Here is a bit of a summary of progress so far with building our cabin top for the Etchell. We spent quite a bit of time agonizing over the smallest of angles and curves that would make up the cabin top shape. It’s amazing what a difference changing these details can have on the overall form. Eventually we settled on a final form and using Rhino 3D modeled this up in order to extract enough detail to construct a former for the cabin top.
Our approach to this cabin top is to build a male former, then tack on foam core and apply layers of glass on the outside. We would then remove the former and apply glass on the inside. We will need to do quite a bit of finishing on both sides – but it saves us from having to make a very high end former.
The former was constructed using MDF board and some left over strips of Western Red Cedar that we had lying round from an earlier project. We were able to get sections from the CAD drawing and then mark and cut these in the MDF. The Cedar strips where then curved around the edge to support the foam.
Here are some pics showing the former constructed and ready to apply the layer of foam.
After building the former we applied the layer of foam. This is really nasty dusty stuff but Nick assures me it has splendid structural qualities. We put down a layer of resin proof tape at any contact points and then held down the foam with small panel pins and the occasional screw. The aim being to have minimal disruption to the foam core when we remove the inner former.
With all the foam on we applied a layer of resign proof tape for the mast and cabin door cutouts. Here are a few shots of the foam ready for applying the outer layers of glass. The indent around the edge will house a wooden rail.
With the foam on we then applied a 2 layers of combination (chop and weave). It was a tricky job to make sure that there where no air pockets in between the foam and the outside layer. Here is a fairly blurry shot of the top layer on.
With the outside layer on we then flipped the piece upside down and stripped out the former. We then cut out the holes for the mast and cabin door. The resin proof tape worked a treat here. The only tricky bit was making sure the holes where properly lined up. Thankfully the tape gave a clear indicator of the outline of the 2 holes. The edges are cut at angles to improve the structural integrity of the form – or so Nicky tells me.
At this stage the shape was still quite flexible. The real advantage of this sandwich construction only comes with application of layers on both sides of the foam. In order to make sure that the original curves of the former were preserved, we build a female frame work around the base of the unit. This kept the sides from sagging and made sure the piece was nice and secure whilst applying the inside layers of glass. Here are a couple of hazy shots of the glassed interior guarded by our mannequin🙂
So – thats the progress on the cabin top. I’d dearly love to have it fitted on the boat at this stage – but it seems this project will be a slow burner. Still – progress is progress and we keep ticking of the tasks.
In the meantime – Nick has made great progress on the hull. Half our boat is in a gleaming, if slightly patchy, Mauritius Blue. More on that to follow!