Need some layup help for fiberglass boat.

Discussion in 'Fiberglass and Composite Boat Building' started by Jmooredesigns, Jan 20, 2013.

  1. Jmooredesigns
    Joined: Aug 2004
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    Jmooredesigns Junior Member

    I am laying up a 14ft specialty hull and The layup schedule is 1 1.5oz skin coat followed by 2 layers 1808 tiaxial cloth with mat backing. Both hull and sides.

    On the sides of the hull mold at the top there is a slight lip aprox 1/8th inch edge outword and then back up for another 1.5" where the deck and hull join that I cannot get the 1808 to lay into the Edge (groove). What should I do here? build up with CSM? Which will be a PITA to cut 1" strips to fill this area all the way down both sides of the hull.

    I have a couple hard sharp corners in the tunnels in the hull I need to round off as well and was wondering if using a filler material here is best?
     
  2. Eric Sponberg
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    Eric Sponberg Senior Member

    The easiest thing to do is make up a putty with polyester resin, Cab-O-Sil, and milled fiber, which is very finely ground glass fiber. Screed that onto the recess with a plastic spreader to form a slight "ramp" of sorts that the 1808 can lay against. This essentially fills the void that the 1808 otherwise leaves. It's the same principle as fillets put into the corners where bulkheads meet the hull and deck--you screed in the fillets and lay the tabbing over them.

    Good luck,

    Eric
     
  3. midnitmike
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    midnitmike Senior Member

    Don't you think 1708 biaxial would be a product better suited for this job?

    MM
     
  4. Eric Sponberg
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    Eric Sponberg Senior Member

    1708 will have the same problem not being able to fill the corner properly.

    Eric
     
  5. midnitmike
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    midnitmike Senior Member

    I'll agree with some reservations. A small feature like the OP is currently dealing with will either require a material change ie. matt+cloth or filler and 1808 or 1708. I am merely questioning the practicality of using triaxial as his laminate... suggesting instead that biaxial might be a better material choice overall.

    MM
     
  6. Eric Sponberg
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    Eric Sponberg Senior Member

    I think that depends on what the designer specified. We don't know anything about the boat, its structural arrangement or its design pedigree, so until Jmooredesigns asks, we don't need to answer.
     
  7. tunnels

    tunnels Previous Member

    Triaxles and biaaxle of the same weights are interesting !!! also the oriantation of the triaxle 0/45/45 or you could have 45/0/45 or 90 /45/45 and have seen 45/90/45 each one has its uses and so something to think about .
    Specially the placement in the boat topsides or hull bottom .so which one would you use and where ??? If the hull has strakes they need to be glassed and filled and glassed over . they cause weak places in the hull bottom and places where the hull panels bend and fatigue over time . have fixed lots strakes over the years where the glass layers have delaminated and cracked the gel and those lovely leaks sometimes from end to end !! :D
     
  8. Jmooredesigns
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    Jmooredesigns Junior Member

    Using the Triaxial because thats what we told would be best for the laminate. Not that Biaxial may not work though. Pricing seems to be very much a wash on the Triaxial and a similar Biaxial from our supplier.

    We are using Vectorply E-LTM-1808 0/90.

    The ridge is just to deep for the thick glass to go into it. And its probably because its such a small area. Will mix up some putty as suggested and that will fix the problem and wont be very thick at all. We now have 2 layers of 1.5oz CSM there plus the gelcoat now due to having to remove the 1808 that wouldnt confirm to the area anyway.


    You got me thinking about the biaxial vs triaxial now? what avantage or disadvantage is there?

    What brand of 1708 is everyone using? My suppler gave me this as a replacement biaxial OCT XM1808/1002/50 and its more expensive than the triaxial?

    A little more about the boat. Its a flat bottom with 2 reverse strakes that are 1" deep and 4" wide from the transom towards the bow aprox 3ft. The beam is aprox. 5ft and the depth of the hull is 15" The boat will have a all glass floor liner that will be sealed and foamed with 2lb foam that will be a big part of the structural strength of the hull once glassed in place. The boat has been being built for over 30 years and we bought them recently.

    I know why the weird strakes. well there is a design feature for this craft that allows it to not skid so much in turns because its flat bottomed and also allows it to be pushed or pulled off sand bars or mud flats in tidal waters.
     
  9. Eric Sponberg
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    Eric Sponberg Senior Member

    Of course, all that could come into consideration, and decisions for those materials depend on the geometry of the boat, its shape, and its internal structure--about which we know nothing, so it is pointless to speculate until specifically asked. A lot depends, too, on what the builder is used to using and what his suppliers can provide at a reasonable cost and delivery time. The boat is only 14' long, a pretty small vessel, so just about any material can be made to work.

    Whenever I design a new boat structure for a client, or if I am specifying a repair, I always try to spec out the materials that are a best fit for the job considering the boat's structure, the skill of the builders or repairers, and what is readily available. There are dozens of ways to build and repair boats, all of which work, so you chose the best match, all things considered.

    Eric
     

  10. Jmooredesigns
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    Jmooredesigns Junior Member

    Here is a photo of the hull with skin coat on. you can see the area on the lip that the glass will not conform to. you can also see the reverse strakes as I call them. Not sure there is a technical term for them actually. LOL

    I have strongly considered going down to a 10-12oz biaxial and just adding another layer. But the 1808 lays fine everywhere but the top lip and around the strakes which we wil fill for sure and round the edges off and put wide strips of 1808 over once they are rounded off for the material to lay on them.
     
    Last edited: Jan 24, 2013
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