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Plastic board stringers?

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  • Plastic board stringers?

    I have found a new product called plastic board that is made out of recycled materials. I am thinking about using them for stringers in my boat. My question is; since their made from plastic materials they won't rot but would I still have to glass them in? Has anyone tried this? I was thinking of bedding them with PL Premium and not glassing them.


  • #2
    Re: Plastic board stringers?

    hi welcome to i boats.....


    the stregnth isnt from the stringer, its from the glass

    if you use that method you will have very little stregnth and your hull will be prone to flex
    The Hull Extension Thread
    great info on all aspects on boat building with detailed information.

    http://forums.iboats.com/showthread.php?t=234392

    IN MEMORY OF Our friend SpinnerBait_Nut LESTER WRIGHT July 31, 1953 - Nov 26, 2008 RIP

    IN MEMORY OF Our friend Tashasdaddy Robert (bob) Griffis. October 27, 1948
    November 29 2010 RIP

    Comment



    • #3
      Re: Plastic board stringers?

      Thanks. I didn't think I could get away with that. Another question. If I dig the rotten boards out but leave the glass sides and laminate the boards plus fill in the voids with PL premium would that work? Some of my glass sides are still good but the caps are all gone.

      Comment



      • #4
        Re: Plastic board stringers?

        Use the composite, and fill the space with epoxy and roven, stronger than before.

        (Oops, stepping on your toes today)

        fiberglass has been known to work. snicker

        Comment



        • #5
          Re: Plastic board stringers?

          Depends on if it's composite board or plastic board... the latter has a greasy feel to it, and is made up of polyethylene similar to garbage bags. Not much will stick to it, including epoxy. It's also not really stiff enough to use for stringers. Most of the strength of the stringer comes from the glass, or rather from the shape the glass makes around its form, but the material the stringers are made from also adds stiffness. The plastic board actually bends under its own weight.

          Composite board can work well for boat work, but it's usually more expensive than plywood. I suspect he's talking about the recycled plastic board.


          Also, I suggest not trying to get by on the quick and easy... don't just dig out the old wood and lay in new stringers gummed in with PL... take out the old wood and glass, grind clean, then bed in new stringers and glass.

          Trying to take shortcuts is possible, but you usually won't end up with a result you like. Get used to the idea now that you have to do it the hard way, and it'll be more enjoyable in the long run for you....

          Erik
          Sea Ray SRV-210 - Winter refit
          75-85 foot displacement hull trawler - gleam in my eye

          Comment



          • #6
            Re: Plastic board stringers?

            Yes, I am talking about plastic ply-board which is made out of recycled plastic. It is tougher but more flexible than wood. I figured that if I laminated 2 sheets together for 1 stringer that it should be strong enough to hold the floor and hull. I am not trying to take shortcuts I just don't want to reconstruct the whole floor again while I own it. Its obvious that using wood may not be the best product for this application because of water damage and rot. As for fiberglassing it that is fine I was only wondering because I have read about people just reusing the glass sides all ready in place.

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            • #7
              Re: Plastic board stringers?

              You're having the same thoughts that hundreds of other folks here have. It sucks to put wood back into a hull when it's rotted, but it really is the best product for the job unless you spend $$$. You can buy some of the foam core composite stringers if you're planning on keeping the boat for 30-40 years if you want. They do sell 'em, and they work nice, but there's no cheap way out.

              Other things people have thought of using for this job are plastic deck boards from outdoor decks, expensive exotic woods that don't rot, metal structural elements and girders, and even solid fiberglass.

              But the reason the wood in your boat rotted wasn't because wood sucks at this job, it's because the boat wasn't constructed properly or maintained properly, and the wood got wet. A boat should be built so the wood always stays dry.

              If you build it back the right way, take the time to do it right, and maintain it once done the wood will outlast the time you own the boat very easily.

              Probably the best reason to use similar materials to the original in a boat is that the original designer expected you to... if a boat needed a certain flexibility and stiffness in a spot, he chose materials that gave that. Using something else with different properties is a gamble if you don't know what you're doing.

              Plus if you use the same materials everyone else here uses, you can follow the examples and tutorials posted here closely and come out with very good results, even if it's your first time.

