Aft weight reduction and performance

Discussion in 'Powerboats' started by Art_H, Jan 15, 2008.

  1. Art_H
    Joined: Dec 2005
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    Location: Canada

    Art_H Junior Member

    I'm looking to get a Formula 292 1990-91 Offshore style boat. Dry weight is 7400 lbs. it is a true 29' with a swim platform mounted to the transom also housing the exhaust.

    The twin engines stock are normaly 454, but sometimes 502 Chev.

    I want to remove them and install an LSX style engine for weight reduction and fuel economy. Both from less weight and the EFI.

    By reducing weight in the stern, 600-800 lbs, how will it effect the overall handling/performance fo the hull?


    Thanks

    Art
     
  2. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    I doubt you will see much difference, especially with an IO, you can Trim for conditions. Fast Turns may be a little different for the better.

    Jango
     
  3. tom28571
    Joined: Dec 2001
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    tom28571 Senior Member

    Less weight is almost always a good thing in a planing powerboat. Less weight aft usually means quicker to get on plane but a possible slight drop in top speed because of lower trim angle below optimum. Lower trim angle means more wetted surface drag. That can be corrected by trim tabs or IO trim so the results should be generally positive.
     
  4. Art_H
    Joined: Dec 2005
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    Art_H Junior Member

    Less weight is almost always a good thing in a planing powerboat. Less weight aft usually means quicker to get on plane but a possible slight drop in top speed because of lower trim angle below optimum. Lower trim angle means more wetted surface drag. That can be corrected by trim tabs or IO trim so the results should be generally positive.


    Just what I was thinking. A little trimming up on the drives. Also Maybe some prop changes that are effective with bow lifting?

    Also, on a 24deg offshore speed hull, how much weight should you have for a safe/comfortable ride? Is 400lbs for a 30' hukk too light? What about max speed handling and safety?

    Thanks


    Art
     
  5. tom28571
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    tom28571 Senior Member

    Someone who deals with this should answer but my guess is: If a deep V is unloaded so that it is too light then I think the issue will be stability. Tender at the dock and at low speed plus perhaps chine walking at high speed if the boat lifts too high. You can always add weight if absolutely necessary although I hate adding weight to a boat.
     
  6. Art_H
    Joined: Dec 2005
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    Art_H Junior Member

    Also, on a 24deg offshore speed hull, how much weight should you have for a safe/comfortable ride? Is 400lbs for a 30' hukk too light? What about max speed handling and safety?

    Just had a look at my post, I meant 4000lbs for the 30ft offshore v-hull.

    Thanks

    Art
     

  7. Steve H
    Joined: Aug 2004
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    Steve H Senior Member

    I would be worried about bow steering at high speeds. Lower speeds I think you would be fine though.

    LSX engine? what is that?

    Steve
     
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