New deck for deckboat

[BilDewey]

Hi guys, Long time no talk to. I've got a project I hope you can help with. I need to put a new floor/deck on a 23'deck boat because he old one is so rotten I fell through it. The floor/deck is rotten and so are most of the short bulkheads that support the floor/deck above the bottom of the hull. This boat sees extreme temp variations from 115 during the summer and 20's during the winter. I beleive the problem started when water left over from winter storage condensated during the heat and collected on the underside of the deck and couldn't escape.

I was thinking of using marine grade plywood for the deck and using foam sandwiched between two layers of glass for the bulkheads. Any thoughts on this? Could I use foam sandwiched for both the bulkheads and the deck? Whats the best way to attach the floor/deck to the bulkheads? Currently the bulkheads are 3/4 plywood standing on edge. The bottom of the bulkheads are glased into the bottom of the hull and the floor is through stapled to the top edge of the plywood (poor method and I don't want to do it the same way as before because that could have contributed too).

I'm going to use epoxy for all of the repairs for the superior strength and adhesion. I was leaning towards the foam for resistance to rot. What weight cloth and how many layers would you use?

Any help or suggesstions is appreciated.

Bill

[Techno]

I used 1/2" Divinylcell and 2 layers of 6oz. cloth on both sides. I think Klegcell is the same stuff different name. My floor is 4'x7' and weighs in about 20lbs. Also put ribs underneath since I don't have any frames to support it, an advantage you have.

You could use the foam for both the floor and frames. Might want to add a 3rd layerat least on the top surface, you don't need to worry about weight.
The easyest way is to lay the glass on the foam panels as they are and then cut them into the needed shapes. The panels ship 2'x4' so this might be a problem for your floor. You can tape them together no problem - its just going to be more panels for you.
I would put the frames in then put a thickend epoxy adhesive on them and lay the floor onto it. If you can tape them afterwards even better.
You could lay several panels down and lay the cloth over them at one time also. Just keep in mind the size you have to work on.

With the size your dealing with you could do a section with the glass tape on the bottom ready for the next panel, put some adhesive on the lip set the 2nd in and tape the top joint. 23' is long way to go with a single sheet!

I poured poly resin on the foam squeegeed it around layed the glass, poured squeegeed, layed, poured squeegeed. Goes pretty fast and is easy if you ignore the edges and just do the flat surface.
I clamped 2 panels together and filled the gap, then taped the seam with 2 more layers on each side. Took those 2 panels and joinded them together to finish the size.
I used polyester resin since I didn't see any advantage to epoxy in this situation. It was cheaper and it kicks off faster, as fast as you want just about. This would move your patio job along much faster.
Also added was a box in the floor for a custom cooler. If you need additional storage you could do the same.

Marine ply wood be faster and easier, should still seal it though. when joining, either don't use screws or drill holes and fill with epoxy. Use these plastic sockets for the screws. NO wood exposed no rot, or at least greatly reduced. The foam, glass and resin comes out to about the cost of marine ply. But you still need to seal the ply.

I stuck a chunk of the foam in a glass of water for a few months and it didn't absorb any water at all.
Also took some trimmings and set them out in the weather, nothing wrong yet.


I for some reason I get a magazine called deckboat party barge or what ever they're called. They advertise something I think is plastic that they use to build them. That might be an option too.

[Jeff_G]

glass in the new deck and ribs using cdx exterior building grade plywood. Marine plywood is NOT needed except where you need a beautiful finish or specialized use. Save the $$$$ coat it with West system or thinned poly on the bottom. If you use foam be aware you will be trapping water in every nook and cranny and will never be able to dry out the inside. Good air circulation is the key.

[BilDewey]

What do you mean by plastic sockets for screws? Are you talking about mollies?

I called my supplier here in San Diego and I can get Divinylcell in 4x8 sheets so that would make it easier. My cost on 1/2" foam is $75 and $100 for 3/4". That is for the 5lb hi density foam which is stronger. I can get marine plywood for $50 for a sheet of 1/2" and $65 for 3/4". Considering the cost savings, I think I'm going to use the marine grade plywood and epoxy for everything. I might be able to get away with using exterior CDX plywood for the deck, but I have a hard time justifying putting anything for a house in a boat. Even if it is a deck boat.

I think I'll use use the epoxy adhesive in conjunction with a few screws to make sure its good and tight. This is a friends boat, so I want it to be done right the first time.

:cool:

[Techno]

If you can get marine ply that cheap use it.
The sockets I was mentioning is. You drill a hole larger than the screw-2 ways
1: Fill it back up with thickened epoxy and drill and tap the plastic.
2: set the screw in a smaller pilot hole in the bottom of the large hole and fill the hole. Remove screw when epoxy is cured. put something on screw for mold release. Either way the screw is going into the epoxy not the wood. And it is strong. about 2-3 times the screws diameter for the hole.
I would also seal the holes in the deck for the screws by brushing some epoxy in them.
The basic idea is all the wood is sealed all by itself, it doesn't need sealant stuck on it anywhere.
You could also drive the screws in and later pull them back out and fill the holes.
The screws going through the deck into the ribs probably are only needed to clamp it down onto some thickened epoxy.
As you lay the deck down if you can glass it to an exposed rib that would be nice too, before you lay the next sheet down.

There is a difference between marine ply and all the others. There are no voids in a sheet of marine ply, or bark fillers. Look at the edge of any sheet of ply wood and you can see the diff.
If you can stand on a sheet of ply supported only by the distance the frames are apart this will give an idea of whether you need 1/2" or 3/4" being bonded to the frames is going to make it stiffer too.

[BilDewey]

Thanks Techno,
I think I've got enough to get started in the right direction. I may have another question or two once I get into it.

As far as the screws go, I'll probably drill, fill, redrill, and screw. I think a small test panel will be in order too. As far as tapping goes, I didn't know they made taps for ss wood screws.;) After the whole decj is installed, adhered and screwed, I'll probably finish it with one additional layer of cloth and resin to cover the screws and get a nice finished surface prior to carpet.

Bill