Junk Rigged Trimaran

Discussion in 'Multihulls' started by Owly, Oct 14, 2016.

  1. Owly
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    Owly Senior Member

    I'm interested in anything on cruising trimarans converted to an unstayed mast with a junk rig. So far I've found only one converted to a junk rig, and it's a 3 meter Marples. There several cats with two masts, and they are quite elegant flying wing and wing. Junk rig appeals to me for a number of reasons. Unstayed mast / no standing rigging, balance area on the sail, light sail loadings and sheet loadings, instant reefing, and.....
     
  2. Owly
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    Owly Senior Member

    Oops:
    My links didn't work ;-( I haven't figured out how to past a link to my files on my own computer. Let me try this..........

    H.W.

    /home/howard/sailboat stuff/wing_and_wing_Junk.jpg
     
  3. Owly
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    Owly Senior Member

    sorry about all this experimentation....... I'd edit these attempts out if I could. Looks like my only option is to past links from the net..........

    H.W.
     
  4. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    That's correct -- to use IMG code it has to be on a web accessible space/website. Or you can use the manage attachments feature to upload and attach with a post (click on go advanced or the blue post reply button and then click manage attachments.)
     
  5. cavalier mk2
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    cavalier mk2 Senior Member

    Heads up, even James Wharram decided junk sail weren't good for multihulls because of the increased turbulence caused by higher speeds and closer apparent wind angles. The unsupported luffs tend to shake a lot.
     
  6. Owly
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    Owly Senior Member

    Thanks for the suggestions. I'll try again. A picture is worth a thousand words they say.

    H.W.
     

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  7. Owly
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    Owly Senior Member

    And the other one hopefully ;-)
     

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  8. Owly
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    Owly Senior Member

    The junk rig has come a very long way since Wharram reached that conclusion. The technology has not been standing still by any means, but people are slow to change their conclusions and prejudices. The flat junk sails used by Blondie Hasler, and JK Mcleod are pretty much a thing of the past except for those who don't feel the effort of making properly cambered sails worth the effort. Modern cambered panel junk sails and especially split junk rig sails are capable of taking on a very efficient airfoil shape, and driving upwind with the best Bermuda rigs, and far better downwind, and on a beam or broad reach.
    In my case, the junk rig is a non-negotiable must have as a solo sailor who insists on simple and reliable. Shredding hundred dollar bills while taking a cold salt water shower is not my idea of fun ;-)
    I intend to at least try it.......... If I can't make a junk rig work on a trimaran, then I guess it's a monohull for me!

    H.W.
     

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  9. Richard Woods
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    Richard Woods Woods Designs

    And so of course has the fully battened conventional mainsail. No longer do we have heavy wood battens and a jamming sail track. Even on a 40ft catamaran you should be able to hoist a mainsail pretty much to the top without winching. And single-line reefing into lazy jacks means you can reef a sail singlehanded in seconds (well certainly in under a minute)

    I have seen both Jesters sailing and also Badger, incredibly slow boats. The junk rigged boat I sailed was just about the worst boat I have ever sailed. It wouldn't go to windward (we had to start the engine) reefing was really hard, there were lots of lines in the cockpit. Horrible.

    https://www.youtube.com/watch?v=29QabdOcXwA&index=26&list=PLT7PbPvOm8lzsFDoSIUv_Fumvr_Zquicc

    You have to ask "if the junk rig was so good, so cheap, so easy why does no race boat use it?"

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  10. Owly
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    Owly Senior Member

    Richard:
    Not all of us are interested in racing, or in ultimate performance, nor should current racing technology dictate the way cruising boats are designed or rigged. The fact is that junk rig technology is catching up with the Bermuda rig in more normal boats, but few current junk rigs are built to that level of technology yet. It always takes time for the bleeding edge of technology to filter down to the masses. The bleeding edge Bermuda rig technology is extremely expensive, while the most advanced junk rigs still use pretty simple and inexpensive materials, and the technology is in the cut of the sail panels. Unlike the Bermuda rig, there are only a very few people building the rig, and probably no boat builders manufacturing boats with Junk rig, and perhaps half a dozen experimenters pushing the technology forward actively if slowly. A labor of love, not a profitable commercial endeavor. I don't think anybody in the junk rig circle even remotely considers the rig as a potential racing rig. You're never going to see it in the Ostar or Transat, or America's cup, that's not it's niche. They have many advantages for cruisers and daysailing. Clearly it has no appeal to you...... or to many others.

