Great Loop Multihull Trawler Design

Discussion in 'Boat Design' started by Sundevil, Feb 24, 2012.

  1. mydauphin
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    mydauphin Senior Member

    Are you going to live on this boat for the trip? It gets cold in the winter, hot in the summer and rough in some areas. You need a boat you can go below. Nothing wrong with CATS, but you need a bigger one for better stability and livability.
     
  2. eyschulman
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    eyschulman Senior Member

    The 45 degree angle works fairly well with a good mono that can also do 90 well where the cat may hobby a bit much at 90
     
  3. Richard Woods
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    Richard Woods Woods Designs

    I never heard that one before!! Most people think a catamaran has more room than a monohull, whether power or sail

    So probably just a slip of the "pen"

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  4. Sundevil
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    Sundevil Junior Member

    The whole idea of the Great Loop is to avoid the cold of winter (for the most part), and the extreme heat of summer by migrating North and South. That is one of the main reasons I want to do something like this. :)
     
  5. FAST FRED
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "I guess the next thing I assume is that a multihull boat getting hit from the side with waves/wakes like that won't rock as much."

    It wont CONTINUE to rock, but the initial acceleration of a beam strike may be 3x or 5x as much as a boat that will simply roll.

    Tied to the usual dock along the waterway the rapid up acceleration from passing wakes , will only be part of the fun.

    The thin skin required by lightweight construction will be tested against the dock constantly,24/7

    The "proper" cure a a breast anchor or two to keep the impact loads down is dangerous as too many of today's marine motorists do not know to look for lines off a docked boat.


    "I'm not sure why you say a monohull is more economic than a catamaran. A 36ft power catamaran would only need twin 9.9hp outboards to run at 8 knots, or at 6 knots with one 9.9hp. Which relates to around 10mpg at 6 knots and a minimal initial engine cost, certainly when compared to an inboard engine"

    When slow speeds are considered , a monohull OF THE SAME WEIGHT will have far less wetted surface , and at low speeds thats what you pay to move.

    Most 35 ft (28? LWL ) will easily get 10nm /gal at SL1.1 or so.

    Almost 6K and the huge advantage is an extra 1000lbs of stuff or crew or even 3000lbs will only increase the fuel burn a tiny bit , and not overly burden the vessel.

    If speed is the game multihulls are an answer , but for ditch crawling , there are far too many compromises required.

    Just contemplate the exterior area that is a heat loss for a winter aboard.

    FF
     
  6. sandy daugherty
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    sandy daugherty Senior Member

  7. mydauphin
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    mydauphin Senior Member

    The smaller cats, under 30', have very small hulls that are pretty useless. They basically end up with one big saloon for everything. A 30' monohull has a above and a below which is useful. Same thing for stability, a large cat over 50' is ten times more stable than a small cat.
     
  8. RichardR
    Joined: Oct 2005
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    RichardR Junior Member

    Presto 30 Great Looper

    I am currently developing our Presto 30 as a power sharpie for cruising. 30' loa, 8'6" beam, 13" draft board up-5' 6" centerboard down, 4500 lbs., sleeps 4, 6' 3" headroom, 14 hp Nanni inboard or 9.9 Yamaha high thrust. 1/2 gallon per hour @ 6.5 knots. See Ryderboats.com
     
  9. Richard Woods
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    Richard Woods Woods Designs

    Well I guess I'd better find out the hard way whether you can do the Great Loop in a catamaran....

    Attached is a photo of me going through a lock in a small catamaran.

    I have also been through the Kiel Canal several times in under 30ft catamarans and through the Panama Canal

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     

    Attached Files:

  10. KnottyBuoyz
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    KnottyBuoyz Provocateur & Raconteur

    We've seen all kinds of boats doing the Loop but this would my choice if I could afford one.

    [​IMG]
     
  11. Sundevil
    Joined: Jan 2012
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    Sundevil Junior Member

    What kind of boat is that? The size looks about right, but I would rather have a higher ceiling on the main level than the high second one.

    I have never heard of that Flip research ship. It is a very interesting design. But adding design features to catch currents and roll stopping things that sailboats use when anchored would be nice to have.
     
  12. tom28571
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    tom28571 Senior Member

    One problem with designing a cat is getting adequate bridge deck clearance while keeping the overall height within reasonable limits. Running into even a mild chop can be very disconcerting with waves whumping against the bottom of the bridge deck. Yes, the cat doesn't roll like a trawler or throw as much spray but that noise and vibration can be maddening. That nice looking cat that Rick shows has a questionable amount of clearance. Too many cat designers go for initial impression of space and accommodation and don't pay nearly enough attention to this problem. There is ample opportunity to run into chop on the great loop.

    Cats should have no real problem in locks other than the additional beam taking up more space and dual engines (for those that have them) will make maneuvering easier.

    Richard, what are your thoughts on adequate bridge deck clearance and how big does a cruising cat need to be to get it?
     
  13. KnottyBuoyz
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    KnottyBuoyz Provocateur & Raconteur


  14. mariocroatia
    Joined: Feb 2012
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    Location: dubrovnik croatia

    mariocroatia Junior Member

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