: I recently received an '80's vintage plug and mold fiberglass kayak in good
: shape. I'd like to enlarge the cockpit opening and install a new coaming,
: seat and backrest. The original seat and coaming was a one piece affair
: that fit in the deck opening and was held in place with a few dabs of
: epoxy.

Cut thru that epoxy --if it really was epoxy; might have been polyester resin--and pull out the old coaming and seat.

Get a big sheet of paper (tape together a few sheet of newspaper) and head over to your local kayak shop. Find a popular kayak and see how well you can fit into that cockpit opening. If it is a good fit, pull out your paper, write down the model and brand of the boat you are trying, and trace the shape of that cockpit opening. Use your tracing as a template when you cut into your boat. When you are finished your cockpit coaming should be the same size as the one on the boat you tried. Now, when you want to buy a spray skirt, you will know which one fits your boat--'cause your cockpit will be the same size as the more common one you tried out.

: The inside width of the coaming is 14" and I'd like to widen
: it an additional 2-1/2". Any help or suggestions fro additional
: sources of information would be appreciated.

There are some blades for sabresaws which do a real good job on cutting fiberglass and plastics. Check those made by Bosch. You should be able to find good blades in both the universal mount and the "T" mount. A bad blade is a terrible thing to play with. It juut makes a mess.

Good luck on your project.

PGJ