Newby with Alloy Pontoon

Discussion in 'Powerboats' started by Kiwi Boy, May 29, 2011.

  1. Kiwi Boy
    Joined: May 2011
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Auckland

    Kiwi Boy New Member

    Hi guys,

    Got my first boat and want to get her going as best I can. She is a 4m alloy pontoon and has some dents underneath before the transom. Some dents are the size of a hand but one dent is 1 by 2 feet. I would push them out if there wasn't a floodable bilge, so I can’t get to the inside of the dent. Any ideas ?.

    I was thinking I might be able to epoxy some angle to the bottom and pull the angle and dent out ?. Or could I cut a round hole in the floor above the dent and when I am finished pushing out the dents, put a round hatch in the floor ?.

    I am concerned that the big dent is making the hull inefficient in both displacement and planing modes.

    Any help and advice is very much appreciated.

    :)
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The dents are increasing your drag, but you probably have enough engine to over come this. Okay, you might lose a few MPH at the top end and maybe slower to get up on plane, but it also might be something to live with.

    This said, popping out a dent isn't especially hard, even if you don't have access from the other side. The usual course is to use a dent puller, which looks just like a slide hammer, except it has a screw tip instead of a hook. Drill holes and pull the dent out a little at a time. Some like to work in a spiral pattern from the center out, while others use the "sneak up on it" approach and work the perimeter inward to the center. A lot depends on the shape of the dent. Once you have the dent mostly pulled up, use a hammer to smooth things out, but at this point you've probably stretched the aluminum pretty good, so you may want to employ a "shrinking" hammer. Which will help "unstretch" the metal. In lue of a stretching hammer, you can just be grateful for the reduced depression and fill the remaining depressions. I'd weld up the holes personally, but many don't bother, just using 'glass under the fairing putty to seal things up.

    Another option is to weld on little lengths of skinny bar stock in the dent. They have a tool specifically made for this, but you could tack on 75 to 100 mm lengths of 1.5 mm stock. Again the slide hammer is employed, but this time without the holes. You tug on each until you've pulled the dent out as best as possible. The closer the spacing the more precise you can be.
     
  3. Kiwi Boy
    Joined: May 2011
    Posts: 2
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    Location: Auckland

    Kiwi Boy New Member

    Thanks Par,

    some valuable advice there. I will do the dent puller method and then epoxy some layers of glass to the underside as smooth as I can to minimise the filler on the bottom. Winter over here now and the fish are not as plentiful, so I might start getting ready soon.

    Cheers
     
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