A mainsail without boom

Discussion in 'Sailboats' started by Alexander UA, Aug 7, 2013.

  1. Alexander UA
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    Alexander UA Junior Member

    Is there any projects of Bermuda a mainsail used without lashing to any type of boom (even wishbone boom, leg-o-mutton sail )?
    It might be like the luff stretches from top to steps and long mainsheet traveller from side to side used to control mainsail.
     
  2. michael pierzga
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    michael pierzga Senior Member

    It can be done.

    Why ? The deck traveller will be messy and you need plenty of battens . No leech control offwind.

    Nigel Irens uses it on his Roxanne
     

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  3. waikikin
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    waikikin Senior Member

    I went on a charter cat, off the beach from Waikiki that had such a system, a very long curved track, quite some time ago, I think the helm was aft of the track & guests on the wingdeck fwd of the track... no boom to smack them on the head I suppose. Incidentally, these boats are a terrific value, for a few bucks & cool beverages available.... very highly recommended;)
    Jeff.
     
  4. TeddyDiver
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    TeddyDiver Gollywobbler

    Battens are not necessary, depends of the sail cut. Correctly done no need to any and then you can set brails too :)
     
  5. Alexander UA
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    Alexander UA Junior Member

    Grotto in the form of genoa sheet with a high angle.
    Sail Lyungstrem but one.
     
  6. Doug Lord
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    Doug Lord Flight Ready

    Yes on the Weta tri-no boom at all:
     

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  7. sharpii2
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    sharpii2 Senior Member

    Careful sheeting is needed to get the best out of such a sail, which includes moving the point the sail get sheeted to for different points of sail.
     
  8. michael pierzga
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    michael pierzga Senior Member

    The boat pictured..the multihull..is a toy, not as boat.

    Without a boom, How will you develope the correct sheeting angle when you reef the main ?

    Irens uses big beefy battens...a" boom " inside the sail.

    This system will work, but you carry much weight aloft. The sail will be very Noisey in a sloppy sea with light air.

    When loose footed The internal battens will present a maintence, chafe problem
     
  9. pool
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    pool Junior Member

    some larger yachts, like the SMG catamarans, use boomless rigs combined with behind-the-mast vertical mainsail furlers. Sail profile could surely be improved by using vertical sailbattens.
     

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  10. Guillaume C.
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    Guillaume C. Junior Member

    Farrier as designed such mainsail, at least for the F22, maybe some other models too

    [​IMG]
     
  11. Skyak
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    Skyak Senior Member

    Decent examples are listed above. The question becomes 'what is the benefit and what is the cost?' Boomless designs are often small craft that market the safety of not getting hit with a boom. The foot of the main is generally lower. They often have big battens that make a boom redundant. They are often multihulls that don't sail deep apparent wind angles and always carry a spinnaker for downwind performance.

    The 'cost' is the stress added to the boat and particularly, the lower mast. To keep this stress manageable they give up the ability to pull an extra flat main sail in high winds. If the mast is a constant section, it is unlikely there will be any reduction in weight aloft.
     
  12. Petros
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    Petros Senior Member

    A junk rig can be considered boomless, or it has a lot of small booms. Traditioanly it has a small sheet (a "sheetlet") coming from the end of each "boomlet" or batten. They acutlly have lower stress on the rig than a traditional boom since you do not need to pull large loads on the boom to control twist. It allows for control of twist by adjusting each of the sheetlets. It works well and is very efficient for all points of sail except it does not point well without building some camber into the panels between the boomlets. For most cruisers you would not plan long legs pointing high into the wind anyway, and junk rigs are not confined to only small boats, but also on very large schooners as well.
     
  13. Skyak
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    Skyak Senior Member

    I propose the term 'distributed boom' for these sails with numerous full battens and no large boom at the foot, and particularly for the junk rig with sheetlets. Many of the modern implementations of junk rigs don't have the sheetlets, but I think it was the most advanced feature of the rig. Everybody is concerned with planform but without twist control it's a waste. The AC wings have a fantastic twist control mechanism.
     

  14. Erwan
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    Erwan Senior Member

    Hi everybody,

    Regarding boomless main sail, here is my experience.

    My first A-Cat bought in 88 was boomless without circular track for cost reason.
    The main problem was to manage the gusts windward:
    When releasing the mainsheet tension to open the sailplan, basically, the first effect is just like if you release the footsail tension on a boom fitted sail,
    so the sail gets more draft = the sail section gets more camber.

    Today having the boom pushing on the rotative mast when the pulley-block is at the right place on the sail/boom became the standard.

    But in the meantime I observed a simple and quite smart alternative.

    You can have a ultra-light boom, hanging on the sail foot, between the cunningham ring and the ring at the pulley-block point.

    The boom just addresses the footsail tension, it does not even touch the mast. So it is very light and not helmets are necessary to gybe in the breeze.

    Hope it can help .. a little


    Best regards

    EK
     
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