best way to fix a major hook?

Discussion in 'Fiberglass and Composite Boat Building' started by richofoz, Jun 12, 2013.

  1. richofoz
    Joined: Jul 2010
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    Location: Melbourne

    richofoz Junior Member

    I have an old 15ft glass boat I'm doing up
    (when I say doing up, i mean theres almost zero left of the original boat!)

    I have just flipped it to fair and re gel the bottom and have noticed a severe hook running from aprox midship to the transom.

    there's probably 12mm of hook in the deepest spot.
    (abeam/across the entire hull)

    I have a couple of ideas to fix it but would love to hear some suggestions from others.

    Don't hold back as I can swing a torture board all day long if need be!

    Just a side note, I will only be using vinylester resins and iso gelcoat...
    I have plenty of talc, cabosil, flock and milled fibers at my disposal.

    I also have enough 1200gsm s-glass triaxial to cover the entire area I need to repair if need be...

    all suggestions appreciated!

    Rich.
     
  2. richofoz
    Joined: Jul 2010
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    Location: Melbourne

    richofoz Junior Member

    I should quickly add I have plenty of stitched bi/tri e glass in different weights too, just thought I'd throw out the option of the s-glass to the pros!
     
  3. tunnels

    tunnels Previous Member

    What is the reason the hook is only in the aft end ??
    You would be better to push it out from inside . Is it just the keel ?? what about the panels each side of the keel ?? have you checked other places as well ??
    Any pictures to see what's there and the extent of it !! also what inside in that area !!:p
     
  4. richofoz
    Joined: Jul 2010
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    Location: Melbourne

    richofoz Junior Member

    the boat originally ran a 4 cylinder inboard connected to a jet!
    not sure if the hook is deliberate or a manufacture flaw...

    it now runs a pod and an outboard...

    i'll try and get a pic or two up soon.
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Most designs don't employ as hook, though some older, usually warped bottom shapes can. This is important to distinguish, as she may run bow high without it. In this vain, if the new engine setup has power tilt and trim, this is a moot point, because you can trim her down as required.

    I disagree in pushing down the hull from inside. If you have lots of time and are willing to install lots of internal bracing, then maybe you can go this route, but it'll be more trouble and weight then it's worth. 'Glass has a memory and will retain its shape if forced into it over a long period of time. Forcing this out of the laminate takes a similar amount of time or internal bracing to hold the new shape. To me, it's just simpler to accept what is and fill the hollows in and call it a day.

    You only have a 1/2" hook, so bulk up the low spots and drag out the board 'o pain and have at it. Use a structural filler mix with your fabrics to get most of the low spot(s) filled, then a light weight fairing compound, to feather it into surrounding areas on the bottom.

    One way to tell if the hook is intentional, is the chine will often (not always) have a similar hook too. Eyeball the chine and look for the hook. If it's straight, it's probably a poorly fitted trailer caused the hook (very common). If the chine does have a hook, you might want to try out the boat with the new setup first, before pissing off your elbows with the long board.
     
  6. tunnels

    tunnels Previous Member

    Hook could have been caused by the hole where the jet was not being pushed out before it was glassed over and filled in 12 mm is not to bad as long as its not all the way across the bottom . a big hollow will take quite a bit of filler to get it back out flat again. !! id the any sort of a keel on the outside or is it just a vee ?? doing the push out from the inside is not that difficult a couple of 6x2 on edge clamped to the gunnels and a hydraulic jack and its over in minutes then make and fit some internal stringers or what ever for the inside and replace what ever is there now with new ones well glassed over and that's about all there is to it ,almost !!
    The bottoms of smaller power boats are not really that ridged that's for sure and its usually quite easy to take out hollows or bumps once the framing inside has been relieved !!

    Hook in the bottom near the back can and will make the front of the boat hard work to raise even with a good power trim and the faster you go the harder it is to raise :p!!
     
  7. richofoz
    Joined: Jul 2010
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    Location: Melbourne

    richofoz Junior Member

    Yes Tunnels the hook is right across the hull and yes the boat doesn't respond to trim as well as it should.

    The boat has new stringer/foam/sole so its not getting pushed out from inside!
    Its also a lot thicker than most boats.

    It's a bit of a Frankenstein boat it has a keel till aprox mid ships then a plank that runs across the old jet intake whole and blends in to the bottom of the pod.

    I don't think this hook was intentional and with only 50hp pushing this rig I believe it will be more efficient and respond better to trim without the hook.
    Am I wrong?

    My plan is to rough fair it all out with vinylester/milled fiber bog to get the rough shape. Lay up 225 gsm chop then 1200gsm tri ax then another 225 just to sand to fair it a bit without eating in to the triax.

    Then fine fair the lot with VE mixed with cabosil/microspheres...

    Anything wrong with this aproach?
     
  8. tunnels

    tunnels Previous Member

    Still like to see some pictures of what you got !!
     
  9. RTM
    Joined: Jun 2013
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    Location: Central Florida

    RTM Junior Member

    Is this a flat bottom hull or a semi V or a deep V.?

    rich
     

  10. richofoz
    Joined: Jul 2010
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    Location: Melbourne

    richofoz Junior Member

    Shallow V.
    Haven't measure it but about 12 to 15 degrees...

    I'll drag the boat out of the shed today and get some pics.
    Finally got a day off with some sunshine!
     
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