why no big cat rigged boats

Discussion in 'Boat Design' started by dionysis, Jan 4, 2004.

  1. dionysis
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    dionysis Senior Member

    I like the idea of just having one sail on a boat, but you do not see many of them on large boats. They have to be simpler and from what I understand - more efficient on the wind.

    Many small boats are cat rigged, and are fast, well balanced and manouverable.

    What is the problem with them on large boats? Any thoughts?

    Cheers, and happy new year.
     
  2. gonzo
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    gonzo Senior Member

    What do you call large?
     
  3. dionysis
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    dionysis Senior Member

    sorry gonzo, - say about 60 ft
     
  4. tspeer
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    tspeer Senior Member

  5. tspeer
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    tspeer Senior Member

  6. dionysis
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    dionysis Senior Member

    Thanks Tom - that's a large sail on that 48 ft one - yep! that is the idea. Gee, that bow section whould need to be engineered well!

    Now, what are it's pros and cons?
     
  7. dionysis
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    dionysis Senior Member

    Excuse me, I should give my opinion first.

    With the tack lower, clew higher and a little less roach on the top third of the sail - like a sailboard sail;

    Pros: clean air, low parasitic and induced drag, cheaper, simpler to rig and maintain - hell! such a rig seems unbeatable for cruising.

    Cons: ?
     
  8. ErikG
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    ErikG Senior Member

    Cat rigs...

    How do you reef the Wylie cat? Looks hard to do with that boom?

    Cons: ugly on yachts, looks perfectly ok on dinghies though, don't know why... :D :rolleyes: It's proobably just in mi hed...

    Since the pic below lokks more than ok, doesn't it?
    [ Int Moth - Rohan Veal (AUS) on foils ]

    Erik
     

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  9. dougfrolich
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    dougfrolich Senior Member

    Tom Wylie has been making 60+ cat rigged boats for awhile.
    This one is a cat-ketch.

    Another of his will be racing in the Vendee race around the world
    check out oceanplanet.org
     

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  10. dougfrolich
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    dougfrolich Senior Member

    here is oceanplanet
     

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  11. dionysis
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    dionysis Senior Member

    Erik, I reckon it's because the dinghies have higher aspect sails, together with loverly sail design - but it's probably just in mi hed too.

    Yes Ocean Planet is a nice looking boat doug. Balancing a boat with a single sail would call for some nice design skills though.

    If I were to choose out of two masted configurations, my preference is for a cat yawl: I like the idea of self-steering using sails only, and the aft sail avoids most of the dirty air from the main.
     
  12. tspeer
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    tspeer Senior Member

    From what I understand, reefing is actually quite nice. It's just regular slab reefing. The sail gathers naturally in lazy jacks that go from one limb of the boom, under the foot, and back to the other limb. The sheet can also be let out to allow the sail to luff regardless of the point of sail.

    Being able to let the boom forward also makes jibing easier in heavy air. The boom is eased as the boat is brought through the wind and sailed comparatively high so the sail is flying by the lee but well forward. Then the sheet is pulled in enough to jibe the sail at a time of the helm's choosing. Although the sail swings across rapidly, there's no crash to the jibe because the sail is allowed to swing foward where the it is arrested gently by aerodynamics as it feathers into the wind. There's also no tendency to round up because there's no load on the sheet. Finally, the sheet is brought in to trim the sail.
     
  13. BrettM
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    BrettM Senior Member

    Sailing by the lee in heavy air easy? Ask any laser sailor and they will tell you that it is definitely a learned art filled with many swims...
     

  14. dionysis
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    dionysis Senior Member

    I wonder wheather that applies to boats without live ballast?
     
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