Armstrong Bracket Hight On 32 Power Catamaran

Discussion in 'Boat Design' started by flboats, Mar 18, 2016.

  1. flboats
    Joined: Mar 2016
    Posts: 13
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    Location: Grant FL

    flboats Junior Member

    I have a Prokat 3200 power catamaran with pair factory Armstrong brackets. The factory setup was for 30" outboard engines, so the bottom of the bracket was about 5" above the keel line. I bought the boat without engines and I had chance to buy 25" 2008 counter rotation Evinrude E-tec outboard motors. The shape of the bracket identical as the hull shape, so I can lower the brackets even with the bottom of the hull, I will have almost 2' setback, because the shape of the bracket from the boat transom going up about 6" I will have no problem to set caviation plate height about 2" above the boat keel. Looks good, I can use my 25" motors, but anyone can tell me advantage vs disadvantage of the installation like this?
    Thank you for the help
    George
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    The only possible advantages from set-back, elevated engines are a little extra speed, and the prospect of more internal room available in the boat. Possible disadvantage is greater propensity to porpoise ( on cats particularly), but in a boat with relatively light engines, shouldn't be too bad. I don't know anything about your hull, but 25" might be cutting it a bit fine for powerhead clearance from the water. Cats can drown motors, perched out there on the extreme corner of the boat, is a place where surging water (at rest) sometimes get uncomfortably close to entering the engine innards. So install them as high as you can without causing ventilation issues.
     
  3. flboats
    Joined: Mar 2016
    Posts: 13
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    Location: Grant FL

    flboats Junior Member

    This is a planning hull, so has relatively wide pontoons, draft only 20", I never drive the boat yet, but there is the video on youtube from the same boat looks ok, the water never get too close to the powerhead and that boat has motors on the transom without bracket. I know the brackets extra weight, but also has extra flotation.I think to lower the brackets even with keel line will be good, what I think just like a car in the wind, if you have everything lined up the wind pass thru on the body smooth, if you have something hanging out or in just creating turbulence, but this is just my idea, this is why I'm here to get answer has more than ideas. I have a other option, I can 5" lower unit extension kit, but I don't like that because there is 5" piece extend the driveshaft, so I'm worry about wobbling.
     
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