Flotation foam under cabin floor

[Krennen]

First post, so please bear with me. I acquired a ‘84 SRV-260 Express Cruiser for pretty much free. I have been doing little things here and there, but I pulled up the carpet in the cabin floor and there appears to be a series of holes drilled. If I push the plug on the top of the hole through, there is foam under them. Is this original from the factory or did someone add foam at some point? If this is original, is this just a false floor? I am only asking because a small amount of the foam is wet, I am trying to decide what my next steps should be.

Thank you in advance.

 

[jmcdboater]

Welcome to the club, lots of good data and suggestions available here, lots of very knowledgeable boaters! How big an area are we talking, here. You said ‘series of drilled holes’, how many? How big are the holes? How deep?

 

[keokie]

Back in the 80's, Sea Ray was building a stringer/floor system primarily out of plywood stapled together, then fiberglassed over (sometimes only with a chop gun. Then they would make holes about two inches in diameter and add an expanding foam. The holes would then be filled with bondo. The foam served many purposes. These were primarily floatation, strength, and preventing gas fumes from accumulating in hollow areas.

The down side (and this is a very big one). The foam readily absorbed water in any areas that weren't totally water tight. The primary drawback is that would lead to the complete rotting of the wood in relatively short time.

If you have decent carpentry/cabinetry skills, and a ton of time, that whole stringer system can be rebuilt without a ton of money. But it is a big job. I once re-did most of the floor and stringer system with my father on an '81 210 cuddy. It was a tremendous amount of work. The finished product came out excellent. However, we found a few years later the few areas that we thought were dry and unaffected began to rot, and even rotted partially into the areas we replaced. None of the new foam (or old foam that still remained) was wet at all. Turns out wood rot is a spore brought in by freshwater, but it does not actually need water to proliferate. Once it gets into the wood, it rots it to virtual sawdust. We should have torn out all of the floor and stringer system.

Salt generally kills the rot spore, but even with saltwater boats, it is usually freshwater that gets into the floor from rain, washing, etc.

Folks commonly assume with an old boat that the mechanicals are the biggest challenge, but in my opinion, structural issues are the real concern.

The 260 SRV was an outstanding boat in my opinion. The '83 in my sig was very similar, just different cabin/cockpit layout.

Honestly, after doing that project in the 21 footer, I would simply walk from another boat with dry rot.

Sorry for the bad news, but do your research, and assess your capabilities/commitment before putting money in this one.