Powered Trimaran

Discussion in 'Multihulls' started by hwbd, May 3, 2009.

  1. hwbd
    Joined: May 2009
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    hwbd Junior Member

    Hi all I have been considering my boat building options for some time now. The boat I am now thinking of building is a trimaran about 25ft and powered by an inboard diesel engine, possibly a converted car engine.

    At the moment I am strongly cosidering using oldsailor7's bucaneer 24 plans.

    Are there any other reasonably priced plans out there I should consider? or does anyone know of powered 24ft trimaran plans that are available?

  2. marshmat
    Joined: Apr 2005
    Posts: 4,127
    Likes: 149, Points: 63, Legacy Rep: 2043
    Location: Ontario

    marshmat Senior Member

    Hi hwbd,

    There don't seem to be too many power tris in this size. I don't really know why; small trimarans ought to work pretty well on a theoretical basis.

    There was a good discussion on small tris last year.... http://www.boatdesign.net/forums/multihulls/22-24-trimaran-23449.html
    The focus there is of course mainly on sailboats.

    I'm working on an 8.5 metre (28') motorsailing trimaran design right now ( http://www.boatdesign.net/forums/projects-proposals/trailer-cruiser-revisited-trimaran-27032.html ) that is still a long way from viability, and slightly larger than what you're looking at. In my research on this one I have found very little in the way of existing or stock designs for small power tris. Many of the ones that are out there seem to be custom, experimental and/or one-off jobs.

    You may find what you're looking for.... then again, it is equally likely that you may end up taking on the challenge of doing the design yourself.

    Any targets re. use profile, speed, weight, etc.?
  3. hwbd
    Joined: May 2009
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    hwbd Junior Member

    I have read the discussion on 22-24 tris.

    I would be interested in a 28' design possibly, what is the width? Yeah Im thinking of building from the bucaneer 24 plans and modifying the rear and installing an inboard diesel so I suppose that woulb be another one off.

    Speed is not of great importance but I would be looking to use an engine that would at least equal the speed achieved under sail on a 24. So maybe 20knots+.

    Use would be comfortable overnight accomadation for two. I havnt given weight any thought to be honest, but the lighter the better. Saying that I plan on using cheaper materials for the build.
  4. Chris Ostlind

    Chris Ostlind Previous Member

    Hi hwbd,

    I have two power tris in development that you may find interesting. Both of these boats were originally designed for the smallest engine possible with max efficiency while driving the boats at a 12 knot cruising speed.

    They could, of course, go faster, as long as one realizes that they will be sacrificing best economy for the extra speed.

    The smaller of the two, at 24' LOA, is designed to carry two adult passengers on a 10/1 length to beam ratio hull.

    The larger design is 30' LOA and designed for four passengers on a 9/1 hull.

    Both designs are for stitch and glue plywood an have simple plywood and glass box beams for the akas. While both boats can take a modest inboard engine, they are designed for the power to weight ratios of four stroke outboards. Modifications to either boat for inboard power are within the scope of the designs as they were also meant to take electric drive systems.

    Attached Files:

  5. bruceb
    Joined: Nov 2008
    Posts: 1,232
    Likes: 42, Points: 48, Legacy Rep: 214
    Location: atlanta,ga

    bruceb Senior Member

    powered buc 24

    hwbd, I have a Buc 24 and though it looks easy to build and is a good sail boat, I don't see it as a very good power boat. Mine is lighter than some (I don't have a cabin), but any more than 3 normal crew and gear will overload it. It also has too steep of aft hull angle for a good power boat, it would squat with very much power. There are small automotive diesels (Smart cars and others) that could be used in a proper hull design. Bruce
  6. hwbd
    Joined: May 2009
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    hwbd Junior Member

    Hi Chris very interested in your two designs, I wouldnt mind building either size, what kind of width are the two designs? the economy is a very appealing aspect to me. When do you reckon you will have the design completed? and how much are you looking for the design?

    cheers Henry
  7. hwbd
    Joined: May 2009
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    hwbd Junior Member

    Thanks bruce I think Ill rule out the B24 then and look at other designs. good idea with the smart cars the 800cc engine with 40hp would make a great boat engine
  8. jamez
    Joined: Feb 2007
    Posts: 514
    Likes: 32, Points: 28, Legacy Rep: 231
    Location: Auckland, New Zealand

    jamez Senior Member

    How much 4 stroke power would be required for either of your designs to reach a) The designed 12 knot cruise speed and b) a 20 knot cruise speed, at say half to two-thirds throttle?
  9. Chris Ostlind

    Chris Ostlind Previous Member

    The big boat (SurfBus) is going to take 20-25 hp to move along at 12 knots. It will need 50 to do the 20.

    The smaller tri (Javelin) uses 10 hp to do the 12 knot target and 25 to bang out the 20 knots suggested.

    Personally, I like the Yamaha Hi-Thrust models. They're quiet, sip fuel, remarkably dependable and last a long time with normal maintenance.

  10. Chris Ostlind

    Chris Ostlind Previous Member


    I have sent you a PM in response to your questions.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.