluing the gunwales into place. In any case, it was clear from my efforts so far that I was going to need an assistant for this particular process. Next weekend I am visiting the UK which means no work on the canoe but it will allow me the opportunity to pick up some materials difficult to obtain locally - some good yacht varnish and some coloured epoxy top coat for the outside of the hull. In the mean time the gunwales can stay clamped in place which might reduce some of the tension in the wood and make the gluing less of a fight - well maybe.
looking good!
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