Crab claw sails evolving to rectangular shape

Discussion in 'Sailboats' started by gonzo, Nov 28, 2020.

  1. BobBill
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    BobBill Senior Member

    Who really can pinpoint with certainty, save one thing...practicality...the need to do...with facility.
    As with so many things...the words of CSNY come to mind, "everybody's right and everybody's wrong!"
    But, stirs the mix.
     
  2. Will Gilmore
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    Will Gilmore Senior Member

    Even 'practicality', like 'efficiency' is a relative term and filled with variations and factors such as, availible knowledge, availible materials, time and effort to aquire better technology as well as community support.

    It may be that following tradition is the easier, more practical path than adopting faster, lighter, stronger, higher pointing sails for reasons outside of sailing.

    -Will (Dragonfly)
     
  3. BobBill
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    BobBill Senior Member

    Whatever gets the job done, no doubt, is theory and what most of us do...
    jury-riggers that we might all be.

    Will. Have to ask, Dragonfly is a name given or a design like White's Dragonfly, which is a wonder and one of ideas for my very own craft...
     
  4. Will Gilmore
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    Will Gilmore Senior Member

    20161003_162016-1.jpg 20170815_225742.jpg
    It is the name of my boat. I started using it, along with my sail number, because that seemed to be the protocol when I joined the Mariner Class Association. I later joined Sailboatowners.com and dropped the sail number. I've just continued using it over here. I've thought about dropping the boat name, but this is a boat forum, so the habit seems to fit, although I think I'm the only one who does it.

    That's Dragonfly at the top and the new hatch boards I made and burned a rose for my wife, a Dragonfly for the boat, and a dolphin for me.

    -Will (Dragonfly)
     
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  5. BobBill
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    BobBill Senior Member

    Will, Thanks..

    Sold a 'keeler' to an acquaintance who had DS rig. His was a centerboard version and I guess had ballast, as I recall.

    Well, either way, the ballast shifted and he and wife got wet...so he bought my keeler (O'Day Rainbow???)---larger with lead keel. Worked well for me; I did not dig the " R'Bow" much.

    Whites' Dragonfly is stayed and shown on line as a "Tacking 'Proa'," which upsets some shunting proa sailors, for some reason. Figure "proa" means "boat"...words.

    With its unplanned-for stays, my Malibu Outrigger does resemble Whites, but does not have his fully-battened orig sail plan. My MO uses the more original MO-gaff plan...

    FWIW, dragonfly-insects have fascinated me for decades...even make them with copper/brass scrap - garden art. One sits atop our mailbox post.
     
    Last edited: Dec 16, 2020
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  6. gonzo
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    gonzo Senior Member

    Back to the subject of this thread. There are several proponents of the crab claw sail that claim it is more efficient than a modern shape. However, the locals seem to use other shapes when the materials allow them to.
     
  7. CT249
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    CT249 Senior Member

    And (like fans of many other rigs) the proponents of the crab claw sail manage to spend far more time saying how good the sails are than they do actually trying to prove it in any quantitative measure.

    Of interest, years ago there was an annual race in Port Moresby between New Guinea canoes, Fireball dinghies, Hobie 16s etc. The accounts I have indicate that the far smaller western boats were faster around the reaching course by a long way, although at times the much bigger double canoes could perform well.

    It's also interesting to read some old accounts (late 19th/early 2oth century) of proas etc and see how respectfully western sailors treated them, the skill of their sailors, and their performance. The claim that there was racist prejudice against them is not substantiated by any material I've seen, apart from the terms used to describe the sailors. The same thing applies to the Malayan canoes and other indigenous craft - they were treated with great respect by western observers. There seems to be no basis to any claim that these craft and their rig would have been rejected by conservative westerners; they just did not do what the westerners wanted to do as well as western rigs did it.
     
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  8. Rumars
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    Rumars Senior Member

    Every claim about the superiority of crab claws can be traced to the writings of Marchaj. The problem is that nobody could reproduce his results and validate them.
    Don't get me wrong, the crab claw is not a bad sail, but it's not "superior". It has some interesting advantages, for example the ability to vary the CoE not only fore-n-aft but also sideways, wich can be a big help on a traditional proa. It also has disadvantages, like hard to reef and ungainly in bigger sizes.
    "Efficiency" is also a matter of interpretation. Aerodynamically, the rigid wingsail is best. Square riggers can put the most sail area on a given height mast. Junk rigs are the easiest in operation. Defining "efficiency" is part of the equation, otherwise we compare apples to potatoes.

