Re-deck

[Diverted Income]

I am currently re-decking a 24 foot Harris Flote-Bote. I used exterior plywood and double coated the top side with fiberglass resis ans well as edges and 3" around the perimeter on the bottom. Used a router on the edges so the sheets interlock and slid them together with urethane sealant in between the sheets. I plan to resin coat to heads of all the bolts before carpet. My question is should I be done with the plywood joints or should I lay fiberglass matting down and glass the deck pieces together? Would it eventually crack anyway and get water under the glass then?

 

[rrhodes]

Re: Re-deck

I would think more water would intrude from the bottom. Did you use exterior or Marine Grade plywood?

I would be concerned that sealing the plywood in resin would slow the drying process and even promote rotting.

 

[Diverted Income]

Re: Re-deck

From what I found the exterior and marine plywood both use the same glue, the difference being a lack of voids in the marine variety. this boat sits out uncovered all summer so i want to keep the water off the surface of the deck. the bottom is left open to breathe. Considerably more than the factories do.

 

[rrhodes]

Re: Re-deck

Pressure treated plywood is not suitable for marine use. The treatment of plywood with copper and arsenic compounds under pressure simply does not make the plywood waterproof, and worse, continuous exposure to water will leach the preservative chemicals from the pressure-treated wood.
Pressure treated plywood is ordinary, interior-grade plywood that has been chemically-treated, and it is often made with softer woods to enable the penetration of the wood treating chemicals, with no special care effected to eliminate all gaps or voids.

Marine grade plywood, on the other hand, is a different creature. Marine grade plywood is assembled gap and void-free in all layers and laminated together with special water-proof glue that holds the various layers together. When immersed, water has absolutely no effect on the glue or the strength of the lamination of marine grade plywood. Marine grade plywood will not commonly delaminate, bubble, buckle, or warp. Upon cutting marine grade plywood, no voids will be discovered on the cut edges. It is also usually constructed of harder woods such as Douglas Fir, or Western Larch.
Marine grade is a superior grade of plywood, and a substantially better product.

Not saying that the plywood you used won't work but it will not last nearly as long as Marine.

 

[Diverted Income]

Re: Re-deck

Yup that is right. That is why I didn't use treated plywood. I used exterior grade plywood CDX. It has the same glue as marine and doesnt have all the nasty chemicals of treated.

Back to my origianal question. Do you think it is a good idea to glass the decking together to form one integral deck or leave them sealed only with urethane caulk at sheet joints?

 

[5150abf]

Re: Re-deck

A correction, I was reading the tag on a bundle of marine ply at work and it is pressure treated with arsenic also where regular 3/4 is 5 ply, marine is normally 7 ply and I concur with the rest, one is made to use in a house and other is to deck a boat and is far supirior to anyhting else.

Regular CDX is made to be used in moist conditons where marine is made to be constantly wet.

As to your question, I would stop at the caulk as the deck will probably flex some so the glass would crack I think.

The deck on a toon is a structural part of the boat so make sure you through bolt it really well, the better you attach it the stronger the boat will be.

 

[Diverted Income]

Re: Re-deck

Good. That is what I was thinking too. As far as bolting goes, this time it will have all the bolts installed. The previous owner used about half the bolts. He also used treated ply and cheapo non marine carpet. It was re-decked in 2005 and it was already rotten. The cheap carpet kept the deck constantly wet. It didn't have a chance.

 

[DMAN1968]

Re: Re-deck

Hello,

Just a quick question, did you use polyester resin or epoxy resin? The reason I ask is that the epoxy resin is much more waterproof than the polyester variety and is used alot in wood boats. Make sure to seal all screws and bolts with the resin or you will just be allowing water to get into the wood and then not have a way out, leading to rot. Pre-drill all holes and coat that with unthickened resin until the wood will not soak up any more. If totally encapsulated in that way it will last a good while.

Leaving the bottom uncoated should be ok if it is a good exterior grade wood as the glue should be waterproof itself. Some water can penetrate the plywood but shouldn't make it past that first layer of glue. Not as good as marine ply...but sometimes you have to use what is available.

 

[Diverted Income]

Re: Re-deck

I did use polyester resin. I knew the epoxy was better but thought it has to be way better than the previous deck! I did pre-drill the holes and coated the holes. Also, after the bolts that will end up under the carpet were installed, I resined them in place too. Now I'm just letting the resin cure and will be ready for carpet in a day or two.

Had the resined sheets sitting out when it rained a couple days ago. Nothing but beads of water on them. Bottom was bone dry. Have 20 oz for-real-marine carpet to go on top of it and the fencing will be elevated too this time.

 

[DMAN1968]

Re: Re-deck

Epoxy is so much easier to work with than the polyester stuff...but also quite a bit more expensive. Don't think I could go back to the poly stuff after using the epoxy. but in any case, sounds like you have a pretty good handle on things...should work out fine. Let us know in any case so that the info can help others here.