Trim tabs

Discussion in 'Powerboats' started by 640 blazer, Mar 14, 2010.

  1. 640 blazer
    Joined: Oct 2008
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    Location: New Zealand

    640 blazer Junior Member

    Is it possible to have trim tabs on a boat that are too big ? Apart from the look and damage potential . Can trim tabs get to a size where they have a negitive affect or is bigger better .
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    They could be big enough to make the boat sink. Without getting to that extreme size, too big will create too much friction.
  3. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    not too helpfull gonzo .....if they re fixed and are more than about 3-4 deg down then they are too small..If they are electric then its quite acceptable to push them down 10 deg and get up onto the plane an then trim them out a bit like you would do with an outboard...its all a question of why you fitted them in the firstplace and are they effictive in curing the problem
  4. Willallison
    Joined: Oct 2001
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    Location: Australia

    Willallison Senior Member

    If the tabs are really too big, you can introduce dynamic instability problems in the form of 'bow steering'. Large tabs will normally need to be angled less to have the same trim effect as smaller ones, however. It's probably best not to stray too far from manuacturer recommendations unless you have good reason for doing so.

  5. Obsession
    Joined: Jan 2010
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    Location: Chicago, IL, USA

    Obsession Junior Member

    The largest "tabs per boat size" I've seen was a 24' lightweight boat mount the long 380 kplanes. These tabs were mounted parallel with the surface of the water rather than parallel with the bottom of the boat. Too large and you might increase the risk of tripping or hooking as a wave catches one of the tabs.
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