Work Catamaran Hull Lines

Discussion in 'Multihulls' started by valter.f, Aug 17, 2014.

  1. valter.f
    Joined: Jun 2013
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    Location: brazil

    valter.f Junior Member

    Hi Efficiency,

    Let's opt for twin diesel engines. Any speed above 20 kts would meet expectations. The weight "load" would be between 5 and 7 ton.

    Thanks,
    Valter.
     
  2. Richard Woods
    Joined: Jun 2006
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    Location: Back full time in the UK

    Richard Woods Woods Designs

    The displacement of my Skoota 36 is 4.8T floating on its marks. I would expect twin 60hp will give you speeds in the low 20's. I have done a 5T sailing 35ft catamaran that did 22 knots towing a waterskier with twin 90hp. Obviously that had a sailboat hull and a high windage mast and rig, so a powercat would be more efficient, thus faster

    Richard Woods
     
  3. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Load as in additional to unladen weight ? That is going to be a very heavy boat for a 30 foot catamaran , and 20+ knots cruise specification. BW seacat specifications should tell you how realistic this is.
     
  4. valter.f
    Joined: Jun 2013
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    Location: brazil

    valter.f Junior Member

    The molded catamaran above 50 ft, twin engine 600 hp and carries 25 ton plus weight of boat, cruising speed 20 kts. Our might even be a little larger, 35 ft, twin engines 350 hp. Will depend on the volume of hulls (m³).
    Will also have positive fluctuation. Maybe we'll need 4,000 rpm loaded, but I think we got 20 kts with 5/7 ton or 15 kts cruising speed at 2.500 rpm. Would still be within expectations.

    Beautiful cabin: [​IMG]
     
  5. TANSL
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    TANSL Senior Member

  6. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    I apologise, I think I misunderstood your requirements

    From the later posts it now appears that you want a 30ft powercat that can carry 7T payload and will motor economically at 20 knots. Sorry, that's like putting 7T in a pickup truck and expecting it to do 70mph at 40mpg

    or maybe I misunderstood again
    Richard Woods
     
  7. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Richard

    I don't think he knows what he wants. He has models, but doesn't have lines. He wants chines, but doesn't realise those models have chines, he has lines, but doesn't have the ones he wants.

    "..Lets op for twin engines....may be 4000 rpm loaded...i think we get 20 knots..." etc. ..it is an endless circle.

    He has no SOR and it is loud and clear he doesn't. He's just fishing for "something" for free by the looks of it to me. As also noted here:
    http://www.boatdesign.net/forums/multihulls/catamaran-hull-lines-48478.html
     
  8. valter.f
    Joined: Jun 2013
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    Location: brazil

    valter.f Junior Member


    Mr. Ad

    I must say that you were very unhappy in their placements. I make it clear at the beginning of my post the following words: "I have several plans not used for exchange or we can negotiate a sale price"...
    I do not have the bad habit of asking anything free to anyone, so little of be rude to with someone that I am unable to help.

    I think you should improve your reading. Note that in that same post, I inform that already "bought" the plans of Mr. Richard and believe me, I paid for them... In fact, I have over 40 plans that I "bought" of many
    other designers Americans, British and Canadians, all talented and very more educated than he and his Bootlickers. SO:

    Mr. Ad,
    Please, in future not make immature comments on my posts.

    Richard,
    I do not want to buy your plans! Please, stop insisting!

    Thanks,
    Valter.
     
  9. FMS
    Joined: Jul 2011
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    Location: united states

    FMS Senior Member

    What do you call this on your model?
     

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  10. FMS
    Joined: Jul 2011
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    Location: united states

    FMS Senior Member

    What is "positive fluctuation"?

    And how is "our" 35 ft 5/7 ton "a little larger" than the 50 ft 25+ ton (?) boat referenced?
     
  11. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    I am sorry, I didn't mean to offend you. Not sure where I did. Maybe it is a language problem.

    I offered to sell you Skoota 36 hull plans and you replied, paraphrasing, "Sorry my friend you are right, I will contact you through the site". I didn't mention selling plans to you again

    Then from later posts I realised you didn't want the Skoota anyway. I merely pointed out that you are probably asking for the impossible. Or rather, if you can achieve a 30ft catamaran with 7T load carrying, and do over 20 knots economically, then you will have a breakthrough design. Beyond my capabilities I'm afraid.

    Richard Woods
     
  12. valter.f
    Joined: Jun 2013
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    Location: brazil

    valter.f Junior Member

    Hi FMS,

    As you can see above, this post should be terminated. I've also got a friend working on the boat project and I will buy the plans with him. Depending on the outcome, I can point it out in the future.

    In relation to your question about "positive fluctuation" I expressed myself badly. My English is very bad, sorry. Search on "positive floatation boat" and you find answers to all questions on this subject.

    Thanks,
    Valter.
     
  13. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Since he has this model (but even that is not 100% clear)..he must also have the Lines to make the model ...so why is he asking for Lines?
     
  14. FMS
    Joined: Jul 2011
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    Location: united states

    FMS Senior Member

    Unclear. Either he doesn't have those lines or he wants something that meets some different needs. The term chine may be being used incorrectly too.

    I don't know the economics of building or operating a commercial / "workboat" in Brazil. Possibly these are very different from what I know.

    I don't think you will find stock plans for exactly what you want.

    In the United States where I know the economics, twin diesel engines and the cost of materials and labor to build a 30' boat are both substantial.

    I would start with the budget for the whole boat and the specific requirements it has to fulfill.

    Make sure there are no used boats that will meet your needs far less expensively.

    Then hire a designer for either consultation or design work that has done similar work. Even if there are stock plans, I would consult a designer. Determine if that best fits your needs before starting an expensive boat. For a commercial operation there is usually much more cost of use (fuel, crew, etc) than for a small recreational boat. Saving fuel every mile or better serving your jobs can be more "affordable" after a few years.
     

  15. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    Valter, no need to apologise for your English, im always impressed when people do so well with a second language.

    Steve.
     
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