Ljungström Sail

Discussion in 'Multihulls' started by Newickspark, Jun 16, 2019.

  1. Newickspark
    Joined: Jun 2019
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    Newickspark Junior Member

    Not sure if carbon hoops would stretch to much.

    It’s a combination of newick and Wharram, with a modern square top shape

    Here is what I have, let’s dissect it!

    Newick mast, rotating with an egg shape
    Wharram soft wing sail
    Use carbon rings
    The sail wraps around the mast, so we put rings Inside sewn in. This should give the proper shape around the mast

    With two sails instead of one, we have the ability to split the sail apart
    The split happens directly aft of the mast, and close to the carbon rings.

    The top gaff as on the Wharram Sail would be carbon instead of wood.
    Square top.

    So the mast is rotating free standing
    The sail is a square top which is already
    Close to Wharrams shape anyway

    Only thing I’m really adding is the
    Rings, and a seam to allow the sail to open

    Only question I have is downwind
    How would a pair of high performance square top sails work wing to wing on whiskers poles?
     
  2. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    Two words: Barber haulers.

    It's a trimaran, so take advantage of that. On my trimaran, I have turning blocks for the Barber haulers mounted on the amas. When the jib is let out on a reach, they let me trim it as flat as if it was on a beat. The Ljungström sail can be similarly sheeted to the amas when going downwind. This can be done with Barber haulers that are always on the two sheets. Or it can be done by routing the sheets through snatch blocks on the amas when the sail is split. The Barber haulers have the advantage that the sheeting point can be continuously varied between the vaka and the ama. The snatch block approach has the advantage that you don't have the Barber haulers banging around and laying on the nets as a trip hazard when they are not in use.

    If you want to adapt the sheeting points for a reefed sail, the turning blocks can be mounted on tracks, just like jibs. That goes for sheeting to the vaka as well as the snatch blocks on the amas. Another approach for upwind sailing would be to have a Barber hauler on the centerline that would pull down and forward on the sheets when reefed, so the sheeting point has the right angle. This allows the sheeting point to be effectively located in space (like over the cockpit) if it's not convenient to have a track there.
     
    Newickspark and BlueBell like this.
  3. Newickspark
    Joined: Jun 2019
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    Newickspark Junior Member

    Thank you for taking the time for these suggestions. I will be researching all
    Of this info.

    I’ll post Again after i learn a little more.

    Much appreciated
     
  4. Newickspark
    Joined: Jun 2019
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    Newickspark Junior Member

    “The Barber haulers have the advantage that the sheeting point can be continuously varied between the vaka and the ama”

    After research. I like this idea best, adjustment is always better. A Negative.... trip hazard.
    Can these be made to dismount when not in use?

    Also I have another idea you could shed some light on?

    When the twin sails need to be tight together,
    Would it be a benefit If the battens could line up and attach to each other?

    I have designed a way for this to work. Carbon fiber battens, sewn into the sail, that attach to each other.

    This idea works, the problem I’m having trouble with, how do I get the battens of the two sails to line up with each other In different wind conditions?

    If two sails are sheeted together, how hard would it be with the proper sail material, to get those battens to line up close? Could a tension system keep the battens aligned close to each other when the sails come together?

    Example:

    I’m running in butterfly mode, ha!
    I now need the two sails to close up while begin sheeted in. These battens need to
    Line up on both sails, attach, which creates one main.
     
    Last edited: Jun 19, 2019
  5. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    If you want to experiment with the rig go buy a Hobie Adventure Island. It already has the square top, roll around, boomless sail you need. To convert it to a double sided sail all you need is a second sail sewn onto the sock. There are also boom conversions.

