This sketch is a concept drawing of the mold for the rowing deck. Of course it is a negative so that when the carbon fiber is formed onto it, it will form a positive with the finished side against the mold.
To form the mold, you need to start with a positive shape, or what's called a plug. I debated building a plug, but then decided that I could use the boat as the basis for it. I used styrofoam board to form the decks and sloped transition surfaces, all held temporarily in place with masking and duct tape. The location of these are critical parts of the boat design.
The mold surface is going to be made of fiberglass, which I have to cast onto the plug. I got stuck for awhile trying to figure out how to ensure that the fiberglass mold would let go of the plug. I discovered thru experiment that fiberglass releases easily from clear vinyl, so I lined the plug with window-vinyl. Because it's see-thru, it is handy material for this work!
Then I laid 6oz glass over top and applied epoxy resin.
Today I checked the result...
...so far, so good!