              Erik
              Sea Ray SRV-210 - Winter refit
              75-85 foot displacement hull trawler - gleam in my eye

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              • #8
                Re: Plastic board stringers?

                when I said composite, I mean cement board. I just threw it in mine for an afterthought.
                You have glassed sides like mine. The glass is the stringer, anything else is our over-kill.

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                • #9
                  Re: Plastic board stringers?

                  Just so you all know my boat is a 1969 14" glastron.

                  Comment



                  • #10
                    Re: Plastic board stringers?

                    Thanks for all of the advice but we are going to go ahead and work with the plastic ply board anyway. I only paid $150 for the boat and we are hoping that our fix stands up at least for this year. I'll keep you all informed of the progress and post photos. We are still brainstorming on the whole process but we think that we can make it work.

                    Comment



                    • #11
                      Re: Plastic board stringers?

                      It all depends. How long do you plan to keep the boat? Couple of years and sell/upgrade? You can do whatever you want. You can go with a product Seacast has that you can pour in the old fiberglass forms left after the wood is taken out and then glass over the top ( they have a tutorial on the site ), but again, Erikgreen has the right idea. You don't have to go crazy, you just have to go smart. Engineer into the boat what the manufacturing process left out....the details.

                      BTW, I used that plastic board for the bunks on my trailer. It works fine, but I had a small tab sticking out back and used it as a boarding step to get into my boat, it broke under my weight ( 200lbs ) right where it was bolted to the support.
                      my thread here,My Shareproject page,Part 1,Part 2,Part 3,Part 4
                      Official Tri Hull Club thread

                      Comment



                      • #12
                        Re: Plastic board stringers?

                        Originally posted by Coors View Post
                        Use the composite, and fill the space with epoxy and roven, stronger than before.

                        (Oops, stepping on your toes today)

                        fiberglass has been known to work. snicker
                        cant find the thread... but i thought i actually told someone to use poly ?

                        The Hull Extension Thread
                        great info on all aspects on boat building with detailed information.

                        http://forums.iboats.com/showthread.php?t=234392

                        IN MEMORY OF Our friend SpinnerBait_Nut LESTER WRIGHT July 31, 1953 - Nov 26, 2008 RIP

                        IN MEMORY OF Our friend Tashasdaddy Robert (bob) Griffis. October 27, 1948
                        November 29 2010 RIP

                        Comment



                        • #13
                          Re: Plastic board stringers?

                          When you craft was constructed builders used timber stringers because it was cheap and readily available, because the timber provided some strength and flexibility it was considered a good option.

                          However, poly resins are far from waterproof in the long term and they do not stick to timer very well with the passing of time.

                          This combination has lead us all to replacing ribs and stringers as well as other timber glassed items in boats.

                          Modern boats only have foam stringers with extra glass to compensate for the lack of stiffness in the foam. Engineering and practicality have lead to well rounded profiles, this gives better strength and makes layup easier.

                          Also note, epoxy will bond stronger to the old poly resins and is more water resistant.

                          If you have have not already purchased your stringers I would consider using a closed cell foam and more glass, even the water got inside it would do no damage.

                          Avagoodweekend......

                          Comment



                          • #14
                            Re: Plastic board stringers?

                            Okay, here we go again. I am not just going to put the plastic board and thats it. I am going sandwich the old stringers with the (they will also be adhered to the bottom of the boat) plastic ply-board, then I will glass up the sides of it and fill in the middle with resin and cap off! Have any of you glassed the sides of the plastic ply-board? I read the specs on it and its states that you can use adhesives with this material. I thought that encasing it with fiberglass was the most important deal and should give the boards plenty of strength?

                            Comment



                            • #15
                              Re: Plastic board stringers?

                              I think with them up on edge they will be strong enough, especially when glassed in. But it's my opinion that you should try to match the original materials as closely as possible unless you really know what you're doing. I say this because sometimes when you replace a structural element with something much stiffer or stronger than the original it creates stress or strain in other parts. In other words, it could cause areas to fail that otherwise wouldn't.

                              For example, let's say you hit a stump and it rips your trolling motor off its mounts. You go back and rebuild/reinforce your deck where the motor mounts. The next time you hit a stump, it rips a section of your deck up (or wrecks your trolling motor shaft) instead of just ripping the motor mount up again.

                              That's just my $.02.
                              Crosby Sled, '69 Evinrude 33HP Ski-Twin [Restoration Thread]

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