Interceptors vs Tabs

Discussion in 'Powerboats' started by Willallison, Sep 8, 2009.

  1. rbrooks
    Joined: Jun 2009
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    Location: Washington NC

    rbrooks Junior Member

    interceptors

    We use the QL's on all our 32' boats they work well at speed with less efficiency loss than the tabs. However, at low speeds their performance does suffer. They will work great at 20 knots but lose effectiveness on our boat at 13-14 knots.
     
  2. tom28571
    Joined: Dec 2001
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    Location: Oriental, NC

    tom28571 Senior Member

    Are you speaking of Fountains?
     
  3. rbrooks
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    rbrooks Junior Member

    No, These QL's are on the Eastport 32 You can see the boat at www.brooksboatworks.com. However I have had much experience with the Fountains earlier in my carreer
     
  4. tom28571
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    Location: Oriental, NC

    tom28571 Senior Member

    Very nice Mr Brooks,

    It looks like you don't carry the topsides tumblehome well forward of the sheer break as many NC builders do. I prefer the way you do it, if I am seeing the rendering correctly.
     
  5. Willallison
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    Willallison Senior Member

    Very nice indeed!
    And thanks for your thoughts on the interceptors.... it confirms my expectations.
     
  6. HJS
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    Location: 59 45 51 N 019 02 15 E

    HJS Member

    I would prefer a hull that works efficient in both low and high speeds.
    This boat is under construction and we hope to test it soon.
    It will have an interceptor over the whole transom.
    The test showes that it is possible to create a boat that works efficient in both displacement mode and in planing speed with an aft interceptor.
     

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  7. Willallison
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    Willallison Senior Member

    Hmm... looks familiar....;) Is it just the angle of the model, or does your chine angle down towards the bow?
    HJS, it's not so much a question of efficiency - or indeed of improving efficiency - that I was referring to. In fact the boat in question achieves better than 4 nmpg regardless of speed. It's simply a matter of having the ability to trim the vessel - both laterally and longitudinally to suit the prevailing conditions.
    Have you considered the effect of having an interceptor directly in the path of the propwash?
     
  8. rbrooks
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    rbrooks Junior Member

    You are correct. Some of the Carolina builders carry the tumblehome too far forward also with an extreme flair. The combination is fairly unattractive to me. I like tumblehome and flair, in reasonable moderation.
    We have a new project on the drawing board. We are looking for investors to get it off the ground, if anyone is interested.
     
  9. HJS
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    Location: 59 45 51 N 019 02 15 E

    HJS Member

    Willallison:

    Is it just the angle of the model, or does your chine angle down towards the bow?

    The chine is in this case paralell to the waterline

    Have you considered the effect of having an interceptor directly in the path of the propwash?

    It has been done.

    HJS
     

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  10. Willallison
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    Willallison Senior Member

    Interesting looking beast - do you have more pics?
     
  11. HJS
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    HJS Member

    The beast!
     

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  12. yipster
    Joined: Oct 2002
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    Location: netherlands

    yipster designer

    frend of me put self made longer trim tabs on the bennets, easy done and works well
     
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