Glassing over teak deck. Bad idea?

[Capt.Bill11]

Originally Posted by FF

I realized that the PO laid down 3/4 ply over the teck and glassed over that

Did your surveyor warn you?

You're a funny man!

[Marin]

Originally Posted by kulas44

What he found was that the decking added quite a bit to the structure of the deck, after removal it was a little "springy".

Yes, the teak planking adds a fair amount of stiffness. The typical practice when replacing a teak plank surface with fiberglass is to remove the teak, prep the top of the subdeck, then add two (or more if desired) layers of fiberglass on top of the subdeck and then put the non-skid surface on top of the final layer of fiberglass. The layers of fiberglass restore the stiffness that was lost when the teak planking was removed.

An acquaintance did this to his Island Gypsy. While two layers of glass on top of the exposed subdeck would most likely have been sufficient, he elected to add four layers. He did a beautiful job with his deck, probably better than the manufacturer would have done, and the result is a deck that is strong and stiff enough to land a plane on.

[BruceK]

Surely there is an immediate problem with different levels of adhesion to teak and caulk of anything put over a deck.

[Capt.Bill11]

One or two layers of glass will do little or nothing to restore the rigidity to a deck that has had teak removed from it. Glass just doesn't have that kind of structural rigidity to it. Especially in thin layers.

[Marin]

Originally Posted by Capt.Bill11

One or two layers of glass will do little or nothing to restore the rigidity to a deck that has had teak removed from it. .

Yes it apparently does. This is the standard recommendation from the folks who know what they're talking about on the GB owners forum, and it was the recommendation to the fellow with the Island Gypsy I mentioned from the fellow who was advising him on the project, the former chief engineer of Uniflite. The four layers of glass that the IG owner put on was way overkill according to his advisor but it certainly didn't hurt anyting other than add unnecesary weight.

But two layers of glass is the typical recommendation. By which I mean put on one layer with resin and let it cure, then put on the next layer. Not just two layers of fabric and then resin. Also, I don't know what weight of glass fabric is recommended for this. So it may be pretty heavy stuff, I don't know.

[Greatlaker221]

Maybe being a bit more specific when saying two layers would be helpful. There is 6oz, 10oz, chop strand mat, biaxial 1708, woven roving and more. All have different strengths and absorb resin differently. Personally, I would use layers of 1708 and polyester resin.

What do you all think about assuming most of the core is wet, use a circular saw to cut at the outside edges of the core, lifting the teak and top layer of glass at once. This saves lots of labor. Remove/replace the core and glass over with 3-4 layers of 1708? Thoughts?

[Insequent]

Originally Posted by Greatlaker221

Maybe being a bit more specific when saying two layers would be helpful. There is 6oz, 10oz, chop strand mat, biaxial 1708, woven roving and more. All have different strengths and absorb resin differently. Personally, I would use layers of 1708 and polyester resin.

What do you all think about assuming most of the core is wet, use a circular saw to cut at the outside edges of the core, lifting the teak and top layer of glass at once. This saves lots of labor. Remove/replace the core and glass over with 3-4 layers of 1708? Thoughts?

Depends on core. In my case it was end grain balsa, well stuck to both top and bottom GRP skins. It had to be chiseled out. Although where damp it came out easier and where rotten it could be scooped out! Other core, ranging from plywood to offcuts of timber might be quite different to remove.

Remove the teak as a first step, then use a drill to test for wet core - just work your way outwards from known soft spots until the drill cuttings are dry. With a map of how much core has to be replaced you can then plan accordingly. I replaced all my foredeck core, about 92 sq ft. and nearly all of it was wet or rotten. But on the boat deck, the drill holes mapped out problem areas and I probably only did 25-30% of the total area as the rest was dry core.

I know I need to do some of my side decks, just haven't worked up enough enthusiasm yet. In part because I don't think the screws will come out easy enough for the teak to be able to be re-used. And I really like my teak side decks. Steps are straightforward: remove teak, map out wet/damp core, cut off top GRP layer and then remove the core. The fun starts as soon as the teak is lifted - the bedding compound is sticky and gets everywhere....

[jleonard]

Originally Posted by Greatlaker221

What do you all think about assuming most of the core is wet, use a circular saw to cut at the outside edges of the core, lifting the teak and top layer of glass at once. This saves lots of labor. Remove/replace the core and glass over with 3-4 layers of 1708? Thoughts?

I think that is certainly worth a try. Worst case you still need to chisel out the core or attaching screws.
I would replace the core with exterior plywood, then glass over it. Use mat as the first layer as it will stick to the plywood better. Then use roving or the biaxial stuff, followed by mat to make a nice surface. Then vinylester gelcoat tinting it to the color of your choice and add nonskid. It will roll right on and look great.

[FF]

"But two layers of glass is the typical recommendation. By which I mean put on one layer with resin and let it cure, then put on the next layer."

BEWARE , any Polly resin that cures hard will have wax in it to achieve the cure.

This has to be sanded before the next coat/ layer of GRP is installed.

Resin is heavy with little strength , so laminating with NON wax resin will allow the most glass with just enough resin.When the first layer has gelled , the next can be laid up , that's how most hulls are built.

Then a layer of waxed resin can be laid on to cure , or just wait long enough with the sunshine to help cure it in a couple of days.

Epoxy would be first choice as repair resin, it will actually stick to wood or old GRP much better.

Epoxy works best too when it is not asked to stick to hardened epoxy .
Sanding to the glass works , but layer on layer after it begins to set is stronger and required no interlaminate sanding.

Epoxy will need a good scrub with strong soap after its hardened to remove the hardener.

[O C Diver]

Removed the teak from my back deck and then put two layers of biaxial cloth and polyester (fiberglass) resin down. The deck was a little too flexible before adding the fiberglass. The reason the two layers made such a difference is that the deck is not that large and it has a continuous curve from side to side and front to back. Had it been a flat surface, the 2 layers wouldn't have made as much of a difference.

Removing the teak

Ted

[windled]

I investigated this at great length when considering buying and refurbishing a WWII wooden mine sweeper that had been converted to a yacht. The answer I found was: do not glass over the wood. The biggest problem was that when a bit of moisture gets into the layer between your new glass topping and the deck glass below, you have a nightmare. So, bite the bullet and either replace the teak, or remove teak and glass over the deck. You'll have a better finish, less weight and have eliminated a huge future problem.

My 9.38 cents (inflation)

[TONTOROSS]

Originally Posted by jleonard

I think that is certainly worth a try. Worst case you still need to chisel out the core or attaching screws.
I would replace the core with exterior plywood, then glass over it. Use mat as the first layer as it will stick to the plywood better. Then use roving or the biaxial stuff, followed by mat to make a nice surface. Then vinylester gelcoat tinting it to the color of your choice and add nonskid. It will roll right on and look great.

When you refer to exterior plywood, are you refering to 1/2 or 3/4 green board?

[RT Firefly]

Greetings,
Mt. T. I think the reference is outdoor rated ply which has waterproof glue. Do NOT ever use the green or any other color/clear pressure treated ply/wood.