Monohull verses Multihull powersailers / motorsailers

Discussion in 'Motorsailers' started by brian eiland, Aug 8, 2004.

  1. longliner45
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    longliner45 Senior Member

    thankyou gilly ,such a treat for me ,brings back really good memores, those are really good boats!
     
  2. FAST FRED
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    FAST FRED Senior Member

    "CC for coastal cruiser, "

    Can you honestly concieve of the advertising dept of a 50 ft tub alowing a CC rating to be published?

    Most will try for catigory "A" even for a dink.

    FAST FRED
     
  3. Greenseas2
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    Greenseas2 Senior Member

    Multihull sailing efficiency

    I believe that James Wharram has put out some good data on catam,aran sailing efficiency that would be valuable to this forum. The best figures for a cat under sail in the 40 to 65 foot lengths seems to be 3 times the square route of the waterline length in moderate wimds. There have been several claims of 21 knots by cat sailers which is just about right. However, I fully concur that a monohull is best for passagemaking predominently due to it's weight carrying ability. I've motorsailed on long distance passages and find it very comforting to keep the engine running 100% of the time. This precludes the need for a wind charger or generator by simply installing a 100 amp alternator on the engine. The particular engine that I had was a Volvo in the first boat and now have a Yanmar that I find is great at low rpm. I will look up the data on the Saab however. The first long cruise was with a 32 foot schooner (40 LOA). Most of the time the foresail was the only one needed. Chucked the schooner and bought a 30 foot S2 centercockpit that is better, but usually only deploy the genoa. With an 18 gallon diesel tankage, we were able to go from Annapolis, Maryland to south Florida on only 28 gallons of biodiesel at 46 cents a gallon. That's a fuel cost of only $12.88 for the entire trip.
     
  4. globaldude
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    globaldude court jester

    Good news - not !

    Oh dear , my friend has not long purchaced a Wharram cat and wants me to sail with him down the west coast to Wellington from Whangarei !!!.
    I was a bit concerned about it being lashed together as it was, now I'm definately concerned !!.
     
  5. Greenseas2
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    Greenseas2 Senior Member

    Wharram cats

    As with any lashings, they have to be checked and tightened rather frequently. Also, before making any hasty decision about the Wharram catamarans, I would check with James Wharram personally to reasolve any issues with the lashings. If you are uncomfortable with lashings, consult with another well known catamaran designer and modify the vessel to the point where you are comfortable with taking it to sea. The most intelligent factor in safe boating is "common sense".
     
  6. Lyle Creffield
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    Lyle Creffield Junior Member

    Functional economical world motorsailor

    Hi

    You have raised some very good points:

    low RPM diesels make good sense with the cost of increased engine wt
    variable pitch/large diameter prop. -3 blade over 12t disp.(my guestimate)
    one litre per hour is impressive @ 4kns for 14t disp. 11m LWL

    Cats (multis) are cool for protected waters-inside the reef (the great barrier reef) here in eastern Aust. but for me who believes - "boat that sails across ocean bound to roll over sooner or later" adapted from old Confusous tale, it is a mono for my money

    I have not crossed oceans but a 3-1 (sail/motor) cost ratio seems about right i would have thought not many sailors appreciate the fact

    From memory the 10% power loss factor for energy conversion from rotating shaft/flywheel to generator/electric motor, belt drive, hydraulic drive, with shaft var. pitch prop. the most efficient

    tooth belts are better but negates the KISS principle

    Have you considered the diesel outboard from your new project?


    cheers

    lyle
     
  7. FAST FRED
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    FAST FRED Senior Member

    "she had a semi displacment semi planing hull. in 3 to 5 ft seas we could do 20 knots and burn 1.5 gallons per hr .loaded."

    20K on only 1 1/2 Gal per hour is difficult to concieve of.

    20K on 30-35 hp? Would rank her as the most economical boat in the world !!!

    FAST FRED
     
  8. brian eiland
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    brian eiland Senior Member

    Displacement Glider, PowerKeel, etc

    A very interesting new subject thread has recently been posted having to do with a monohull approach to long-range ocean cruising:

    Displacement Glider, PowerKeel, etc

    One aspect of it I find intriging is the idea of a marriage between the PowerKeel hull concept and Paine's Steadysailer design.

    Some of you that have participated in the discussions on this thread might find it rather interesting
     
  9. brian eiland
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    brian eiland Senior Member

    Exciting New Design Motorsailer

    Thought I might revitalize this subject thread so it doesn't die away.

    I am working on a very exciting new catamaran motorsailer design, but I intend to enter it in the Westlawn/Cruising World Design Contest and thus am unable to release any information at this time.

    ....a teaser...It will have a few attributes mention here:
    Offshore Sportfishing Motorsailer, innovations & alternatives
    http://boatdesign.net/forums/showthread.php?t=14900
     
  10. yipster
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    yipster designer

    ...
    so we are not getting a very exiting preview before august eh? :mad:

    when i saw about the contest i was thinking of entering my version of here shown and talked about
    powercatsailer wavepiercer with bipod aft and folding away sail mast on a more of a powerboat style cat

    i asked westlawn if that was within the rules after i allready had shown my sketches and ideas here

    frendly answer was that previews on website or this forum was ok long as it was not build or something along those words

    getting shorter day now, when finishing a decent freeship drawing i like to put it in that design database too
    and hope to be in time with mission statement and asked drawings to content westlawn, wanna enter together? :D

    hope we did not borrow to much from eachother as i can only apriciate your inspiration and expertise on paralel and similar ideas

    anyway, hope we make it in time and see the new concepts perhaps sail someday...
     
  11. FAST FRED
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    One of the most interesting versions of the NJ Sea Skiff was done for Motor Boating in the 60's by Atkins.

    While the boat was not quite as fast as a flat bottomed skiff , it was said to have excellent weight carrying ability , but more importantly could take the ground AT SPEED with no damage.

    The box keel had a simple tunnel aft that kept the prop out of the sand , while sliding over shallow obstructions.

    Any one have a more modern design with this ability?

    Would happily loose a Knot at top speed to have this , cruisers delight!

    FF
     
  12. catmando2
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    catmando2 Malaysia bound....soon


    WIth modern ropes like spectra this is less of an issue

    Dave
     
  13. brian eiland
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    brian eiland Senior Member

    DynaRig (Square rig) MotorSailor, ala Maltese Falcon

    No Ypister, just had to wait till release info was published on my own site per contest rules.(BTW, I don't think our ideas crossed paths per our private discussions)

    So here is a cross-reference to my new design subject thread:
    DynaRig MotorSailer, ala Maltese Falcon
    http://boatdesign.net/forums/showthread.php?t=16276
     
  14. yipster
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    yipster designer

    Brian, good to see you did enter the contest

    think i comply'd with the rules but doubt my half a powercat design has much chance here
    mailed my concept with discussed design brief in time also but feel this design still needs more thinking
    did sections but not fully finished nor did i made tasty renders as my idea is only half finished

    at leisure i'm still checking rig handling on boats like Tiketitan with recessed el or hydro drum winches and get a pic of prices

    i wonder how many and what other designs entered and hope all get some expert response and exposure
     

  15. OldYachtie
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    OldYachtie Junior Member

    Wharrams not lashed with ropes

    Actually, the Wharram cats I have seen weren't lashed with ropes. They had bolts on either side of a connector beam that held down a plate that extended between them, holding down the connector beams. Under the connector beams was a bunch of pads cut from tires, to give the whole assembly some ability to flex. The assembly didn't look very strong to me, considering the job it had to do.

     
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