Tuesday, July 3, 2012

Installing the bulwark cap

Wharram calls for a strip of plywood glued on top of the bulwark, but Wharram doesn't work with a traditional boat builder. Trevor suggested a purpleheart cap to match the lashing strake, and we agreed. And it looks wonderful.

The cap is attached to the top of the bulwark with sikaflex, and then with countersunk screws. Since the screw holes are then plugged, it hasn't been oiled yet -- oiled wood can't be glued with carpenter's glue, and that's what is being used to hold the plugs in.

The process required quite a bit of prep, since we didn't want too much sikaflex (or any, really) dripping on the beautiful paint job.

Here it is, masked with newspaper to keep the sikaflex off.

Installation is a two-person job. Since the cap has to curve quite dramatically over the length of the hull, and purpleheart is really strong wood, it's under a lot of pressure. As you can see, deck and cabin top is painted too.

And this is what it will look like -- a wonderful contrast with the Hatteras White bulwark. 

The decks are painted now too, and so is the cabin top. It's all Hatteras White, flattened to a matte finish the same as the hull. Photos to follow!

Lashing strake

The lashing strakes are now installed. And lovely lashing strakes they are, too.

The lashing strake is what keeps the beam lashings from popping off. Since the lashings hold the beams to the hulls, and therefore do a lot to hold the boat together, this is important. That said,  there are options. Smaller pieces can be used below each of the beams, or a continuous piece can run from the forward to the aft beam.

We chose the continuous piece, made from purple heart. It's not all one piece of wood -- there are scarf joints involved. It's finished with five rubbed-in coats of boiled linseed oil, which has darkened the purple of the wood to something nearer brown. Oxidation will apparently cause it to go to dark chestnut when it is out in the sun.

It's held on with sikaflex and carriage bolts. No distant supplier for this -- everything came from the Harbour Chandler in Nanaimo.

The sikaflex is black (it comes in various colours) and is exceedingly sticky when wet and rubbery when set. The carriage bolts are regular carriage bolts -- galvanized. 

Once everything is in place, there's lots of clean-up as sikaflex oozes out when the bolts engage.