Stringer help?

Discussion in 'Boat Modification Journal' started by mdspoula, Jul 24, 2009.

  1. mdspoula

    mdspoula New Member

    Messages:
    297
    State:
    Kansas
    I need to replace the stringers in a 16' Dixie Devil tri hull that I just picked up cheap. I have experience with fiberglass and resin so that part is no problem. What I am wondering about is attaching to the hull. I have seen web videos that say you need a cushion underneath the stringer to prevent cracking. Also I want to know if I can use composite plastic decking for the stringer instead of wood. No rotting properties so I figured it would work the best for a new floor. Then I also thought about thicker plexiglass for the floor instead of wood which you have to seal on both sides. I know plexiglass can crack but I think If I put wood underneath the seat mounts I think that I would be alright. I am not 400 pounds and don't think I will have anyone ever on my boat over much 200 pounds. Plus it would be cool to pull up the carpet and see if any water is leaking in.
     
  2. kyelkhunter3006

    kyelkhunter3006 New Member

    Messages:
    1,192
    State:
    Ky
    Composite decking is WAY to heavy to use, not to mention that it lacks the lateral strength of regular plywood (it's very flexible until it's screwed down.) For what the composite costs, you can get wood, epoxy and glass both sides, and be way ahead in strength and it will be much llighter, meaning better performance from your boat.

    I don't think that plexiglass would last very long, It's either going to crack and break while you're walking on it, or due to the twisting of the hull as you ride. Besides, you'd still have to glue the carpet down, so you wouldn't be able to see through it anyway.

    Hopefully Mark J will chime in on this, he's the local boat guru, and he knows his stuff. There's also another site www.iboats.com that's got a lot of good info on boat resto.
     

  3. mdspoula

    mdspoula New Member

    Messages:
    297
    State:
    Kansas
    Yeah,
    I did some more checking and even thick plexiglas could possibly crack. I checked the composite decking at the store and one board probably weighed 40 pounds vs 10 pounds for regular decking. So I then found this other material that I want to try out called aztec. It is basically 3/4" trim for exterior doors but pretty strong and bends about the same as wood. I am probably going to butt the replacement pieces next to what is left of the original stringers. Then I will screw them to each other and put down a bead of adhesive underneath. I cut one to fit today and put a board across it and I think it will work pretty well. I think the combo mechanical bond and adhesive will work pretty good especially once I put a wood flooring on top.
    My dad is a plastics engineer and said Lexan would probably work for a floor but is $400 per sheet so I think I will use some plywood that came with the boat and is still in decent shape. I guess there is no good alternative for the fiberglass coating of wood yet. It just seems backwards to use wood which will rot when exposed to water.
     
  4. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    There is an alternative. Epoxy.
    If you use epoxy with your glass instead of the polyester or vinylester fiberglass resin it will encapsulate the wood and prevent water intrusion.

    Boat building epoxy has been specifically engineered to bond with wood.

    That is why there are so many rotted floors in boats. Manufacturers are cutting corners by using a product they already have on hand. A product not designed to do what they are demanding of it.
    All they have to do is use epoxy.
    They don't because it costs more and will disrupt the flow of the manufacturing process. Workers will have to be trained in how to use it.

    The consumer gets ripped off.

    You can use epoxy over fiberglass resins but you cant use fiberglass resins over epoxy.