Captain's Chair Part II - Looking for advice

DonGargano

Hello fellow boaters.  We've had a pretty good season here in the Ottawa/Rideau area of SE Ontario.  Still a few weeks left...I'm optimistic before I take my 212 Cuddy out of the marina.  
Some of you may recall I had to work on re-securing the Captains Chair to the deck earlier this summer.  I'm neither happy nor secure with the stability and strength of the steel braces I bolted the seat to, so I am considering a bigger project;  

I don't think the entire floor has dry rot, but I'm not even sure I know it when I see it!   I am considering having someone replace the whole floor.  Not sure it that makes sense financially on a boat that only cost me $4000. 

As a DYI, I'm contemplating constructing a larger (More stable) wood/fibreglassed base - bolted to the floor.   But wouldn't that mean having to bolt it in place from the underside?   

Looking for some recommendations and advice based on all the experience out there.  

YYZRC

Is the floor spongy?

LaRea

I'd do a larger mounting plate.  Maybe 2'x2'x3/4" marine plywood, primed and painted with white BilgeKote or some other marine epoxy.  

PickleRick

I wouldn't spend the money on marine ply.  Due to costs many of the custom wood boat marine builders are not even using marine ply. 

Cdx board (closest to 3/4 you can get) uses the same waterproof glue. Once you treat it with epoxy resin she's good for 20 plus years so long as you seal the mounting holes properly. 

DonGargano

Not sure I’d call the floor spongy.  I’m a heavy guy, and the floor and chair flex significantly when I’m sitting.  So certainly not a rigid floor. 

So if I’m going to build up a larger mounting plate, how am I securing this to the existing floor?

GMSLITHO

treat all the wood with Total Boat penetrating epoxy

PickleRick

You need to first remove any and all rot. 

At that point I'd both epoxy and thru bolt the reinforced board to the floor. 

You should be able to have 2 defensive linemen tap dance on that floor.