Transom Angle

Discussion in 'Powerboats' started by smjmitchell, Aug 31, 2015.

  1. smjmitchell
    Joined: Jan 2006
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    smjmitchell Junior Member


    In looking at a range of smaller powerboats that are powered by outboards, I notice that there is some variation in the angle of the transom to the vertical.

    What considerations are there in selecting the transom angle ? Is there any rules of thumb that apply ? Does the transom angle have any effect on boat handling or stability ?


  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    If the boat is small enough to only use outboards without power trim, 13 degrees of rake is about right, but if it might use an engine with trim, 16-17 degrees is a better choice, reason being that you will get more ability to trim the motor in for better take-offs with heavy loads. Naturally, you would not leave it trimmed right down once underway, so you don't really use that additional angle with a non-trimmed engine, as you can't alter it underway. It won't make any appreciable difference to handling or stability, except a 13 degree transom won't get the full value out of a hydraulically trimmed engine. What boats are you looking at ?
  3. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    The manufacturer of your outboard should give specs for best transom angle. I know Honda does.

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

    Most modern designs will use 12 to 15 degrees of transom rake, which works with most outboards. Power tilt and trim can be shimmed for better "bite" off the line, but generally this isn't necessary, unless the boat is heavy for its size/length.
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