Fiberglass over wooden deck

I have to replace the fiberglass on my wooden deck. It sees a fair amount of traffic and up to a dozen scuba tanks. I have no idea how thick the fiberglass that is on it is but it is cracked and lifting in most of the areas and needs to be replaced. I would like some opinions on how many layers I should put down. I have read that two layers of a 7.5oz cloth and polyester resin would be more than enough. Just wondering if any one has eny experience with fiberglass over wood for primary deck.

 

You will have to tell us how big the boat is, what sort of timber deck etc., for any useful answers mate.

 

When you say wood decks are you refering to plywood or wood planking over deck beams? You dont want to use polyester resin for sheathing wood of any type,use epoxy only.If the deck is plywood i would use dynel in epoxy,1 layer is enough,if its planked i would strip it back to the bare wood,epoxy and staple down a layer of 4mm plywood and then sheath that with dynel.
Steve.

 

Steve, He says he has SCUBA tanks on deck, one layer would be useless, it would be punched through first time out mate.

 

The Boat is a 34' Cape Islander. The type used for Lobster fishing on the East Coast. The wood floor is 1" planking on top of doubled up 2 x 6's as stringers every 16". This boat is very rugged there is no give in the floor.

Chris

 

OK, I would suggest that you will need 4x 300gsm of csm min, that will be a sturdy platform to work from, try laminating up that level and see how you feel about it, certainly will need a fair bit to drop steel/alloy tanks onto.

 

The way to cover a planked deck with glass is to begin with plywood over the decking planks. It need not be thick (1/4" ought to do), but that stable substrate will not "work" and so there will be less relative movement between the wood and the glass. What moves slightly will be the fasteners used to apply the plywood, which is fine.
Use epoxy also. It is well worth the expense. Polyester doesn't adhere very well, nor is it as waterproof. It is best used to join with more polyester, that's about it.
Glass schedules will vary depending on how much abuse it will need to take. Two layers of 8 or 10 oz is what I would put down, but see whast others have to say, as there are some who do this all the time.

 

Thanks for the info. You have me convinced on the epoxy. The plywood represents a bit of a challenge, but I think it might be worth it. Can you get a Marine grade 1/4" plywood? Or is regular plywood good enouogh since it will be sealed with epoxy? Know the name of a good fiberglass supply store?

 

The plywood is pretty much a requirement unfortunately as Alan points out. It's sort of like putting tile down in your house. You have to have a stable substrate under it or it'll crack.

I think 1/4" plywood is fine if you use Dynel, but you should up to 3/8" or 1/2" if using regular fabrics. Dynel is much more elastic then regular cloth and can handle some movement. Dynel is also a lot more abrasion resistance then regular fabrics (at least three times as much) but it doesn't cost much more, so it's a good investment. Best of all you'll only need a single layer of Dynel.

On the flip side of the coin (there's always a bad side) Dynel needs about 3 times as much resin to fully wet it out. Dynel can be easier to drape over compound curves, but it's often difficult to apply because it can float in the resin.

You can get everything here (http://boatbuildercentral.com/index.php) or you can look locally. Try fiberglassing supplies in the phone book.

 

Ok,after seeing the scantlings clearly you dont need anything for strength,just for taking the impact of banging around with scuba tanks,so since its just a big flat cockpit sole you may want to look at just bedding and screwing down some sheets of some kind of plastic sheet maybe 1/4" thick, id look for something with good uv resistance,reasonable dimensional stability and a molded in nonskid, there are many such products out there,the material cost might be more but the labor and maintainance will much less.
Steve.

 

PAR is the expert and his advise is always well heeded. But if you stop there I think you are treating the symptom not the root cause.

The real issue to be addressed (after repairing the existing damage) are the tanks themselves. Don't they make slip or glue-on open cylinders of rubber or synthetic to protect the bottom end of the tanks (and therefore anything they come in contact with)? You might also consider using workshop foam rubber interlocking floor tiles which are very cheap, can be removed easily, reversed when worn and will do a good job of protecting your deck while affording a comfortable non-skid surface. This will have the added advantage of offering protection to your expensive regulators and all other gear.

 

The basic problem with "laying" something down on the deck is unless it's sealed to the deck, moisture will get between it and the plastic or whatever covering and cause rot.

Protecting your equipment investment just makes good sense. Covers, tank booties, protective holders, etc., but decks with a lot of traffic (like dive boats) need a tough skin. It either has to be breathable/drainable or has to be literally married to the deck so nothing can get under it.

 

These folks have a lot of helpful information on using epoxy & polyester resin, handy tips, and products at very competitive prices along with a very quick reply tech service dept..........

http://www.fiberglasssite.com/servlet/StoreFront?gclid=CLfZ4-vBz5kCFeRM5QodbQMqKg

By the way, I'm in the process of removing a badly done deck on my Trojan Sea Raider. A previous owner thought it would be a great idea to cover the teak veneer with a single layer of fiberglass cloth and lap it over the rub rails. Yup, you guessed it, the cloth got as brittle as a potato chip and water migrated in when the rub rail, well, rubbed and broke the glass laminate, the wood got wet and is now a bit spongy in a couple of spots so my decision is whether to do a repair in the spongy areas,(which no doubt will get much larger as I get into it ) or to replace the gunwales and the bow deck entirely.

 

Good points PAR, a better idea than my first would be to use "Dri Dek" open grid tiles.
www.Dri-Dek.com

 

There is no question of the superiority of epoxy resin to bond sheathings to wood. There is also no question that if you use polyester on wood, you will eventually have a moisture ingress issue. Guess what happens next. Coupled with the need for mat, which has no strength and the amount of poly resin needed to produce a similarly dense and smooth surface (compared to an epoxy set sheathing), it's false economy to believe poly will save you anything. Just go into a boat yard and look at 20 year old or older boats and you'll get the picture.

The only poly sheathings I've seen last, were laid up so heavy that they need twice the amount of materials then if it was epoxy. What was saved in these cases? Certainly not weight.

Dri-Deck squares work well, but they should be removed from time to time and cleaned under. If not, grit and other abrasive materials will lodge in the grid and abate the deck below it. Fortunately they're very easy to move around.