Decking Materials

[{NW}BKUSA]

We are currently doing our 2nd refit on a 16ft sylvan alum. boat that we decked out and set up for bass fishing. Im sure after reading some of the post on this forum about the class of boats you build many will think it's a toy and not worth the effort. But the boat is mine and the time Ive spent fishing from it and working on it are priceless to me. In the first refit we used a 3/4 ext. grade plywood for the sheeting for the deck sealed with a poly and coated with a vynal floor covering for boats. As you may have guessed after 5 years its soaked rotting and weighs about 4x as it originaly did.
We are looking for a material to replace the main deck area something light weight ,strong and easy to work with a non-slip surface would be a plus. I would like to get away from useing wood at all if possable because it's poorly suited for the long cold wet winters and months of standing in the rain and will only need to be replaced a few years down the line.

I used a product manufactured in Florida, Seadek. It is a 3mm sheet of EVA foam with a self adhesive on the back. I covered my entire cockpit and front casting platform. Go to thier website....www.seadek.com

[{NW}BKUSA]

Thats some cool stuff easyer than wraping with floor vynal and we will most likely use it for step areas but I still need something to use as the deck it self ,still lookin for a better way to go other than wood

[PAR]

The reason your previous deck failed was the materials and techniques used. Exterior ply will work if not on a weather deck, topsides or bottom of a boat, leaving the bulkheads and cabin furniture as some of the remaining places you can get away with the lesser grades of ply. The reasons they are lesser grades becomes very obvious when asked to survive in a marine environment. Those reasons have most builders using quality marine grades in their projects. Planking materials, be it decking or bottom, are usually the best stock of it's kind on the vessel.

The reason it failed is rather simple, the ply wasn't up to grade, and it was sheathed with 'glass set in poly and this was covered in vinyl. This was a moisture trap in a big way, a death nail for any type of wood. Poly doesn't stick well to wood. Some will have you think it does, but the jury has been long in and it doesn't stick worth a damn. This lets in moisture, soaks the wood, then rot gets a foot hold. Because the wood can't breath because of the sheathing and the over coat of flooring material the ply had no chance.

The reason plywood is one of the leading decking materials is quite simple too. Pound for pound you will not find a better material, unless you can afford a bunch more effort and cost. It is stronger then steel and has qualities that are difficult to match, head to head with another product. It's easy to work width, is reasonably cheap, reasonably worked with tools most have in their tool box and can be found at the local lumber store.

If your deck was a marine grade ply, coated with epoxy, then sheathed in 'glass/mat of choice then painted or had another anti-slip surface put on, it would last much longer. That said, it too can fail if a breach in the coatings isn't handled in a timely fashion. In other words, if you put a screw into the decking to hold down something, then it better be well bedded or have it's fastener(s) bonded, or you can expect the same result.

There are a few materials that can be used for your deck, but I'd use a piece of 1/2" MDO over light framing all epoxyed in, with bonded fasteners and hardware pads. The MDO is rated marine under the APA standards and is a bit cheaper then BS1088 grade plywood. It also has a resin face on one or both sides which takes paint real well (that's what MDO was created for, sign painters) Without some sort of framing under the deck, you'll open up seams and joints with each step on the fore deck, that flexes the plywood. It needs be locked down with glue and fasteners on a support structure of some kind. Screws about the edges on the sheer will not be enough. A simple beam or two across the space should be all you need, for support.

You can try a product like "Star Board" but it doesn't hold fasteners well and must be through bolted, doesn't glue well, though can be welded (plastic welding) can't be painted and is heavy as sin. It makes a great cutting surface on a fish cleaning table, but I'd not use it for a deck.

Log onto the www.WeastSystem.com site and learn about epoxy, its uses and techniques for application in regard to holding fasteners, hardware, sheathing with cloth and mat, etc.

[JR-Shine]

The Seadek is really great - we sell it with free shipping

Rebuild the deck like PAR described (plywood sheathed in glass and coated both side with epoxy).


Joel
www.boatbuildercentral.com

[{NW}BKUSA]

nice site JR got a question for ya ....how much weight will the epoxy add to the deck ? and the expandable foam dose it capture water in its tiny bubbles it makes after it sets up...

