Cover over gas tank, should it be soft?

[Parrot6909]

Well, here is my first in what is sure to be a ton of ?'s for you guys. Lets introduce the boat, 1986 V20. The floors and transom are solid, but there is a very noticable flex in the area above the gas tank, 1/4 to 1/2" of sponginess.......Was it designed that way or is it time to rip it out and redo it? Just an FYI for size, I am 6'3" and about 225. Not hopping on it, just walking over it....Help is appreciated!

[Repirts]

No. No part of the deck was designed to flex. I assume you mean the hatch over the tank. Mine is pretty soft too. Pull yours out and it will probably be like mine- heavy and full of water. I'll probably pull mine, cut the skin on the back side, pull out the rotten core and replace with plywood and resin. Looks to be a pretty easy job.

[Parrot6909]

Yeah, I didn't think it should flex but being a newbie.....Thanks!

[Seacrets]

I did two (85 & 86). It's real easy. You won't find one piece of plywood, but several small squares. Good luck.

[Vic]

All you need is a grinder and a chizel to save the top skin. and glass in the new wood.

[Franco]

I had the same problem with mine. It seems to me that it was caused when they cut the holes for the deck plates. When I fixed mine in cut those hole about a 1/4 inch larger abd glasses the edges. I might also recommend that you use a grade piece of plywood that has as many plys as possible. I happened to have a piece of 1/2" cabinet grade hardwood plywood - 7 plys -
very stiff and stable. ( I build cabinets and furniture as my other hobbies) glassed it in using west system. Works like a champ and did it all in an afternoon

[rb437]

I had to do the same repair on my '89 last year. unfortunatly the previous owner let it go long enough that the hatch began to crack. A single sheet of 3/4" plywood glassed in will make yours plenty strong enough.

[reelapeelin]

Isn't there something besides wood that can be used for repair like that...what's the rigid board that's used in transoms, etc...

[offshoremag]

You can take your pick of core materials, depending on what you want to pay. But marine ply is fine. There are various grades, you don't need the best, but might as well get it, since price difference is worth it. Should last the life of the boat if you do it right.

If your deck is still good, it will go bad eventually if you're not careful. The best thing you can do to preserve your deck and fuel tank is replace all those seive-like snap-in deck plates with proper Becksons with screw-on lids. Bed them well in 3M 4200 or Sika equivalent and keep the 0-rings fresh.
When you remove the old deck plates follow West System procedure for mounting deck hardware, i.e. remove exposed core around the edge of the hole and pump thickened epoxy into the groove. *If you do that, even if your deck plates leak, no water will get to the core. More $1,000 projects begin because of through deck fittings (stantion screws, cleat hardware, etc.) that leaked into the core. No exposed core -- no problem.

Likewise, if your replacing the core in your deck section, use only solid glass at any spots where through-deck hardware will be mounted. Most good yachtbuilders follow this procedure so as to avoid the soaking core problem altogether.

Here are some core manufacturers:
http://boatdesign.net/Directory/Materials/Fiberglass_and_Resin/Composite_Cores/

[reelapeelin]

Thanks, OFFSHORE...don't need that info just now, but bookmarked for later...good stuff... ;) ;D...

[jrhiner]

My son repaired the hatch over the fuel tank of my '86 last year. One piece of 1/2 inch plywood, glassed in, worked just fine. Be sure to take the wood as close to the edges of the hatch as you can. Otherwise, it will continue to flex. This year we did the hatch over the fish well between the pedestal seats. Good luck.