speed around a course

Discussion in 'Multihulls' started by Bruce Woods, Feb 4, 2008.

  1. kdickson
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    kdickson New Member

    Just to demonstrate how far the monos can be pushed if its taken to the edge - try these two video clips

    http://www.sailingscuttlebutt.com/media/08/0204/

    Hard not to be impressed and noting for all those concerned at the number of crew required to push a mono - there's only one man on this boat. Personally I will stick with the cat secure in the knowledge that 9 times out of 10 a similar length mono won't get a look in and has no accommodation at all by comparison
     
  2. Pericles
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    Pericles Senior Member

  3. charmc
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    charmc Senior Member

    Bill and Kerry,

    Welcome. Thanks for your insights from the perspective of frequent, or at least regular multihull racers.

    Bill, you're correct. Overgeneralization is pointless. There are very fast monohulls; there are cats that are fast in some conditions and slow and awkward in others.

    Kerry, if there is one general statement that might apply, it's yours that, among boats built for speed, a cat will usually yield more speed at a lower cost.
     
  4. charmc
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    charmc Senior Member

    What if North America discovered by Polynesians?

    Funny comments on mono vs multi hulls:

    A clever twist of history is pointed out in "Cruising Multihull Fundamentals" by Rick White. He poses the question:

    "What if America had been discovered by the Polynesians, rather than Scandinavians? Well, we'd all be sailing multihulls. Then Someone would come along and say, "Hey, I have a great idea. I'm going to design a boat with just one hull."

    Everyone would ask how it would keep upright and Mr. monohull would reply, "weights and a deep keel. I'll put a lot of weight down deep in the water."

    Then everyone would ask if that wouldn't make the boat go very slow, and he would enthusiastically reply, "Yes!, Yes!, YES!". You can bet slow and heavy would soon have advocates and a new novelty would be born."
     
  5. brian eiland
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    brian eiland Senior Member

  6. brian eiland
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    brian eiland Senior Member

    Sail Shape factor

    ...on another forum, Roy Mills gave a nice answer to another gentleman's inquiry


    Joe, at low speeds the crucial drag factor is surface friction or wetted surface, not hull shape. Two long thin hulls have a lot more skin area than one short fat one, even if they are not having to hold up quite as much weight. And our superior sails tend to be very flat in light winds and no heel to help them fall into a nice curve by sitting on the lee gunwhale like monos can. Tris are a bit better than cats in both of these regards and that is part of the reason that tris do better in light winds than cats do.

    In a decent breeze, once our boats get up to a speed in knots of around point 8 times the square root of the waterline length in feet, then hull shape starts to overcome wetted surface as the main drag factor, and there is enough breeze to shape the fully battened main sails into a reasonable curve, and we start to leave the monos behind, and the more it blows, within reason, the more we leave them behind.

    Roy Mlls
     
  7. tspeer
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    tspeer Senior Member

    I have both an asymmetrical spinnaker and an Outleader kite for my boat (34' Chris White designed trimaran). Each sail has its advantages.

    The spinnaker is the way to go for light winds. There's a minimum speed required to keep the kite aloft, but the asymmetrical can be used down to zero wind - at which point it just hangs from the mast instead of going into the water.

    However, the spinnaker produces heeling and pitchpoling moments, while the kite does not. So I think the kite makes a better heavy-air spinnaker. We really have no idea what caps the upper wind range of the kite, but it's not capsizing.

    I suspect the cross-over point will be in the 10 - 15 kt range. It will also depend on the point of sail and whether a lot of sail handling is required (around the buoys vs distance race).

    That said, I've very little experience with the kite, yet, and what experience I have had has been under light, marginal conditions. I'm looking forward to getting a crew trained up to where we can fly the kite in high winds and see what it does.
     
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  8. Bruce Woods
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    Bruce Woods Senior Member

    more data

    Race 6 just completed in 8 to 14 knots of wind and calm sea.

    Both Schionning 14+ meters(performance cruisers) flogged by 25 minutes in 132 minute race by adams 13.7, 20 minutes by northshore38 and 18 minutes by 10.3 meter unidentified mono.

