Condition of the bottom hull

Discussion in 'Boat Design' started by blared, Dec 6, 2008.

  1. blared
    Joined: Aug 2005
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    blared ALFA

    Condition of the bottom hull


    For maximum speed the bottom should be as flat as possible in a fore aft direction (longitudinally) for approximately the last 5 feet (1.5m). For best speed and minimum spray the corner between the bottom and the transom should be sharp.

    The bottom is reffered to as having a " hook " ( also caused by not trailering or storing the boat with support directly under the transom ) if it is concave in the foe and aft direction. A hook causes more lift on the bottom near the transom and forces the bow to drop.
     
  2. messabout
    Joined: Jan 2006
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    messabout Senior Member

    Are we to presume that you are referring to a planing power boat? Also, are these declarative or interrogatory sentences? These are generalities that apply to a particulasr range of boat sizes. There are more than a few boats that are deliberately designed with a hook.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yep, I was wondering about this one too. Maybe I shouldn't assume there's a point. For what it's worth my, latest design has the pointy end towards the front of the boat.
     
  4. David55cobra
    Joined: Nov 2008
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    David55cobra Junior Member

    The boat in question is a powerboat - planing high speed hull (inboard/outboard 300hp )with what appears to be a slight hook just forward of the transom ( looks to be no more than 1/2 inch and extends forward no more than 3ft. The hull has another hook in the bottom about midships from not being supported properly - looks to be more in the range of 1 - 1 1/2 inch concave. Is getting this hull back in line something that sounds reasonable ?
     

  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Much depends on the design as Messabout has mentioned. The aft most hook may be intentional. At .5" depth it sounds about right, as does the length. A picture of the hull, with the design name being more useful, would be a great help.

    Yes, removing the midship hollow is a good idea and if the material has taken a "set", some filler and long board work will eliminate the issue. If the material can be jacked back in place (and stay there) this is an option. The approach can be construction type related. More info about the boat will be helpful.
     
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