Fixing soft spot with flex seal

[Father's Day]

Ok here we go. My brother has a Luhrs with a soft spot on the deck. This is not his first boat, and he replaced floors before. Marine grade plywood wrapped in fiberglass the whole nine yards. It's now 2022 why not use marine grade plywood and put flex seal on both sides. I know a few heads just exploded but hear me out. The whole purpose of wrapping it in fiberglass is to protect the wood, that was years before they had this product, which by the way is pretty damn good for sealing the wood in rubber. He thinks I'm crazy but why not give it a shot. If it doesn't work we could always go back to wrapping it in fiberglass. Curious to have some input on this.
Thanks stay safe and have fun

 

[seasick]

Yup, my head exploded.

The theory with the glass and resin is that the resin seals the wood from moisture. Epoxy resin when hardened is very brittle. It's the fiberglass cloth that gives it strength and rigidity. If you coat a piece of plywood with resin only and subject it to stress, micro to not so micro cracks will develop and moisture if present will seep into the cracks.
In addition to the above, if multiple layers of coring ( like plywood) are used, the resin AND fiberglass between the wood panels insures that small voids or unevenness will get covered with resin since the cloth will compensate for the uneven core surface

 

[DennisG01]

Yeah, I wouldn't be using a relatively new product in an untested way. If you guys want to be the guinea pigs, go for it! But I can't imagine a rubbery product performing (long term) ANYWHERE near as good as a resin that soaks INTO the wood.

How long have you tested Flex Seal in constant exposure to UV, salt, etc? Fiberglass has been tested for many, many decades and is still performing excellent. Issues of wood rot are not due to fiberglass, itself - it's do to improper sealing - whether originally from the manufacturer or an owner drilling/screwing into it and not properly re-sealing.

 

[blindmullet]

I could see on a small lake boat. A lot of the pongooners have outdoor carpet over PT wood anyway.

As others have said, you wouldn't have any strength. The deck would be a trampoline.

 

[DennisG01]

To add more on the strength issue - even though it's been said, it deserves repeating... the strength from glass/wood/glass is that the core (wood/foam/whatever) SEPARATES the two layers of glass. The core, itself, is not really the strength - it's the fact that the two layers of glass or rigidly separated from each other. This is why when coring gets rotten that the floor gets spongy - the bond between the core and the glass has broken. Using a rubber coating over the plywood adds zero strength.

 

[Father's Day]

To add more on the strength issue - even thought it's been said, it deserves repeating... the strength from glass/wood/glass is that the core (wood/foam/whatever) SEPARATES the two layers of glass. The core, itself, is not really the strength - it's the fact that the two layers of glass or rigidly separated from each other. This is why when coring gets rotten that the floor gets spongy - the bond between the core and the glass has broken. Using a rubber coating over the plywood adds zero strength.

Point taken just threw it out there, we will be glassing over weekend thanks guys

 

[DennisG01]

Point taken just threw it out there, we will be glassing over weekend thanks guys

Nothin' wrong with askin'!

 

[seasick]

What do I do with my exploded head!