fiberglass riverboat

Discussion in 'Boat Design' started by SWIFTWATER KID, Oct 8, 2016.

  1. SWIFTWATER KID
    Joined: Oct 2016
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    Location: alaska

    SWIFTWATER KID Junior Member

    Am on a new path away from welded Alum to hand laid glass....Run 30/40 hp outboard jets over a 100 miles in Alaskan rivers where we mangle the jet foot and impellers hitting bottom..... (need light n' tuff)
    built tack n' tape over ply some years back......close but need lighter hull....
    1. am curious about stripping in hull with 6" s-glass tape in a 45degree crisscross X manner such as a cold molded wood hull.....an ol' timer explained about the stretch and compression design of cold mold.....so has kinda stuck with me.
    using VE and silicon bag for 18 foot sled.....as in the past will use Kevlar on impact zones and carbon for stiffeners where needed..... would of coarse us fabrics and weaves to build up and get the desired strength vs weight.......
    2. any advantage to curing hull in a kiln ? lotta work but if it is a true increase in the finished hull am open to start building such......
    3 am using a 3/8 UHMW skid on the bottom (full length) as this truly is the only way a glass boat will become anything but a "disposable " river boat in AK....thanx boys.......am expecting to hear Im nuts.....but ex-wife conditioned me for what's coming......let fly........
     
  2. ondarvr
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    ondarvr Senior Member

    You will probably be better off with aluminum, its light, can take a beating, plus low in cost.
     
  3. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    If you ever touch ice (which I suspect you do), aluminium will still be your best bet. Glass FRP would be lighter and better thermally, but would need pretty constant 'touching up' if you keep scraping the bottom. It (FRP) does have the advantage of easier compound curvature, though of course you may 'roll' alumuminum sheet. Semi replaceable skids etc may help minimise any damage to a glass structure underneath, but ice is unpredictable and can pierce even quite heavy laminate if your unlucky.
     
  4. ondarvr
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    ondarvr Senior Member

    Aluminum tends to be lighter than fiberglass in this type of application.
     
  5. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Not really sure as changing to a glass hull will stop you from hitting the bottom and ripping off the foot and damaging the impellor
    Do you use a tunnel ahead of the jet?
     
  6. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    Sounds like more HP is needed as 40 is not enough for an 18 footer.

    Or go with a smaller aluminum boat
     
  7. ElGringo
    Joined: Mar 2014
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    Location: Amarillo Texas

    ElGringo Senior Member

    Do you plan to drive it like a Sprint Boat? If so I don't think a glass boat will hold up, better start thinking Carbon Fiber, or staying with aluminum.
     
  8. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Carbon fiber doesn't hold up well to that kind of abuse, glass does better.
     
  9. ElGringo
    Joined: Mar 2014
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    ElGringo Senior Member

    Would that be because it is more flexible? Would Kevlar work better? How about that stuff that PAR has mentioned, I think it is named Zynole, Xynole, or something close.
     
  10. ondarvr
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    ondarvr Senior Member

    Yes, carbon is too stiff. Kevlar could be used in few places, but for most marine applications its mostly hype.

    There's as reason 99.9% of jet boats are made out of aluminum
     
  11. SWIFTWATER KID
    Joined: Oct 2016
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    Location: alaska

    SWIFTWATER KID Junior Member

    thanks guys for your replies, but we kinda missed the target....Am not suffering with Alum vs. Glass question.....have welded an sold a dozen boats out of my shop.....have repaired enough alum boats to make me puke at the thought of another.....(AM DONE WITH ALUMINUM).....
    ASK YOURSELF THIS:
    Fibergalss
    You are 300 miles from nowhere and you've just peeled you hull on a rock.
    With some resin and some cloth you can be good as new by morning.....
    Aluminum
    With flattened soup cans and epoxy this gets me floating....but am not going anywhere but closer to the truck.....(forgot to pack a generator an wire feed)

    Keep in mind....am using a UHMW skid.....the question of glass, Alum, wood or cardboard becomes moot..... The UHMW is the shield.....

    Am really only interested in my design idea of 45 degree crisscross pattern of 6" s-glass tape in building a lite strong hull.....
     
  12. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Well if you want to go that route, forget about about the crisscross pattern and just buy 2400 biax S glass, or better yet triax, that and epoxy and it will be strong. For best results it should be post cured, this will increase the strength a good deal.

    A friend of mine makes glass jet boats, they work well, but they don't sell as well as his glass driftboats.
     
  13. ElGringo
    Joined: Mar 2014
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    ElGringo Senior Member

    Kid, I spent 22 years at Bell Helicopter, 3 of it in material Bonding, and 10 of it in Tooling. I did a lot of composite tooling. The prints on some of the molds we made called for the fabric, sometimes glass, and sometimes carbon fiber to be laid 1st layer straight, 2nd at 45, 3rd the other 45, and the 4th at 90. BUT, I was always told by Engineering that it was to keep the mold from warping. I don't think they ever mentioned it being stronger. Some of the panels had one side made from Kevlar, some from Carbon Fiber, and the other side made from Glass with the centers being aluminum honeycomb. That has been a very long time ago and things change, so it may be different now.
     
  14. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    The big problem is getting it lighter then aluminum,it will cost 4 times more.Matching the toughness will be a challenge.
     

  15. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    How about a layer of sheet titanium on the bottom with fiberglass on the
    sides.
     
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