Dealing with Ice on a fiberglass boat

Discussion in 'Boat Design' started by comfisherman, Jun 25, 2021.

  1. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    Not big chunks of ice, not trying to reinvent the ice breaker here.

    We have some weird situations arise where bays with really high fresh water will freeze to a thin skin that sits barely below the surface of the water. I've hit it a couple times every few years on my metal boats, but will be all fiberglass this year. A neighbor just went back in after extensive repairs, he had nosed in to a bay with what he thought was 1/4 or maybe less skin of ice. Said he didn't think much of it until the bilge alarms went off..... it did a number on a few spots for sure. On the metal boat it would chip paint, but the glass seems to erode pretty quick.

    While the best solution is avoidance, would you?

    Thicken substantially the waterline leading edge of the boat?
    Try and clad some kind of stainless with thru bolts around the waterline belt area?
    Maybe give something like uhmw a try in a similar vein?

    Old wood boats in the area used to do iron bark for a sacrificial layer, kinda might need to re visit the idea.
     
  2. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Metal keel, slow waaayy down.

    I was breaking ice one morning in November last year, but 1/2" with an aluminum skiff.
     
  3. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    I have a 1 inch keel iron but it's only 2 inches wide. My one experience with glass and ice was a few hundred yards and the boat was tanked down so the anchor guard got a bit of a polish, and the gel coat got some chips.

    Speed would probably be the big one, on a metal boat you can hear the noise.
     
  4. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    Clad with steel, uhmw or wood. If uhmw pay attention to the correct grade, they are not created equal, even colour matters.
    To attach I would use thick continuous fiberglass strips on the inside, glued to the hull and tapped. Use a slightly shorter machine screw and cap the hole with thickened resin and a thin fiberglass plate. Alternatively you can drill blind holes and tap them, or use threaded inserts, but that's more tedious. The ideea is to avoid sealants and trough holes, those can leak.
     
  5. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    On my uhmw guard rails I've thru bolted with 316 cap screws and sealant. Could probably thicken and drill and tap as well, the bow is certainly thick enough. Mostly worried about the flat broad spots mid bow.
     
  6. Alik
    Joined: Jul 2003
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    Location: Thailand

    Alik Senior Member

    Lloyd and Russian Maritime Register used to have rules for ice reinforcement, for composite boats. These are no longer in the acting rules, to my knowledge, but if one looks at Rules early 2000's can find them.
     

  7. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    That would be interesting to see. I'll try and drum up some old references.

    The eastern canadians used to do a lot of ice prep on some of the big novis from the late 90s and early 2000s. Think they just went really thick and did seasonal repairs.
     
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