Lateen sails

Discussion in 'Sailboats' started by velelatine, Nov 12, 2006.

  1. Guillermo
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    Guillermo Ingeniero Naval

    Hi, Enrico!
    Interesting site.
    Very funny the 'Itanglish' translation!
    Cheers!
     
  2. Guillermo
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    Guillermo Ingeniero Naval

    Here a better drawing of the Portuguese "Muleta do Seixal" (1st image) and another one from its close cousin the "Bote da Arte da Tarantanha" (2nd image). Both were used only in Barreiro, Seixal and Cascais, all three villages close to Lisbon. They were used in side trawl fishing, using a net called "tarantanha".
    The third one is also a muleta but only used in Cascais (Muleta de Arrastro).
    Look at the complexity of those rigs.
    Any of you interested in knowing more about traditional portuguese boats, visit:
    http://www.ancruzeiros.pt/ancbtradicionais.html
    Cheers
     

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  3. velelatine
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    velelatine Junior Member

    Video: Lateen Sail National Championship 2004 :D

    Video (235 mb)
     
  4. sharpii2
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    sharpii2 Senior Member

    Are you saying the thing was sailed sideways with the nets down?

    Bob
     
  5. Vega
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    Vega Senior Member

    yes, that's the reason for such a sail area.
     
  6. Guillermo
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    Guillermo Ingeniero Naval

    Beautiful!
     
  7. velelatine
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    velelatine Junior Member

    Tnx Guillermo ;)
     
  8. CapKos
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    CapKos Junior Member

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  9. sharpii2
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    sharpii2 Senior Member

    Certainly. But it may not be practical (as opossed to using other rigs)

    The big problem is that your 32 ft boat is going to need from 400 to 500 sft or more of sail area. Since, with the classic lateen sail, the yard is on the longest side of a right triangle, the yard has to be very long (42.5 ft for a 450 sft rig).

    This long yard now is suspended from a mast and has to be able to swing about it suspension point as well as go up and down. This can make it very difficult to control and, because of its great size, dangerous.

    There are, however, ways of getting around this problem.

    One is to add a boom to the rig. By controlling the swing of the boom, you are also controlling the swing of the yard as well.

    Once a boom is added, the length of the yard can be shortened and the foot of the sail can be lengthened. Now the yard is not only under much better control, but is shorter (31 ft as to 42.5 ft) and lighter as well.

    Not only that, but the yard can now be pitched much more verically, because it now mostly acounts for just one dimension (the hieght) of the sail area, not two (the hieght and width). This is the familliar 'Sunfish(r)' rig, an absolutely wonderful beginner rig.

    Now your major problem is reefing.

    Every time you take out a pie shaped section out of the sail, you change the pitch of the yard and the boom. To fix this, you need a new hoisting/swing point on either the mast or the boom. Imagine having to do this in squally weather with your boat's side to the sea.

    A quick and dirty solution to this problem ios to add a rectangular section of sail between the boom and the yard. This makes it a settee sail. By reefing just that rectangular section, you can maintain the old pitch of the yard and boom.

    I am considering such a rig myself. It will have a vertical leech, a yard set at 45 deg., and a rectangular section that has half the hieght of the triangular section. This way, the boom and yard are kept short and half the sail area is easily reefable.

    For our hypothetical 32 footer, that would mean a 30 ft yard and a 21.5 ft boom. This may be workable.

    Bob
     
  10. CapKos
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    CapKos Junior Member

    Hi Bob,
    Thanks for the nice explanation. I suppose that the extreme exploration of this idea is the gaff rig. I like lateen sail because of the lower working point, which help shallow draft. It is possible also to lighten the boat to some extend and have more cargo. I figured a possible sail plan with 11.3 m yard (37 ft) plus a jib. The effective area is 48.75 sqm (524 sqft). This boat will have CE of about 4 ft lower then similar Bermudian rigged boat. Additionally the sailing area could be increased with topsail with about 8sqm, (86 sqft). 37 ft for the yard is a lot, but I suppose that with the new materials is possible to make a lighter and stronger yard, then 500 years ago.

    I would like any input on this sketch.

    CapKos
     
  11. CapKos
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    CapKos Junior Member

    Oups, here is the sketch
     

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  12. sharpii2
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    sharpii2 Senior Member

    I like your sketch.

    There are, however, two problems that I can see.

    1.) Your Center of Effort is drawn way forward of where it most likely will end up. Loose footed jibs tend to have thier Center of Efforts further aft than boom footed sails. Since it appears that your lateen sail is loose footed as well, There would be even more reasons to move the estimated Center of effort aft.

    2.) Your jib seems to be a bit large. In order for it to stand well, shrouds and stays will most likely be needed to maintain the luff tension. Having these will most likely make sheeting and handling the 37 ft yard interesting.

    I do agree that a higher tech yard can probably be built that is lighter than what has traditionaly been used. One must keep in mind, however, that the ancients were very well aware of the weight problem themselves and took care to use the lightest wood available. I wouldn't bet on reducing its weight by more than 50%. And spending up to 50% of the cost of the boat doing it.

    From looking at your sketch, I am reminded of a gaff cutter. Imagine cutting the long yard in two, putting jaws on the aft end and making it into a long gaff (Joshua Slocum's famous Spray had a gaff of similar length), then puting a short jib where the forward part of the lateen used to be. Doing this will allow the rig to keep its low Center of effort, make the boat much more 'user friendly' and, perhaps, more suitable for its intended purpose.

    This design becomes almost a history lesson on probably how and why the lateen sail was replaced with the gaff rig.

    Other than that, I'd move the lateen forward, make the jib smaller, and buy a good (but not neccessarily powerful) engine for light air work. Due to handling issues with a lateen sail (the classical version), I would be tempted to keep the sail area on the short side. Especially if I had to go with a small crew.

    Bob
     
  13. CapKos
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    CapKos Junior Member

    You are right on both points. The center of effort is verry aft and the latten sail didn’t help. In the positive side a costal cruiser with reliable engine is probably not so bad, since most of the sailors on Mediterranean actually motoring most of the time. BTW aren’t old pirates on Mediterranean mostly rowing? By now standards this could be named motor-sailing. For offshore work however the more robust gaff rig is better.

    All the best,
    CapKos
     
  14. sharpii2
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    sharpii2 Senior Member

    Just for your entertainment, I decided to scan some drawins of mine to show my idea of what a modern boomed lateen and boomed setee might look like. Both are drawn to traditional proportions except that the setee is coming close to being a ballaned lug because of the amount of sail under the triangle.

    One of the bigest advantages of this type of rig is that the mast can be so short that it can be made much stronger than usual. The long yard may break, but it may be brought down to the deck to be repaired much easier than a broken mast can be.

    One option, in your case, that I failed to mention, is stepping a long but light top mast above the original rig that can fly a relatively large topsail for light air work. If this mast is damaged or destroyed the boat will not be disabled.

    So here's my pics.

    Enjoy.

    Bob
     

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  15. CapKos
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    CapKos Junior Member

    Hi Bob,
    Thanks for the sketches. I guess that the boat with the setee will be a fine cruiser. How big is this boat? An advantage of shorter mast is that it can go down bridges. Air clearness less then 7 m will be able to sail most of European internal waters, which is a big fun. I suppose that such a boat will fit 90% of the sailing programs, now days. It is a pity that it is not very common :confused:.

    All the best,
    CapKos
     
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