Cat Estimated speed w/200 hp out board(s)

Discussion in 'Outboards' started by mike w. schultz, Dec 26, 2018.

  1. mike w. schultz
    Joined: Dec 2018
    Posts: 24
    Likes: 3, Points: 3
    Location: South Mississippi

    mike w. schultz Junior Member

    Thanks in advance, I just started laying up a hull for a power cat 48', (Jon Coats Design),
    For many reasons, primarily cost & weight I have elected to propel her with twin 4 stroke out boards. The goal is to get a 12-14 knot cruise at 75% throttle or less, boat weight is estimated to be 18,000#
    Question is what H.P.? does anyone know a manufacture that produces a high thrust outboard in this HP range? Your thoughts and input are appreciated. Thanks Mike S.
     
  2. Mr Efficiency
    Joined: Oct 2010
    Posts: 10,401
    Likes: 1,026, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Mercury has the "command thrust" gearbox option, which spins a bigger prop with more reduction, probably aimed at pontoon boats, but maybe 115 hp is the upper limit. 18,000 lbs is not a lot for a 48 foot boat though, and your cruise speed ambitions are modest. Suzuki has a two stage gear reduction, and I notice a 2.5:1 ratio, on 150 hp. That sounds like a possibility. I'd be going for 30" shaft length, for greater insurance against powerhead "drowning".
     
    fallguy likes this.
  3. mike w. schultz
    Joined: Dec 2018
    Posts: 24
    Likes: 3, Points: 3
    Location: South Mississippi

    mike w. schultz Junior Member

    Thanks for the feed back, not a huge fan of Mercury, my Aussie friend called them "Black Anchors" Great experience with Yam & Suz. Will be mounting engines 6ft. forward of the aft part of the boat hoping to avoid some pitfalls mentioned in other posts. Cost of diesels and related items are getting HIGH!!!! Thanks again. Mike S
     

  4. Mr Efficiency
    Joined: Oct 2010
    Posts: 10,401
    Likes: 1,026, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Black anchor BS is well out of date. Mercury changed the alloy that led to corrosion problems decades ago, and their 4 strokes are cheaper to service, as I understand it. But with a cruise speed in the mid-teens, you are definitely wanting a good gear reduction, with a bigger diameter propeller.
     
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