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Thread: 8m Engine Upgrade

  1. #1
    Join Date
    Dec 2017
    Location
    Cornwall
    Posts
    8

    Default 8m Engine Upgrade

    Hi,

    I've now got a Catalac 8m with twin 10hp Yanmar (shafts). I've found in some conditions I struggle to manage more than about 2 knots (on engine alone). If I wished to upgrade the engines to a 20hp pair, is there a suitable engine that others have chosen before?

    Linus

  2. #2
    Join Date
    Oct 2008
    Location
    Worcester, U.K., Moraira, Spain
    Posts
    559

    Default Re: 8m Engine Upgrade

    Not specifically Catalac related but I know a couple of people who've replaced Yanmars and Volvos with Beta Marine. They do a 20hp but as it's 3 cylinder it might be physically a bit big. They have a 16hp that is 2 cylinder so might be a better bet. http://betamarine.co.uk/portfolio-item/beta-16/

  3. #3
    Join Date
    Dec 2017
    Location
    Cornwall
    Posts
    8

    Default Re: 8m Engine Upgrade

    How concerned should I be about extra weight?

  4. #4

    Default Re: 8m Engine Upgrade

    Quote Originally Posted by uklinus View Post
    Hi,

    I've now got a Catalac 8m with twin 10hp Yanmar (shafts). I've found in some conditions I struggle to manage more than about 2 knots (on engine alone). If I wished to upgrade the engines to a 20hp pair, is there a suitable engine that others have chosen before?

    Linus
    Are you happy with the propellers? I'd check on sizing and pitch of those first, a lot cheaper than an engine change(s). Chances are if you change the engines you will also need to change the props.

  5. #5
    Join Date
    Feb 2009
    Location
    Belgium
    Posts
    371

    Default Re: 8m Engine Upgrade

    Quote Originally Posted by uklinus View Post
    I've now got a Catalac 8m with twin 10hp Yanmar (shafts). I've found in some conditions I struggle to manage more than about 2 knots (on engine alone).
    Linus
    Hi Linus, I suppose that is 2 knots SOG, what currents/headwind are you fighting against?

    Quote Originally Posted by Peter View Post
    Are you happy with the propellers? I'd check on sizing and pitch of those first, a lot cheaper than an engine change(s). Chances are if you change the engines you will also need to change the props.
    I second that, 2 twin Yanmar (in good condition) should be sufficient for the 8M. Props are very, very important so indeed you will need to check if they are the right size/pitch for the 8M (can't help, have an outboard, installed new by the previous owner, also in need of a better prop but this is common on outboards if they are not 'high thrust' versions)...

    I suppose you have a clean hull (not fouled heavily I mean)...
    Any idea how heavy you are loaded now? Full cruising gear? As yes, weight impacts performance, especially aft...
    1979 Catalac 8M - 8-84 - Galu'Lati Go

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