    I don't thing joe adams would like his boat being described as anything other than a performance cruiser.

    Food for thought?
     
  9. Pericles
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    Pericles Senior Member

    Bruce,

    Yes, inescapable thought occurs, don't build Schionning for now. :D

    Go for your namesake. http://www.sailingcatamarans.com/
    Go for http://www.john-shuttleworth.com/default.html
    Go for http://www.f-boat.com/pages/faq.html#anchor150609
    Go for http://www.tennantdesign.co.nz/index.php?page=sailing
    Go for http://www.sailinganarchy.com/review/2005/gunboat48.htm
    http://www.cruisingworld.com/boats-...views/gunboat-48-both-guns-blazing-48606.html

    One swallow does not a summer make. The cats could have had inexperienced crews at racing. A whole host of variables. Anyway, who won the first five races? :D

    Enjoy your sailing and the weather.

    Pericles
     
  10. Alan M.
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    Alan M. Senior Member

  11. Meanz Beanz
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    Meanz Beanz Boom Doom Gloom Boom

    See if you can get the crews to swap and then see what happens. That's about the only way you will work out what is what. I am an ex mono sailor now cat sailor and honestly most cat sailors I have met are clueless (they just seem to want easy cruising sailing). I think that the cats are generally so "forgiving" that their sailors don't learn the finner points of getting them to perform. This is especially evident in lighter winds where the multis advantage is limited. I would say the same for any mono sailor that didn't learn in dinghies, it was always pretty evident that the guys who had learned later in life in "heavy" mono's never developed the feel for it that the dinghy sailors gained.

    I also think that a typical mono rig is optimized for windward work in lighter winds where as multi rigs seem to work a heck of a lot better in 15 knots plus. It just seems so much easier to sail a mono to windward it light winds, the feed back is instant and you know the second that you are choking it. I am finding it hard to develop the same level of feel with the cat.

    Anyway I reckon a good % is in the software :D

    My 2c
     
  12. Pericles
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    Pericles Senior Member

    Beanz,

    "See if you can get the crews to swap and then see what happens. That's about the only way you will work out what is what."

    Well said! Moving the crews around from boat type to boat type would reveal, with more accuracy, the sailing abilities of boats and crews. Politically difficult to arrange, as vested interests are almost always reluctant to expose their tackle in the sunlight.l :p

    Regards,

    Pericles
     
  13. Meanz Beanz
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    Meanz Beanz Boom Doom Gloom Boom

    Pericles

    LOL, It would never happen, bar bragging rights have to be protected at all costs :D

    All,

    IMO if you are serious about learning how to sail fast get into "one design". When larger multis get seriously supported strict one design class racing going the knowledge based will grow exponentially.

    If you think you are a good sailor go join a hot Etchell or J24 fleet, it might require an ego adjustment but you learn alot and there are b'all excuse's cause the guy next door has the same hardware.

    I read somewhere that Schionning wants the Radical Bay 8 to be one design, I think you need strict control over the building to achieve that (i.e. one builder) hard to do when you are selling plans. Lets see if he manages to do it, mind you it would be helpful if it where a standard rig. A bunch of hot "bi plane" jockeys might not be so useful in cluing the rest of the cat sailing community up.
     
  14. Meanz Beanz
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    Meanz Beanz Boom Doom Gloom Boom

    Did I read somewhere that the Firefly design is class raced? Is that one design?
     

  15. Guest625101138

    Guest625101138 Previous Member

    Not around a course but the Brisbane to Gladstone race is one ocean race where multihulls and monos "compete" over the same distance. The recent results have line honours dominated by the cats.
    Here are the monos:
    http://www.brisbanetogladstone.com.au/LinkClick.aspx?fileticket=D0CtS0F8D+o=&tabid=62&mid=513

    Here are some multi results:
    http://www.mycq.org.au/big_multi/BM_BrisToGlad/BG_History.htm

    Mono record is 86ft Skandia - 20:24
    Multi record is 56ft Raw Nerve 18:55
    Both set in 2004.

    Rick W.
     
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