making a High-Thrust outboard

Discussion in 'Outboards' started by luff tension, Apr 21, 2013.

  1. luff tension
    Joined: Aug 2010
    Posts: 65
    Likes: 7, Points: 8, Legacy Rep: 10
    Location: auckland

    luff tension Junior Member

    I have been looking at a high thrust auxiluary outboard for my catamaran (centre-pod mounted) and the classic 4 stroke 9.9 Yamaha High thrust while a great motor is a bit short on horsepower, Yamaha also produce a 4 stroke 25hp high thrust model but these are way expensive and heavy.
    I was wondering if I could get a 20hp 4 stroke and mate it up with the 2.42:1 gearbox from a 9.9, what could be the possible downsides...
    - they are strong but would the extra hp be too much for the gearbox
    - is there enough space for a enough blade area
    what do the experts think of this one...
     
  2. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 110, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Yamaha also produce a 4 stroke 25hp high thrust model but these are way expensive and heavy.

    Find a used version of what you need.
     
  3. Richard Woods
    Joined: Jun 2006
    Posts: 2,208
    Likes: 165, Points: 63, Legacy Rep: 1244
    Location: Back full time in the UK

    Richard Woods Woods Designs

    I agree, the yamaha 25 is a huge engine.

    You may find a kicker style outboard suits, or check out fitting a 4 blade prop instead Honda do that on their smaller outboards to increase thrust. Or do as fast Fred suggests, I recall some high thrust outboards in the 15-25 sizes or maybe an older Yamaha 25? We had a 2003 model on our previous powercat that was much smaller than the newer version

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
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