Using Volvo Penta Interceptors on a 29 ft Blackfin SF

Discussion in 'Hydrodynamics and Aerodynamics' started by rverone, Jan 13, 2015.

  1. rverone
    Joined: Jan 2015
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    Location: NEW YORK

    rverone New Member

    Interested in purchasing 2 or 4 Volvo Penta 450 interceptors. Due to the hull design of the 1989 29 ft Blackfin SF hul, uI'm interested to find out if anyone has used them. We currently have trim tabs that are working well. But we would like to conserve more on fuel.
  2. keysdisease
    Joined: Mar 2006
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    Location: South Florida USA

    keysdisease Senior Member

    What makes you think interceptors will help you conserve more fuel than trim tabs?
    Typically the thinking with trim tabs is that they allow you to run with optimal hull trim and at lower planning speeds therefore improving fuel economy.
    The performance curves of trim tabs vs interceptors indicate that tabs work better at slower speeds than interceptors so what you seem to be wanting to achieve might not work better with interceptors.
    You may improve trim performance by going to bigger tabs that will trim the hull with less deflection. Your tabs should go from the chine flat inboard 30" to 36" with a 12" chord tab for a boat like that.
    Does that Blackfin have the transom mounted rudders? If so a second set of tabs inboard of the rudders plumbed into your existing system would help.
    If you have Bennett you can probably just switch out the tabs only for a larger size, or a second set with rams to mount inboard, the rest of the system will handle larger tabs or 4 total tabs no problem.
    You will have less drag and better performance from a larger tab deflected a little to get the desired effect than a smaller tab deflected a lot.

    BMcF likes this.
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