trax for stringers

[johnbell47]

I have been reading the debate concerning ply versus dimension lumber for stringers. Has anyone tried the composite decking material home depot sells? There are several trade names, most common being TRAX. The tech specs indicate that the stuff would be strong enoug in compression, shear and tension for this use, and it does'nt rot. Weight is comparable. I am doing a Grady White and am about at this stage. I don't know about how it saws, etc. Anybody got any experience?

 

[ondarvr]

Re: trax for stringers

The problem with almost all of these type products is they are heavy, weak and high in cost, plus (like Trex) many are made from wood products and recycled plastic. The plasic used is not compatible with resin and the wood molds and rots, so there's not much of an upside. There are PVC boards that are lighter and some resins will stick to them better, so they could be an option, they still don't offer much strength though, so the fiberglass laminate needs to be made stronger (thicker) to allow for it.

What you end up with is a somewhat heavy core that is high in cost and provides nothing but a shape to glass over. It won't rot (some can) but you could do the same thing with wood for less weight and cost, plus until it rots away in 20 years or so, wood will add a great deal of strength.

Almost anything can be used as a core for a stringer if all you're looking for is a shape, which is what a Trex type product would be, cardboard, plastic pipe, foam, wood or they can be pre-molded and hollow.

 

[Bob_VT]

Re: trax for stringers

I asked the same question years ago..... and Crab Bait (have not seen him here in years) had built some of the nicest project boats. I considered him to be a real mentor and he was absolute against Trax for marine applications. He suggested to spend money properly and go with epoxy for boat building (not poly-resin).


Quote by Crab Bait from the 2002 Archives
"i sure would hate to be the first one to try... they are heavy & pricy for sure.. i do know that the 'deck subsitutes' are NOT for structure.. only for deck boards where they are supported an layed on joist not far apart.. <br /><br />i'm sure not far off there will be, tho."--------------------------------------------------------------------------------

 

[tashasdaddy]

Re: trax for stringers

i agree with crab bait.

 

[johnbell47]

Re: trax for stringers

For the sake of argument, nothing else, the tech specs indicate adequite strength for this application. As for cost, the cost of stringer repair is in the labor, not the parts. If you worry about weight, how come a mercruiser exhaust manifold weighs soo damn much. Boy I can't believe how much weight these motors weigh and still float. lol. I only use epoxy, polyester stinks too much, breaks out my skin when i sand, etc. Course I am a canoe builder, strength, lightness count. I am getting in to the powerboat thing, cause I absolutely love barrelback chris crafts and old rivas. I am using the Grady fiberglass bottom covered with heart red cedar which i cut off my farm. This has only got one pointy end so it can't be that hard. thanks for the talk!

 

[ondarvr]

Re: trax for stringers

Unless something has changed recently all the info these companies supply with their composite decking says do not use it for structural purposes. It also says it needs to be supported much better than wood, as it won't span much of a gap without sagging or failing. The deck boards on my house are PVC and I did a great deal of research on composite decking before choosing the product I bought. The recycled plastic, mostly milk jugs and the like (Polyethelene), are not UV resistant and have a very low tolerance for heat, but the main problem is it's low strength and nothing sticks to it. Then you add old wood, or wood that couldn't be used for anything else, which is just the product you're trying to get away from in the stringer. The UV and heat issue aren't a problem in a stringer, but the low strength, nothing sticking to it and then having unknown scrap wood in it is. I've seen test results with epoxy sticking to TREX, but it's sticking to the wood and possibly other unknown stuff in it, not the plastic, so when the wood rots (just like the wood you're taking out) there is no bond.

As for the weight of a Mercruiser manifold and other related heavy items on boats, sometimes there's just no cost effective alternative.

 

[Chris1956]

Re: trax for stringers

Composite decking had very little strength. Deck support systems (joists and girders) are made from pressure treated dimentional lumber since it has the high strength and rot-resistance needed for decks.

BTW - I still prefer PT Dimentional lumber for stringer and frame applications in a boat. it must be dried well to absorb the resin (poly or epoxy), and covered in glass fabric of some kind to protect it from water damage. Plywood will delaminate when it gets wet, which is what happens in a lot of boat structures. My '88 seaRay had a scribed, 3/4" plywood keel stapled to the underside of the ski well floor. Some water got in there over the years, and delaminated it. The keel of the boat collapsed one day when I had it on blocks.

 

[contractorguy]

Re: trax for stringers

The keel of the boat collapsed one day when I had it on blocks.

Ouch!... Got any pictures??

 

[johnbell47]

Re: trax for stringers

O.K. I am convinced, thanks! Now I'm thinking bois de arc wood. I've seen fence posts over a 100 years old still being used. I'm kidding, it's too hard to work with in larger parts, i did use it for the stems on one canoe though. Guess I'll go with lumber. As you say all of the ply I took out was thouroughly de lamed.