Sprit, gaff, bermudan, lateen sail experiment.

Discussion in 'Hydrodynamics and Aerodynamics' started by johnhazel, Apr 4, 2015.

  1. johnhazel
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    johnhazel Senior Member

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  2. PAR
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    PAR Yacht Designer/Builder

    This is an old piece and full of inconsistencies and half truths. The conclusions are flawed and the tests, frankly are a joke, so don't put much weight in it. Look at his "results", the gaffer was better to windward than the Bermudian sloop and as we all well know, gaffer's have been kicking Bermudian sloop butt to windward for generations, so his data must be accurate.
     
  3. johnhazel
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    johnhazel Senior Member

    The aspect that caught my attention was that sprit and gaff were sailed with a vang allowing control over twist.

    What are the major inconsistencies you refer to PAR? Half truths?
     
  4. messabout
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    messabout Senior Member

    John I think that par is using some wry humor when speaking of gaffers beating Bermudans to windward.

    There is also some "information" out there that have the crab claw sail besting Bermudans. This I gotta' see. :rolleyes:
     
  5. CT 249
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    CT 249 Senior Member

    "Half truths" may be kind.... some of the claims in that article as so wild that they may be closer to outright lies, and arrogant lies at that.

    Take the claim in the first paragraph that rating rules favour bermudan rigs - it's just wrong. Rating rules allowed gaffers to carry significantly MORE sail than a bermudan rig of the same rating, as a glance at the old CCA rule, for example, proves.

    The second par claims that "solid" gaffers are often compared to "sleek" boats with bermudan rigs. While that may have been true when the article was written it is basically misleading because when the bermudan rig first arrived on the scene, it was used on hulls that were identical or similar to the gaffers.

    Many people had the chance over many years to compare gaff v bermudan rigs on identical or similar hulls. Overwhelmingly, they switched to bermudan rigs for better speed and (as noted in old sources) for better economy and usability in racing boats. There are old books that discuss these reasons, but the authors of the article chose to ignore them and instead implied that people switched to bermudan rigs for dubious reasons.

    Still on the first page we find the bizarre claim that no one had ever fitted one boat with a bermudan rig, one boat with an alternative rig, and sailed them together. No one with the faintest idea of sailboat racing history can believe such rubbish. There is no way to count the number of classes that have allowed two rigs on the same hull to race against each other. It's happened over the decades in major classes like Stars and the former Olympic Sharpie, Mirrors as well as in smaller classes such as some NYYC one designs, Redwings and many others. Something identical, or very similar, occurred in 6, 8, 12 and 23 Metres, International 14s, skiffs, racing canoes and probably hundreds of other classes.

    The claim that opinion about the merits of each rig is based on "hearsay and very subjective comparisons" is equally insulting and objectionable, since this was something that mattered very much to sailors of an earlier era. The authors apparently believed that the thousands of sailors who switched from gaff and gunter to bermudan in Australian Sharpies and skiffs, Int 14s, Metre boats, Stars, offshore racers etc were somehow incapable of watching the rig experiments happening before their very eyes.... Anyone who does any research knows that they DID watch, discuss and analyse such things in depth and detail.

    So enough of the yawning gaps in the first part of the article - what about the numbers? Well, the claim says that a sprit is 30% better upwind. So apparently a 470 with a sprit rig could beat a Hobie 16 and International 14 upwind. A J/24 with a sprit rig could beat a Farr 40 OD and be on a par with a Farrier 25, a fast racing tri. A Laser with a sprit rig could beat all the lightweight singlehanded skiffs, with racks and trapezes, upwind.

    Oh, what ****** the sailors of the world have been - why did the C Class sailors waste time with wing sails, when they could just have put a sprit on a Hobie 16 and gone even faster?

    Apparently the lateen rig is also 30% slower than the bermudan rig upwind- so if we put a Bermudan rig on the Sunfish, it would beat a Hobie 16 upwind. If we put a sprit rig on a Sunfish and got the extra 30% upwind boost, the Sunfish would leave the foiling Moths a lap behind! How could the Mothies be so silly as to waste all their time when they could just whack a big Opti rig on a Sunfish and go even faster than they do with their carbon foilers?