    As for the "locals" using other forms of sail, we need to be more specific. Oceanic lateens are still used, but sailing, and especially big boat sailing is not exactly common anymore. Some areas still maintain tradition but most oceanic lateens are used on small craft, a 60ft proa is rare, and 100ft+ boats are historic. Crew sizes are not exactly at historic levels either, and the experience in maneuvering the big rigs is lacking. Add the fragility and cost of the rigs made from natural fibers and it's easy to understand why other rig forms are also used on "delivery".
     
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  9. Will Gilmore
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    Will Gilmore Senior Member

    So true about "Efficiency". It's all relative to need or intent.

    As for the relative efficiency of the crab claw vs the Marconi rig, for example. In my research into the Crab Claw, I found a much more varied configuration of rigs being called crab claw, than the traditional Pacific Islands Oceanic Lateen rig. I even found rigid winged sails similar to the sail on the sailrocket that were considered by some to be a crab claw.
    From Wikipedia:
    upload_2020-12-17_23-33-28.png
    "Traditional Austronesian generalized sail types. C, D, E, and F are types of crab-claw sails.[1]
    1. Double sprit (Sri Lanka)
    2. Common sprit (Philippines)
    3. Oceanic sprit (Tahiti)
    4. Oceanic sprit (Marquesas)
    5. Oceanic sprit (Philippines)
    6. Crane sprit (Marshall Islands)
    7. Rectangular boom lug (Maluku Islands)
    8. Square boom lug (Gulf of Thailand)
    9. Trapezial boom lug (Vietnam)"
    From https://www.simplicityboats.com/crabclaw2.html
    upload_2020-12-17_23-37-3.png

    If the definition of crab claw is something as vague and broadly applied, it certainly could be argued in favor of the crab claw. Just as a rigid wing sail supported in the middle and made square in profile, pivoting on a mast so it can be positioned horizontal like a yard of a tall ship or rotated vertical to sail fore and aft, could be called a square sail that sails upwind. Could it truly be claimed that one rig is inherently more or less efficient than another if there is some undiscovered variation that may become the next fastest sailboat on record.
    upload_2020-12-17_23-47-10.png

    -Will (Dragonfly)
     
  10. BobBill
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    BobBill Senior Member

    "Efficiency," as relative term...maybe the "relative" refers to "gets the job done?" Which, to me, opens another can of worms,
    work versus play, that is, fishing, transporting, etc, versus leisurely sails and racing, (transit time(s) notwithstanding.
     
  11. gonzo
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    gonzo Senior Member

    It's not a can of worms. Efficiency has to be related to a property or set of properties. In this case , I think that it would be thrust generated by sail area. It would further be divided by point of sail (wind angle).
     
  12. Will Gilmore
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    Will Gilmore Senior Member

    As BobBill says, it depends on the job and the perspective for doing that job. Gonzo's example is a good definition of the parameters, to move a vessel as fast as possible by the least area of sail at the most points of sail.

    However, there may be cost, ease of operation, ability to respond to a range of weather conditions, comfort, control with a limited crew, changing course with minimal loss of headway, ease of maintenance, least sacrifice of deck space to other tasks, who knows what parameters a particular sailor may use to determine efficiency?

    I'm happy with Gonzo's clearly stated properties. I think the crabclaw can be designed to compete with the Burmuda rig, but we need to nail down the definition of 'crab claw' too. The Burmuda Rig has less variation and has, I think, been developed the furthest for the properties Gonzo stipulates.

    How about, 'equilateral triangular sail between two equal spars that come together at the clew, supported by a separate mast.' Or, would you want to allow for one of the spars to also act as the mast?

    -Will (Dragonfly)
     
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  13. gonzo
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    gonzo Senior Member

    I think that crab claw sails have curved spars. A triangular sail with two spars would be a lateen.
     
  14. Rumars
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    Rumars Senior Member

    There are two "lateens", the "lateen" used in the Med and arab world, wich has only a yard, and the "oceanic lateen", a sail with yard and boom. Like the "normal" or "western" lateen, the oceanic version has many forms, differentiated mainly by aspect ratio, boom to yard angle, and spar length and form. The crab claw is the version with deeply inward curved spars and a semicircular leech.
     

  15. BobBill
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    BobBill Senior Member

    Crab or Lateen

    Crab or Lateen...IMO, whatever works.
     
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