Paul Gartside 18' Racing Gaff Cutter • Cabinversion designed by Dominik Gschwind

2012-10-27

Week 14 - Deckcovering / Coamings

With the following tasks Glóey changed her look quite a lot. She has no visible filigrane skeletonstructure anymore because we've covered the deck with marine plywood (Robbins Elite Ply).
But let's have a look step by step:
Before glueing the formshaped plyelements to the deckframing we did some painting- and varnishingwork. The reason for this is that it is just so much easier to do that now than later when the boat is covered.
The framingcompartments on the plywoodunderside got 2 coats of primer and 2 coats of EPIFANES traditionel 1-pack paint. The douglasfyr of beams, beamshelf and carling got 3 coats of EPIFANES Rapid Clear and thereafter 2 coats of EPIFANES clear varnish (1-pack), sanded between the coats with 320 grit sandpaper. In the buoyncetank at the bow we've painted 2 coats of SEATEK Epoxyprimer.

Beside that we also fittet the 2" GRP tube for the rudderstock through the sternpost and the kingblocking. It is a fiberglasstube with nylonbushes at either end and with rubber o-rings inside the bushes.

And this is how the boat looked like with a covered deck (underdeck).
After glueing the ply on a little overlapping we trimmed the edges with a blockplane on the convex outside and with a good old Stanley Nr. 79 side rebateplane along the concave inside.
The inside had to get accurately plomb to become the future jointsurface of the vertical coamings.
Coamings are the structural elements on the side of the cockpit and the cabin (coach) which are joint to the carling. On the photo to the left you can see how we were scribing the complicated shape of the coamings to a piece of flexible 3mm hardboard. For the coachroofoutline we've built a jig which could now be used for the template as well as finally to screw the overhight plywood-coamings on.
Materialwise we used 2 sheets of 9mm marineplywood (Robbins Super Elite) which hat to be scarfed to manage the necessary length. So the coamings got 18mm strong!
Normally Lloyds recommends a 1:8 ratio on plywoodscarfs but we decided to use 1:10 just because of the stresses in the material caused by the bending.This quality of plywood is an absolute pleasure to plane and the veneers help to get the scarffaces really flat. Because of the limited possibilities in the workshop we had to glue the scarfs of those long elements on the floor which was covered with the loftingboards. That methode doesn't allow real clamping and therefore we used heavy pieces of lead to create the necessary pressure.
Some improvised helpingconstructions gave us the possibility to clamp the coamings when glueing them on to the boat. On the inside we also used silicon bronze screws in to the carling to support the joint. These screws have such a nice look with that slightly red bronzealloy that they also will be a decorativ part of the interior.
In my design of the triangleshaped coachroof I wanted to have an elegant frontpost which unfortunately is a bit tricky to fashion. Simply because of the fact that there is so much bendingpressure on the coamings while glueing them. As visible on the photo we solved the problem by trimming the "first" nose off with a chisel and blockplane and glue another piece of straightgrained sapele mahogani on which finally could be trimmed to it's endshape. The sectionlike photo also shows that the shape of the frontpost was choosen in a way to get max. gluesurface inside the coamings.
Along the cockpit it was a straight forward process to fix the coamings because of the existing possibilities to use conventional G-clamps.
The topside of the doubleplywood will here be covered by a bendable strip of sapele after shaping it later to it's final lines.
And this is how she looks with coamings...