Aftmast rigs???

Discussion in 'Sailboats' started by jdardozzi, May 28, 2002.

  1. markstrimaran
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    markstrimaran Senior Member

    Lake trials

    Well went out for the first time in 20 mph winds that gusted to over 30. The rig held at least. Way too rouph for any good data. Still need to work on sail rigging layout. Lee helm is an issue. As is the need to be reefable. It is easy enough too switch sails in windy conditions at least. The pummeling was was taken well. As the out rigger mounts are stought and the boat is rigid. None of the twisting flex that I had last season.
     

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  2. brian eiland
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    brian eiland Senior Member

    Headsails to the masthead, and Big overlaps ?

    Cruising around the internet today, and ran across this.
    http://www.sail-world.com/Play_of_the_Day_-_PUMA_crack_the_Code/49460
    Headsail Size, Std kit and Code Zero.jpg


    Now I wonder why these guys would be using masthead headsails,.....and with such big overlaps.....WOW :rolleyes:
     
  3. brian eiland
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    brian eiland Senior Member

  4. brian eiland
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    brian eiland Senior Member

    Masthead vs Fractional Rig

    interesting discussion on the subject over on WoodenBoat forum
    http://forum.woodenboat.com/showthread.php?146444-Mast-head-vs-fractional-rig

    ...one particular posting I just read...
     
  5. brian eiland
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    brian eiland Senior Member

    Hey Mark,
    I think you could clearly use some better sails. :)

    Why don't you see if you can rotate those images around so they are straight up,...:D
     
  6. markstrimaran
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    markstrimaran Senior Member

    sails

    Ya I sure do. Sailing upwind on a 45.00 ebay sail. Modified on a 1973 Sears sewing machine. The knowledge learned is priceless. As long as the Johnson starts on the second pull.
     
  7. brian eiland
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    brian eiland Senior Member

    2 Reefed Sail Deployments

    Had a recent private inquiry that was asking about 'reefing' of my rig design. I went back thru this subject thread to posting #422 to find these illustrations that I was sure I had posted at one time.
    Reefed Deployment Illustrations
     
  8. brian eiland
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    brian eiland Senior Member

    Big Genoas (or genoa types?)

    I had to go all the way back to a posting I made in 2004 to find this quote of mine....small excerpt...
     
  9. sharpii2
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    sharpii2 Senior Member

    Looked at the rig in question. It looks a lot like a mast aft I.O.R rig, except it has a square top main. Having such, It now needs running back stays, which must be set up with every tack.

    Does not look that convenient or even all that safe.

    Probably better to have a gaff on top of the main, which can be peak dropped for every tack. Seems like it would be a whole lot easier than dealing with running back stays.

    I'd make the mast round in section and have a jack line running up the aft side of the mast, which the top part of the main would hank to. The bottom part, up to the spreaders, would have hoops or lacing. I'd do this so the main would set better on a reach.

    But still I'd expect the fractional rigs to rule.

    It's simply easier, cheaper, and more reliable to put most of the sail area behind the mast, if maximizing sail area is the goal.

    Mast aft boats, IMHO, are for cruising, because they have better anchoring and heaving to aerodynamics and, arguably, more drive per sail area.
     
  10. Kojii
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    Kojii All is remodelling

    Oh, and no ship that's not crewed by the damned and captained by a man so evil that Hell itself spat him back out could possibly have Code zeros, therefore couldn't possibly be any other ship than the (insert race boat name here). Is that what you're telling me?
     
  11. brian eiland
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    brian eiland Senior Member

    Sorry Sharpi, I'm not sure which rig are referring to? ....there are lots of rigs discussed in this forum.
     
  12. sharpii2
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    sharpii2 Senior Member

    I'm discussing the latest one mentioned, of course.

    The one you just mentioned, with the big "code zero" and the running back stays.

    I was only commenting on the need to have to set them up, with each tack.

    I suggested a solution that would allow fixed back stays.

    The boat in question is shown on attachment 100293.

    Now that I'm here, I'll add that, IMHO, big jibs need big crews to get the best out of them.

    This is far more important with a racing boat than with a cruising. With a cruising boat, adequate performance might do, if the rig choice it entails comes with other virtues.

    Such may well be the case with a mast aft rig with a big jib.
     
  13. brian eiland
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    brian eiland Senior Member

  14. Guillermo
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    Guillermo Ingeniero Naval


  15. pogo
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    pogo ingenious dilletante

    Sponberg writes:

    "Another unique feature of Wobegone Daze’s rig is the combination of conventional booms situated below the foot of the sails, and wishbone booms that connect to the ends of the lower booms and to upper goosenecks on the wingmasts. *Inside the lower booms we have Hall Quik Vangs that allow us to control leach tension.* Each Quik Vang is attached to a sliding shaft that comes out the boom’s front end and is goosenecked onto the wingmast.* As you pull or release the Quik Vang line, the boom slides forward and aft about 6” on the shaft, and this causes the aft end of the boom to rise or fall nearly three times that amount, about 18”.* This magnified vertical movement at the end of the boom is what controls the twist of the sail.* Finally, lazyjack lines rigged between the wishbones and lower booms form very nice cradles to catch and stow the sail."
    Source: http://www.sponbergyachtdesign.com/Wobegon.htm


    I' sure you know that booms for selftacking jibs on european box-rulers are set back --the pivoting point ist at about 10 % of J. These booms have a track for foot-leech tension at their end . ( also the boom makes single line slab-reefing possible )Together with sheet tension and a radius traveller with max. beam , one is able to controll twist of the triangular foresail with high aspect ratio / short J ).
    Boom only:
    The farther the pivoting point is back, the more diagonal is the boom. Tensioning the sheet now , means giving less twist AND a flatter sail. In fact, first Generation of Baumfocks ( self-tacking boomjibs ) were designed this way.
    Without a boom one would have no control over sail's belly , only over it's twist ( similar a mainsail without boom)

    Having an additional track on boom' s end ( second generation) , means one can give less twist AND a fuller sail - or vice versa. You have everything -- total control. But , only w. double radiused traveler ( ends up)! Check it out please.


    A foresail with a rounded aftleech and/or longer J , or a square top main behind a rotating mast ( see above ; Sponberg) ,needs for total control an additional diagonal boom coming from above --the wishbone . It' s all about geometrie , vectors ...

    Wylicats have undergone this necessity with a flexible mast--twistcontrol by bending the mast in longutudal direction thru wishbone compression . Furthermore their unstayed masts --the masttops-- the sails-- spill the wind by feathering leewards in gusts.

    There are many ways.
    One is the balanced jib -boom by Hoyt:
    http://www.garryhoyt.com/id38.html
    Segelwerkstatt Stade has an improved very successful version , named " Trecker System":
    http://www.segelwerkstatt-stade.de/cms/index.php/forschung/trecker-system


    By the way , have a look at at the booms for triangular headsails on Chris White's " Junkers Doppelflügel Rigg" .






    pogo
     
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