New A Class Catamaran Rig: Square Top Jib

Discussion in 'Multihulls' started by Doug Lord, Jan 17, 2011.

  1. Doug Lord
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    Doug Lord Flight Ready

    From Multihulls on SA(Bob Hodges):

    Finally, Randy Smyth tried a new A-Class rig today that consisted of a smaller (110 ft2) high aspect mainsail coupled with a high aspect 40 ft2 square top jib. He shortened his mast 12" and had to add some lightweight rigging innovation to accomodate the jib including a clever self-tacking jib track that was secured to the front beam with Dyneema line and a central bolted connection. It's a really cool looking rig but unfortunately it only had a short test today. The center portion of the jib track was not secured and it bent during a tack on the first beat of race 1 forcing Randy to retire for the day. He had it repaired this evening and will be back on the water tomorrow. What a game changer this could be if this rig works!

    Coconut Grove Invitational http://forums.sailinganarchy.com/index.php?showtopic=117565&st=0


    click on image and then again on resulting image
     

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  2. Eralnd44
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    Eralnd44 Wanderer

    game changer or maybe another game. this make a design that is looking far to changing game and only small difference to the boat. why you make big talk on the small thing.
     
  3. Gary Baigent
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    Gary Baigent Senior Member

    Headsails on fast cats ... forget it.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    How about headsails on fast tris:
    --Smyth finished mid fleet-not too shabby first time out
    --How about Tornados, USA 17, Extreme 40 catamarans


    Pix: hydroptere, BMW/USA 17, Extreme 40 cats with, yes, headsails:
     

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  5. Gary Baigent
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    Gary Baigent Senior Member

    Doug, I mean headsails used to windward - didn't say they were bad for reaching - but then a reaching headsail is not cut the same as a windward headsail. Hydroptere's is used for reaching. I love the Rodney March boat ... but it did appear 40 years ago. And remembering BMWO; when they pulled the headsail down the tri really started to smoke high to windward over the top of A5. I mean all the C's carry headsails. Catch up, mon ami.
     
  6. Doug Lord
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    Doug Lord Flight Ready

    =================
    Gary, I can't find the quote quickly so I'll paraphrase what Tom Speer said about USA 17: It's a sloop(even without the headsail up)
     
  7. Gary Baigent
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    Gary Baigent Senior Member

    I mean, all the C's carry headsails??
     
  8. Gary Baigent
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    Gary Baigent Senior Member

    I guess any forestay, whether it has a headsail or NOT ... can still be called a sloop rig just because it is capable of carrying one forward. By those terms, then, the only true una rig would be an unstayed rigged version. We're definitely heading into pedantic territory here.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    ========
    You said fast cats don't carry headsails..........?
     

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  10. Doug Lord
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    Doug Lord Flight Ready

    ==================
    Nah--the fact is headsails work well on many fast cats,tris and foilers and square top jibs(though NOT like Smyth's) offer quite a bit of potential).

    click on image:
     

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  11. waynemarlow
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    waynemarlow Senior Member

    I guess what everyone is trying to say is the Uni rig has greater theretical efficiency, what everyone forgets is that 75% of recreational sailors cannot set a Uni mainsail correctly and find it difficult to get optimum settings.

    The front jib creates a much smoother effect over the main and helps the average Joe Bloggs like me to set the main getting a total efficency better than the Uni on its own. In racing terms, its a dud, in Joe Bloggs terms its a very good aid.
     
  12. Doug Lord
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    Doug Lord Flight Ready

    A Class Cat Square Top Jib

    More pictures of Randy Smyths innovative A Class Cat:

    click on image:
     

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  13. Gary Baigent
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    Gary Baigent Senior Member

    Historically the fastest, most efficient to windward (also reaching in those times) boats did not carry headsails: the C Class cats dating way back to Lady Helmsman and Thunder days; the A Class of course and also the Beowulf D Class designs of Dashew (V and VI were years, decades, ahead of their times, una rigs to windward plus quite small reaching headsails downwind). I remember reading of a race off between Sydney Harbour 18's and one of the Cunningham's C's, Victoria, I think; not only did the C stomp the 18's to windward, it also put time on them downwind too; that is a 3 element una rig against the highly touted two sail 18 plus large downwind reacher. More recently the Ketterman foilers like record setting Longshot, had/have two una rigs and they're not bad at reaching too, and yet more recently, the very high performing Marstrom 20 catamaran.
    Mirabaud has a problem; their two foil plus rack design lacks power with the narrow platform so they have to keep the rig low because their righting moment could not handle a taller una rig. The two Hydroptere designs would benefit from una hard rigs, or if not completely hard, larger chord wing masts with una setup. Just IMO of course.
    And when four element, refined, slotted, hard rigs appear in the AC designs, that will be the end of even reaching headsails ... interesting times coming.
     
  14. Doug Lord
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    Doug Lord Flight Ready

    ------
    You can say that again!
     

  15. petereng
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    petereng Senior Member

    Jib on A=Class
    Anyone who does the research and the maths without two much digging will find that the jib is not the way to go. Even from a trimming point of view he'll be flat out trimming main and jib losing time for tactics and getting his head out of the boat. But he may have a balance problem and since he can't move the mast fwd this is a solution. Not the ideal but a solution. Don't be too critical of these things they will easily work/notwork on the racetrack. Cheers Peter S
     
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