dry rot repair?

While I had my rear seat out, checking on my fuel tank sender, I noticed what looked like a damaged spot at the aft of the boat starboard of the exhaust tube. Upon further examination I found about 6 to 8 inches of what I believe is 3/8 " plywood covered in fiberglass that has dry rotted from 30+ years of people getting in, and dripping off over the back seat.
I can see an attempted repair, either by my PO, or his PO where he attempted to seal up the area with white silicone.

My question is: What would be involved in repairing this rotten area?

Is repairing it worth it, since the floor is not soft in the area? Should I just take the back seat cushion out after pulling the boat out of the water to let the area dry out and not worry about it.

I'll take a picture and post later...

Thanks,
Anthony

Pete, I wonder if you can get silicone in 5 gallon buckets, with a dispensor

8122pbrainard wrote: Anthony, Get the picture posted. From your decription, I'm having a hard time figuring out where this rotted ply is. On the inside of the transom? Depending on what the pywood is for will determine if it's worth repair. Yes, silicone isn't a repair! It amazes me sometimes what some people consider a repair!!!

Sorry, no picture yet. I haven't drug my butt back out to the garage with the camera. I'll do it tonight. In the interim, I'll see if I can more clearly describe the area and nature of the damage...

The damage is not in the transom area. My boat has dual exhausts. The hull has "walls", for lack of a better term, that define the area the exhaust tubes live in. The inside "wall" is the stringer, the outside "wall" is where I have noticed the issue.
The damaged/rotten area is perpendicular to the bottom of the hull. It is located forward of the fuel tank directly under the starboard end of the rear seat lower cushion in the last six to eight visible inches (before it goes under the fuel tank area) of the starboard "wall" of the cavity in which the starboard exhaust tube lives.

Uggh...I'll get pictures tonight.

Sounds like secondary stringer rot.
Your exhaust tunnel should have drains to the bilge and they sometimes clog. If they did, and your exhaust tubes leak, then you collect water in the exhaust tunnel and it cannot get out.
This was happening with my 80 but I found it before rot started.

She's a '76 Martinique. Looks exactly like the one in the brochure.

Only 530 hours on the PCM 351, and she was garage kept since at least 1981.

Sure seems like very few of the wooden stringer boats escape this. What happened to the guy with composites? I was looking forward to seeing what he found.

Anthony, Id say it's planning time with the sun out!

almabes wrote: She's a '76 Martinique. Looks exactly like the one in and she was garage kept since at least 1981.

Like the guys have stated, the garage kept doesn't make a difference unless the boat has never seen the water.

Anthony,
Yes, you are correct that keeping it inside instead of constantly being outside wet will make a difference. However, the way you stated it being garage kept since 81 sounded like you thought it would be immune to rot. That's not the case. Just as Seb (kapla) said, water gets in and never seems to dry out.

Take a look around wherever you can at the stringers. Look for loose and cracked glass covering them. Under motor mounds and where the cross members are notched into the stringer tops are good spots. Get back to us with anything you find. If there are some bad spots, then it may be time to do some test boring (drilling) into the wood in spots to see what comes out. Hopefully the one spot you do have a problem with will be the only one. At this time, my gut feeling is you don't have to react now but it's inevitable in the future.

The existing spot would be tough it do a repair without pulling up the floor. About all you can do now is to clean up the top edge (especially the damn silicone a PO put on it) and give it a CPES treatment. Hopefully it will soak down deep into the bad spot. Drilling some small holes down into the wood would help get the CPES deeper.

CPES at Jamestown

Thanks Pete. I thoroughly appreciate your wisdom. Also, thanks to everyone else who has added thier two cents.

I'll drag my butt back out to the garage and poke at my stringers. I'll post pics of anything I think looks questionable.

The moral of this story is: Never ever look in the bilge. "Ignorance is bliss"

Sam

Anthony,
The problem with bad stringers is that you end up with stress cracks in the gell. Mostly along the waterline. Much harder to fix.

If it were mine and I was not ready to replace the stingers, I would probably take a dremmel tool and cut the glass from around the suspected rotted area. If I found good wood, like you suspect, I would cut out the rot and cut in another piece. This is not a high stress area and if the rot is minimal you can replace the rotted area and glass it in again. Use CEPS to protect the new and old woods.

I only say this because it sounds like you are not ready to do a stringer job and may not actually need one. With these stringer replacements, you have to ready for them. You may be able to patch this area to extend your boating time.

I agree with Pete and the rest. If you have rot there, you have it other places as well.
As Pete mentioned, go over your stingers carefully and look for cracked glass areas. Check the wood behind them as well. This area is not really a stress point but you could have other areas of rot that are..
Good luck