How to Tame the Porpoise
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How to Tame the Porpoise

  1. #1
    Junior Member
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    May 2012
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    Default How to Tame the Porpoise

    I recently acquired a 2007 24 ft Aftershock party deck boat, tunnel hull, 496HO and 24 pitch four blade prop. Overall we are pleased with the boat with the exception that it porpoises from first planing out up to about 35 mph. After 35 she seems to be manageable with the trim switch, but does porpoise after wakes and chop if the trim is up a bit, and does fine when trim is down. The boat does not have trim tabs or plates and I can only assume (yes assume) that these could help tame the porpoising.

    I called Dana Marine and they recommended that I install their hydraulic trim plates, and they had just installed them on another Aftershock 24 like mine, and solved the problem.

    So, the question is... Do I need adjustable or fixed trim plates, or is there a better bang for the buck besides more bow weight?

    Any ideas?

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  3. #2
    Senior Member
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    May 2011
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    Quote Originally Posted by bronco t View Post
    I recently acquired a 2007 24 ft Aftershock party deck boat, tunnel hull, 496HO and 24 pitch four blade prop. Overall we are pleased with the boat with the exception that it porpoises from first planing out up to about 35 mph. After 35 she seems to be manageable with the trim switch, but does porpoise after wakes and chop if the trim is up a bit, and does fine when trim is down. The boat does not have trim tabs or plates and I can only assume (yes assume) that these could help tame the porpoising.

    I called Dana Marine and they recommended that I install their hydraulic trim plates, and they had just installed them on another Aftershock 24 like mine, and solved the problem.

    So, the question is... Do I need adjustable or fixed trim plates, or is there a better bang for the buck besides more bow weight?

    Any ideas?
    I would talk to a prop guy maybe put some bow lift in to help carry the bow a couple of hundred dollars may solve the problem

  4. #3
    Junior Member
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    May 2012
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    6

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    Never heard of a prop that can slam a bow down... Learn something new every day. That would be sweat if it could be solved with little expense.

    I know a guy who bought the same boat in 2007, but with giant Merc outboard. He blew the motor three times and then switched to an inboard, and his started to porpoise after the motor change. He added manual sponson plates and his problem went away. I can only assume there is too much weight in the stern

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