I've seen some of those fiber glass coamings, was it molded? It's hard to say what the shape is like without knowing the model and manufacturer. The manufacturer might have advise, probably to come in and buy a new boat....however, I like canoes with wood trim, might you use methods described in the wood boat literature to accomplish your goal? You may try drawing the shape you want on card board or poster board, use that as a guide to draw the shape out on the boat, and on some wood stock, then take a jig saw or rotozip to your exisiting cockpit, and cut it to the shape you want. then make an inside (under-coaming) coaming and use it as the bottom layer, sandwich the fiberglass next, then a number of other pieces laminated to give you the height you want, then, the spray skirt lip on top of it all. Both Nick Shade and Ted Moores explain a version of the process in their books. Look up Kris Kazinski's treatment of the subject in his book. Of course you might find something you like from one of the kit boat manufacturers. That would be how I would approach this. Sincerely,
Bill
P.S.
I'd be careful not to let the material on your boat tear or crack. Use a sharp jig blade, stablize the boat and surface to be cut as best as you can. Ask the guys who rent fiberglass boats how they make repairs and what pit falls to watch out for. Good Luck.

: Does anyone have instructions/thoughts/plans about how to construct a
: cockpit, including coaming, for a fibrglass kayak. My boat was actually
: built for someone with shorter legs than mine and so it does make it a
: little difficult to get into at waters edge, resulting in more than one
: grazed shin! Any thoughts about how to "build" a larger cockpit
: would be appreciated.

: Mark.