     
  6. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    I would like to see some diagrams of the idea, .the wings wrap/furl around the mast, are the interlocking carbon battens still acting as a whisker pole(s)?
    The more Newick trimarans in the world the better still..ha. I'm suggesting the first few rings need to have some give [like rubber], the lowest one would have the most stretch to help stop the wear and load on the seam and sail material.They would be sitting atop of the mast when not required and could be pulled down to any height via a halyard ...so the sail can't furl only snuff. Telescopic whisker poles could help shape and work with reefing. The main issue is still reefing, sail shape runs a close second I reckon..
    Thinking about it more if the two wings are put together you have a conventional sail plan and reaching ability. Could there be provision for a barber haul right around the perimeter of the boat like a life line? it may help clear the deck.,[3..ha] cheers,
     
    Last edited: Jun 23, 2019
  7. redreuben
    Joined: Jan 2009
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    Location: Beaconsfield Western Australia

    redreuben redreuben

    one word; Spinnaker

    In a sock.
    Will sail much shyer than your split main which will only sail a few degrees either side of square and limit you to windspeed.
    If a furling asymmetric on a pole is too intimidating/expensive, even a used symmetric in a sock will outperform the split main.
     
  8. tspeer
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    On my boat, I've simply used steel rings attached to the Barber haulers, so they are on the jib sheets all the time. But you could use snatch blocks. They would let you attach them when desired. I've gone with snatch blocks on the twingers for the kite sheets, since the kite is used so infrequently.

    The trip hazard is real, but not all that bad. You just have to make sure to lift your feet when traversing the nets. And when I do trip, I just land on the net, so no harm done.
     
  9. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    First of all, what battens? This is a Ljungström sail, right? There are no battens because the sail needs to wrap around the mast to reef it. Chordwise tension in the sail is maintained by a hollow leech instead of battens.

    If you do have battens, I don't see any reason why they would need to line up with each other. Not even the two leeches will quite line up with each other because the arc length of the cambered double surface sail is different on the windward and leeward sides.
     
  10. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    Each panel of the Ljungström sail is really no different from any other boomless sail, like a jib or a boomless mainsail. I suggest you get with a friend that has a trimaran and experiment with rigging on their boat. You can attach turning blocks to the beams, chain plates, or net attachments. If you're using attachment points that aren't designed for high loads, just be careful and do your experiments in modest winds. If there's no attachment point where you need it, rig a bridle to stronger points. For example, you might tie a line between the forward and aft beams at the ama and then use a rolling hitch or Prusik knot to tie a Barber hauler turning block to the bridle. You can slide the rolling hitch along the bridle to put the turning block wherever you want. Just be aware that the loads at the ends of such a bridle can be quite high if the angle of the bridle at the turning block is shallow, so it's better to provide lots of slack in bridle.

    Then use a snatch block on a line as a Barber hauler, led through the turning block on the bridle to a secondary winch or mooring cleat. In lieu of the snatch block, just tie a loop in the line with a bowline as a temporary measure. Ease the sheet, trim the Barber hauler, and sheet on again. You can use the jib as a surrogate for your Ljungström sail, or even detach the mainsail from the boom to play with it as half of a Ljungström sail. Chances are, the necessary hardware and spare rope is already on the boat in one form or another, so it won't cost you anything. You'll learn a great deal in an afternoon of messing about with the boat.
     
  11. Newickspark
    Joined: Jun 2019
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    Newickspark Junior Member


    Thanks for your time

    I just want to let everyone know I have changed my build plans.

    I’m going build an E25 HarryProa

    Much easier for my first build
    Much less expensive
    Much faster build
    And it can be built to support my camping
    Tent setup much easier.

    It’s going to be used to hop around the Bahamas for a few months.

    Thanks
     
  12. peterbike
    Joined: Dec 2017
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    Location: melbourne

    peterbike Junior Member

    Ah-ha, good choice. :cool:
    We all like to see a happy ending to the story !
     
  13. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    Sure do! Thanks for suggesting he have a look at Intelligent Infusion and harryproas on the other thread.
     

  14. peterbike
    Joined: Dec 2017
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    Location: melbourne

    peterbike Junior Member

    Ahh.., Rob,
    is my commission in the mail ? ;)
     
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