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  1. #16
    Join Date
    Apr 2001
    Ontario, Canada
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    Quote Originally Posted by Torben E View Post
    I own a small cat that has a big hop / hump zone and would like to ask if there is somthing
    i can do to reduce that. The hop starts as early as 50 mph and stops around 80...
    Hi Torben - your porpoising experience is pretty common for tunnel boats. Porpoising is more prominent with hull designs that have lower Deadrise (sponsons) OR higher Trim Angles. Often tunnel hulls have BOTH, and so they can often see the onset of porpoising more easily than other hull types. A boat that is susceptible to porpoising will start the process when it's triggered by a change in dynamic balance, such as entering the "Hump Zone". Tunnel hulls also have quite a pronounced Hump Transition, so this can be a significant trigger for the onset of Porpoising.

    There are some things (other than design optimization) that can be done to change the velocities of the Hump Transition and to minimize the drama of porpoising. Some of these have been suggested in your thread above.

    You can also have a look at this Porpoising Article here.

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  3. #17
    Join Date
    Jun 2014
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    Thanks for the answers. They are very appriciated
    There are some things i need to try. And some reading to do.
    This is a great forum for fast boats, im sure the best on the net

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