Building the coaming is one of the more difficult bits to make on a kayak. There are several methods, some use strips of cedar or ash, others use plywood; I'm trying out a new method.
Using spacers cut from 3mm Foamex [pvc sheet] I tacked them around the riser with spots of hot glue.
... superglue was used to stick on another sheet of Foamex from which the inner was removed so it fitted neatly onto the spacers and was level with the top of the riser. It was covered with duct tape to act as a release from the epoxy.
Previously I used polystyrene foam to build up the shape but the foamex is a harder surface and easier to use the squeegee on without getting bumps in the layers of glass.
The spraydeck lip was then built up from layers of 200g cloth. I added some black epoxy tint to the later coats, which will prevent light spots under the final layers of carbon fibre.
Finally the coaming is positioned onto the riser and taped down while the epoxy sets.
I fabricated the hatch surrounds from foamex too, then covered with duct tape again..
The surrounds are made from about 8 layers of 200g cloth. They have to be strong; a 1m wave crashing onto the deck has some weight in it, so lightweight construction goes out the window in this instance
Plenty of thickened epoxy and lots of clamps hold it in place whilst setting. After some filling, filing and sanding, a layer of carbon fibre [reassuringly expensive] is applied over the surround. Here's the front hatch so far.
This method is explained in more detail by Ross Leidy in his Whiptail build on his excellent Blueheronkayaks website.
[171hrs so far]