OB trimaran sportfish designs?

Discussion in 'Boat Design' started by Krauthammer, Nov 10, 2011.

  1. Krauthammer
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    Krauthammer Junior Member

    There are many small to medium size OB powered catamarans but not a single tri, at least not in the US.

    The cats have advantages over monos but they require twin engines rigged behind the sponsons to avoid drag and to give the props a solid bite in displaced water. In 16'-20' sizes they are rigged with singles and the results are less than stellar. Above that size the manufacturers are quick to state that their boats will not run with a single and warn of excessive cavitation etc.

    A 20'-25' center console being the size that is of interest to those who wish to venture in open waters, is burdened with the cost, weight and fuel consumption of the twin engines.

    Why don't we see a manufacturer offer a tri where a single would run behind the center hull while the lift would be provided by the twin tunnels and the shape of the sponsons? In my mind this type of boat would have a softer ride than a cat and better sea keeping abilities in rough conditions. The savings in rigging a single OB and the fuel economy should make it very attractive in a marketplace full of gas guzzling twins.

    As far as deck space is concerned I think that a clever design would provide space at least equal to the cats while the center hull would add a very large additional volume in the place where cats have the flat roof of the tunnel. Taking the beam 12"-18" above the current 8' that most cats in the size range have, would provide additional benefits and trailering permits are easy to obtain.

    Opinions? Any designers willing to design a one-off?
     
  2. river runner
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    river runner baker

    I sent that idea to a famous multi-hull designer, an number of years ago. He sent back some sketches and started talking about a deposit, etc. When I told him to put on the brakes, I was just suggesting an idea, he got all PO'd and told me I was waisting his valuable time. I,for one, think there would be a market for an outboard powered trimaran.
     
  3. Krauthammer
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    Krauthammer Junior Member

    That makes two of us. Who was the designer?
     
  4. river runner
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    river runner baker

    The only name I can think of from that period is Jim Brown, but I don't think it was him. There was another guy that was doing the same sort of things, they may have even worked together, and I think it was this other guy.
    What he told me was that boat designers don't work that way. They don't go to people with ideas, they wait for peope to come to them with ideas for a boat they want built. Seems to me they could be a little more proactive.
     
  5. jmo
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    jmo New Member

    tri's

    Dear Sir

    Our office has been working on this very concept for a while and are just doing the final computer testing of the configuration before the first hull, to be built in aluminium, is started in a few weeks.

    The boat comes as a cnc cut kitset and has been designed with various building materials in mind.

    The response to this design after just one article in a local boating magazine has been way beyond what we expected with most wanting smaller versions of the concept.

    Presently we have a 4.5m, a 5.75m, a 6.1m, a 7.5m plus the original 9.5m commercial fishing boat and the 11m hardtop, all looking to get out to the big fish.

    We are presently negotiating with a Canadian company to start producing these and other designs for North America.

    for further info contact our office via our website

    www.morganyachtdesign.com

    or jm@morganyachtdesign.com

    64 9 4254427


    John Morgan
     

    Attached Files:

  6. Squidly-Diddly
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    Squidly-Diddly Senior Member

    some poster built a med power tri, not sure if it was outboard.

    kinda futuristic curvy looking.

    I think he is Australian.

    Someone should remember.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    http://hydrofieldtrihulls.com/story.php

    These boats have stood the test of time, having been round for decades. A niche market boat, but a nice fishing boat that won't hand out a flogging in rough water, or deep-vee flopping when you pull up to fish. If there is a downside, it is that that adding extra power doesn't really translate into a lot of extra speed, but at the type of speeds it is practicable to cruise offshore, it isn't a worry.
     
  8. eyschulman
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    eyschulman Senior Member

    If I recall right Yanmar did a power tri with there deisel OB motors and as an add stunt like went around the world with it. Not sure might have been a 30 or 40 footer.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    They can be quite efficient at lower speeds, but are not for boy racers, there is a fair bit of wetted area in play.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    Not the Stolkraft ?
     
  11. river runner
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    river runner baker

    The images posted by John Moran aren't really what I had in mind and I don't think it is what Krauthammer had in mind. I was thinking more of a trimaran like you see on sailboats. A larger, but slender, center hull with outriggers. Easily driven so it would be pretty fast with a 25 hp outboard. Something like a square stern canoe with outriggers. Maybe a total width of eight feet for trailerability, or removeable outriggers.
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    Sounds like a nightmare for snagging fishing lines.
     
  13. river runner
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    river runner baker

    Here in the Rockies, catarafts (inflatable pontoon boats) from tiny one person to big three person, are extremely popular for fly fishing (dry flies, of course). Snagging lines must not be much of an issue or they wouldn't be so popular.
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    A big fish can easily take the line round obstructions and be lost. Standing on an outrigger to gaff a trophy fish in a heaving sea is not my idea of putting the odds in your favour.
     

  15. Krauthammer
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    Krauthammer Junior Member

    Perfect and thank you for the response.

    A 6.1m / 24ft in the center console configuration shown on your rendering 450 CC is exactly what I had in mind.

    Far more utilisable space than a cat, seaworthiness, no tunnel slamming, cost and fuel efficient thanks to a single OB. Cost of ownership and operation over a ten year period with an average 250 hrs p.a. will likely be half the cost of a twin engine cat. Anything over 250 hrs should tilt it far more dramatically in favor of the tri.

    I will be in touch.
     
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