[JR-Shine]

A couple coats of epoxy will add very little weight (just roll or brush it on). I would guess around 1/2 oz per square foot - nothing to consider.

The 2 part expanding flotation foam is closed cell.

[{NW}BKUSA]

Hey JR we where thinking can a sand finish be added for the final coat of epoxy ?

[JR-Shine]

I guess you mean for non-skid? Sure, but you will need to paint the epoxy to protect it from UV - so just add the sand (or non-skid) to the paint. Thats how is normally done anyway.

Joel

[drs3317]

This procedure and MDO for working sound good. Would this be a good choice for a new cockpit sole in my 31' sedan? I wasn't clear in understanding how to securely attach it to my support framing. Also I want to replace the support framing. Is pressure treated 2x lumber the best choice for this and should it be glassed or epoxied over before decking over?
Thanks

[{NW}BKUSA]

So if I glass the ply over to remove a seam cant I just add the pigment to resin to add color? instead of painting I thought fiberglass resin was UV protected. On your site epoxy looks like same thing you would use to fiber glass yes/no?........... Sorry to sound stupid but never used this treatment before ......got the idea from your site JR while lookin at the how to pics I could join 2 panels together w/ glass cloth then epoxy/resin the seam away to remove leak spot .....after do 2-4 more coats on surface to smooth the finish then add sand to traction areas.......so it will still need to be painted after? if so what is pigment for???

[PAR]

DRS3317, pressure treated lumber from LowesDepot isn't very good lumber. It's full of splits, checks, knots, pith and other unwanted things. The sole support structure should be similar to what was there, if not better. I'm not sure what boat you have, but white oak is typical as is Doug fir, but clear, knot free, straight grained stuff, not the junk you can buy at the big box stores. It can be 'glassed, CPES'd, painted or combination of, your choice. If this is a show boat or an investment, then only the original construction materials and techniques will maintain the value of the yacht. If this is a family boat (you intend to keep her for a long time, and not interested in max resale value) then other more durable methods can be used on her.

Fasteners that may live in wet or moist wood (like the bilge area) should be bonded. This can stave off rot for a long time and increase the pull out ability dramatically. Log onto www.westsystem.com for more details on how to work with epoxy.

{NW}BKUSA, using pigment in epoxy or poly is for the last coat, in an effort to match something or provide a clean base or other reason. It isn't generally necessary. Epoxy isn't UV resistant and must be topcoated with something to keep the sun from destroying it, paint is typical, though there are other coatings and methods.

You're becoming confused between epoxy resin and polyester resin, don't. They are very different, though have similar qualities in some regards. Both polyester and epoxy are used in 'glass work. Epoxy is the only thing that works on wood well. Poly doesn't stick and it will delaminate pretty quickly.

Plywood seams butt joined with cloth set in epoxy works rather well and will seal a joint. Again, log onto the www.westsystem.com site and pick up their free product use and repair booklets. They are full of the techniques used including fastener bonding, talked about earlier.

Sand is usually added to the paint (which is the UV protection) not the epoxy. Follow the instructions from the epoxy manufactures and you'll do fine. You already know what happens if it's not correct, so get the booklets or other info from other manufactures and practice a little before you dump a quart of resin on the deck and start spreading it around. It's not hard, but does require you follow the rules and use good technique, if you want good results.

[drs3317]

I've been reading most your posts on decking and now have a better understanding of what I'm doing and also sent for West system booklet. My cockpit project is a '81 Sea Ray 31' Vanguard Sedabridge. The previous owner neglected her and left her setting dry for the past several years. The sole had been removed and some support members replaced with junk which has rotted. I do plan using MDO for the decking epoxy all sides, mat galss on top and painted, correct? The support members will be doug. fur but need to know should they be epoxyed and galssed or just painted? What is best? Are deck support plans showing layout available from sea ray or another source? Thanks for all your advise.

[drs3317]

Almost forgot to ask; The support members that are there were connected to each other using aluminum angle and stainless steel screws. Is this correct or is there a better way? Thanks, Danny

[JR-Shine]

I would epoxy the support members to the floor - no fasteners. Use some silica or wood flour to make a glue. The less screws you have going into the wood the less chance of moister getting in.

That West booklet you have should show how to bond a piece of wood stock using epoxy glue.

Joel