    Thanks for the link to the Utube video..... I've seen that technology before. While the junk rig is the only rig that really interests me, I do keep up with sailing technology in general. The big difference between what I see in the video and the junk rig, is that each panel is an individual sail in effect on a junk rig. That means that as you drop the sail, one panel at a time, the remaining sail retains it's efficiency, it's shape / camber, and usually the camber is less in the upper panels, so that they function efficiently in higher wind. Sail shape does not depend on tension supplied by the various lines and the vang or kicking strap, it's controlled by the cut of the sail and by the battens. Here are some photos of modern camber panel junk rigs of three different types. Note in the second photo the very distinct and well defined camber in the panels that reduces at the top of the sail. The first and third sails use a different method to achieve camber. The third is an extremely innovative and very high performing rig that has outperformed comparable Bermuda rigs. Note that the split was intended to eliminate the interference of the mast on one tack, but also creates a main and jib, with a slot designed to enhance the performance of the system. This sort of development is the work of a very few passionate builders working on their own to advance the technology. There are a fair number of junk rigged catamarans out there, such as the last photo. Note that most of the sails if not all of them here are built in people's living rooms, backyards, etc, out of inexpensive materials, not by sailmakers out of the latest high tech sailcloth.

    Your arguments against the junk rig are the same I hear everywhere, and they do not sway me at all. It is what I am interested in. I intend to put an unstayed mast and junk rig on a cruising trimaran. I have not picked out the boat yet, but it most likely will be an older "cold molded" plywood design. The mast has to be able to be located forward of the original position to keep the center of effort approximately the same. The balance percentage of the sail, that part forward of the mast, is a flexible percentage from about 10% up to about 35%, which gives some leeway. I would also like to install a small mizzen near or at the transom as a tool for balance, etc. As far as doing this on a trimaran, it looks like I'm pretty much on my own. I won't go into the reasons I want a trimaran, as they have no doubt been discussed to death here already. Racing is NOT one of them.

    H.W.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  11. Richard Woods
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    Richard Woods Woods Designs

    You misunderstood me. You said "...and driving upwind with the best Bermuda rigs..."

    Which to me meant rigs used on racing boats - which exclusively use the "best Bermudian rigs". Thus your comment implies you think the junk rig is as fast as a bermudian rig.

    therefore my comment "why don't racing boats use them?" is reasonable

    Even if you yourself don't want to race you probably want to get off a leeshore in a gale, or get home before the pub closes, or get past a tidal gate.

    There are very few people who actually want a slow boat. Most want a boat that is easy to sail and has a predictable behaviour. You don't have to have a junk rig to get that

    RW
     
  12. cavalier mk2
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    cavalier mk2 Senior Member

    I'll stay with Richard on this one but it's nice to see someone trying something. Those pictures certainly look corrugated with vertical camber between battens and double horizontal camber induced by the mast. This makes things less efficient for a given amount of sail area, low area with easily driven hulls means less work sailing.

    My suggestion for the junk rig would be to go with wishbone battens and sail cloth on both sides of the mast for a true foil shape with the advantages of junk rig control.

    Freestanding masts in tris are nothing new. Newick designed cruisers that way using a rotating lungstrom rig.
    The advantage there is the sail can roll up on the mast for reefing and being a double sail it allows you to open it up to double the off wind area.

    Far less expensive to get that donor monohull though, plus with that displacement wave train you'll seem just as fast as the conventional rig in a breeze. Light air sails are a bit of a head scratcher with a junk but I imagine something with a free luff could be hoisted to the masthead.
     
  13. Richard Woods
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    Richard Woods Woods Designs

    Of course doubling the sail cloth area will hugely increase the price of the sail and the weight you must lift when hoisting

    All the junk rig sailors I have met and read about complain that the sail slaps and bangs in light winds. Pitching can't be good either with all that weight aloft

    RW
     
  14. cavalier mk2
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    cavalier mk2 Senior Member

    This is true. For low cost and simplicity it is hard to beat a conventional sloop rig with a furler jib. Monohull gear and sails are readily available 2nd hand and light air sails are easy to rig. Conventional main reefing is easy, even if you skip battens. We cruise this way, the boat sails very well and handles fast changing conditions easily.

    Our late season cruise took us into the Central Johnstone Straight area and we didn't return till late September, easily shortened or increased sail area keeps it fun. In the PNW good windward ability is important as most of the time you are either going to windward or downwind because the islands and mountains channel the wind. Going up we had some great tailwinds where the chute would be up all day, great to be able to take advantage of the speed to cover more ground. If you can't sail well to windward you'll use lots of gas.
     

  15. Richard Woods
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    Richard Woods Woods Designs

    There are lots of ocean cruisers new to sailing who say "I'll go where the wind blows".

    What they don't realise is that means they eventually end up on a lee shore - then what?

    Cav, I didn't do much sailing this year in the PNW, apart from the R2Ak, I write this at home in the UK

    RW
     
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