    Of course, we know the numbers wouldn't simply scale that way, but they show that the performance claims are utterly beyond the point of even being ludicrous.

    Even more mysterious - since so many of the world's sailors came from classes like the Opti, Mirrors and Sunfish, which have sprit, gaff/gunter and lateen rigs, why did they happily switch to the supposedly inferior bermudan rig when they got older?

    The article is beyond flawed and should never have been published as is, IMHO.
     
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  6. PAR
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    PAR Yacht Designer/Builder

    I remember the piece when it was first published and it was widely criticized at the time and is more so now. The conclusions, inconsistencies and flaws are obvious John, particularly in light of the nearly half a century of sail evolution, since this fantasy was written.
     
  7. johnhazel
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    johnhazel Senior Member

    :) Yep

    So do you remember who the author is and what his affiliation to any marketing that might benefit from the conclusions?
     
  8. PAR
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    PAR Yacht Designer/Builder

    No I don't remember the author, but his predisposition is obvious and his conclusions simple unverifiable by even the wildest reasonable set of tests or observations. I think the publishers knew his "views" where a bit out there and the fact the author wasn't published, is a real good indication of what he or they really felt about the piece.
     
  9. sharpii2
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    sharpii2 Senior Member

    I wonder if they ever took balance into account. It appears that the CA of the Lateen rig is much further aft than that of the other two.

    Is it possible that the sprit sail rig sailed better simply because it had the best balance?
     
  10. DCockey
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    DCockey Senior Member

    The tests are described as having been carried out by "Gifford Technology of Southampton". My recollection the reseach dates from the 1980's, and that Tony Marchaj did some wind tunnel tests. The comparison of sail types is discussed in one of Marchaj's books.
     
  11. PAR
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    The basic premise is flawed, as they used several different hull forms to make these comparisons, which is simply inappropriate testing and can provide no useful information, except possibly that some hull form might have better results than others, with various rigs. I don't remember Marchaj being involved in this and I'd think this would have been a notable mention, in the piece. I also remember it in the 70's, not the 80's, though I'm guessing really. Hell, I can't remember what I did last week. As far as wind tunnel testing is concerned, we've done these tests repeatedly over the decades and this configurations have offered no new surprises, though the WoodenBoat or Sail Magazine piece (can't remember which) in the early 90's surprised everyone with the crab claw, it too had it's draw backs to consider, compared to a conventionally designed, fractional Bermudian sloop. What really needs to be done is to get a J-24 and rig it with all the contrivances they can think of in regard to rig types and of course several times around a fixed set of buoys. We'll see how the crab claw holds up and how much better the gaffer is, compared to a flat topped Bermudan.
     
  12. johnhazel
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    johnhazel Senior Member

    On the contrary they claim to have used two identical catamaran hulls and sailed them together. One hull kept the bermuda and the used in turn each alternate sail rig.

    They should have put the bermuda on the second boat and tried one of the alternates on the first. An easy explanation for their bizzare results is that the bermuda rig hull was not clean compared to the boat used for the alternate rigs.
     
  13. johnhazel
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    johnhazel Senior Member

    And they are still making the claim!
    http://www.christinedemerchant.com/sail_sprit_sail.html


    EDIT:
    Oops to be fair one of the lines in that web page says the pointing ability of thier sprit sail is not as good as the bermuda:
    The sprit sail compares favourably with more modern rigs in all points of sail except when pointing upwind. It matches speed while going downwind.
     
    Last edited: Apr 7, 2015
  14. DCockey
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    DCockey Senior Member

    Marchaj's Sail Performance (1990/1996, McGraw-Hill International Marine) has Chapter 11 titled "The Sail Power of Various Rigs", which appears to be based on wind tunnel test by Marchaj "on the potential power of a number of rigs: Bermudian, latten, sprit, gunter, dipping lug and crab claw .... used to drive small fishing vessels". (p152) A considerable portion of the chapter is focused on crab claw sails, with claims of superiority over other rigs.
     

  15. johnhazel
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    johnhazel Senior Member

    Yes I have read that. I have not seen any side by side comparisons with this and other rigs in actual use. It seems there must have been tests for the reasons alluded to by CT 249. If the benefits were real, many more boats would be using it.
     
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