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Seat base replacement for 1982 Checkmate Diplomat I/O


New member
I recently got a 1982 Checkmate Diplomat I/O. It's been stored uncovered a lot (apparently) and has some rotten seat structure and bad carpet. But the main challenge I ran into recently is the passenger seat base. This is the swivel chair with aluminum base. The base screws into a small platform with six screws. That platform is connected to the floor of the boat (or integral to it?). Anyway, that platform is in bad shape and it's "soggy." The seat moves and you can't tighten the screws.

Does anyone have recommendations for rebuilding that platform? It looks to me (because I drilled into it to mount some wall anchor type things) that it is fiberglass.

Would it be feasible to replace it with marine plywood/epoxied? How would I mount that to the floor if so? Any ideas of how to get this seat safer would be greatly appreciated!



Well-known member
The wood inside the platform is rotted, that's why the screws can't get a grip. You'll have to remove it and re-glass in some wood to make a new base.

The unfortunate news is more than likely a significant portion of the floor is rotted out as well, particularly if it was stored outside most of the time. So this project may quickly expand once you start working! Wait until you see the price of marine plywood right now.


Well-known member
Cut off the platform from the floor, build a new plywood platform and re fiberglass it back down to the floor.

Hopefully someone did not try longer bolts/screws that would penetrate through the platform and into the floor creating a pathway for water into the floor causing it to rot.

Those old bases were just 3/4" marine plywood with capture nuts in them for the seat base bolts to screw into, They are very easy to recreate and glass to the floor.


New member
Thanks! I know nothing about fiberglassing and that makes me nervous. I do have access to a 3D printer though. I was thinking about cutting out that old platform and cleaning up the floor. Then 3D printing a nylon replica with metal threaded inserts embedded and gluing that down with epoxy. Does anyone think that is a good or bad idea?


Well-known member
The metal inserts may pull through the nylon and the whole thing may pull off the floor if the epoxy does not hold? But you have the right idea about going to a material that does not rot.