Reefing a lanteen sail

Discussion in 'Sailboats' started by science abuse, Aug 23, 2011.

  1. Pericles
    Joined: Sep 2006
    Posts: 2,009
    Likes: 135, Points: 63, Legacy Rep: 1307
    Location: Heights of High Wycombe, not far from River Thames

    Pericles Senior Member

  2. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 99, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Excellent reply, thanks. The boomed lateen is obviously the right rig for some uses and has its very good points I had never thought about as I haven't sailed one since 1967 on Kure Island.
    It's NINA, not PINTA I was skipper of. We tried everything to go to windward and found that we could make good slightly above a reach, so 150-160 degrees between tacks. This was somewhat a function of the ship always being light and never loaded down. With 50-60 tons aboard she would have done somewhat better. Rigging bowlines would have helped too, but the replica does not have them as her rig is somewhat simplified for ease of handling in her actual use, which is a dockside attraction vessel.
    Hard to tell if anyone is right about lateen as it was little documented, but the theory of changing ends on the yard seems far-fetched, as a timber yard is quite a bit heavier on the lower end due to snotter (tack) tackle loading, and your theory gives no advantage in handling that I can see, requires a symmetrical sail and yard and does not seem practical.
    Went and looked up the lateen use among the ancients and Lionel Casson (The Ancient Mariners, Princeton, 2nd edition 1991) says that the true lateen and the settee lateen with a short luff were both used, but you're right that the grain ships were square rigged forward, though no definitive proof has been found, and they may have set lateen mizzens.
    The large 13th century lateen with a forward raking mast made me start wondering about your ideas. Here is a San Francisco Felucca which used that rig and they dipped the yard around the front of the mast by pulling the yard vertical and taking the sheet around the front and usually jibed instead of tacking. With no shrouds, this is easy. With shrouds, the yard must be slung outside the shrouds for this to work, and not between shrouds and mast like NINA, and this causes chafe issues. With very large yards, I doubt they were ever dipped and were hoisted inside the shrouds. One reason for forward leaning mast is it gets the sail area forward while keeping mast weight and strain back in the wider and stronger part of ship.
    Here's an interesting historic link about lateens in (hotly debated) history.
    http://books.google.com/books?id=Ww...cQ6AEwAQ#v=onepage&q=dipping a lateen&f=false
    Excellent discussion and I'm sorry I was so passionate since you make a very thoughtful argument and really think about things.
    Reason for dipping lug being good was great power to windward, very cheap, leaves boat open for fishing, very cheap, oh, and cheap since no jaws, boom, hoops, second halyard, shrouds etc. Luggers used mostly in areas of steady winds and where not much tacking was required. Places like Polperro with the wind blowing right in the harbor, used gaff rigs so they could beat out. The 18' lapstrake boat I had with a dipping lug and 1000 pounds of stone ballast could outpoint a Cal 20 if he did not have new sails. Very weatherly and strong pulling, but not right for most boats.
    All square sails have gear to pull them up to the yard, what you refer to as brails. Older ones used removable sections from the bottom, the "bonnet" and the "drabbler" to reduce area. GOLDEN HIND (English, North Atlantic) had no reef points and did not reduce sail from the top in 1579. NINA has no ratlines, no footropes, no reef points and sail is either set or not, being gathered by the leeches and the martinets. The square sail revolution happened in the 1600s and most modern gear was in recognizable form by 1750, ratlines, reef points, buntlines, leechlines etc.
    Mystic Seaport does focus on east coast US vessels, but the library has incredible resources and when I was a rigger there we were required to spend 4 hours a week researching and I read widely about the ancients once the MORGAN and such got boring.
     

    Attached Files:

  3. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Thank you Pericles!

    Damn. Quite a hot race they had going.

    I also noticed how high up the mast intersected the boom. Clearly better for dipping.

    I also noticed that the lower end of the yard stayed fixed to the stem of the boat with the yard acting almost as a rigid head stay.
     
  4. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Thanks, Bataan.

    A good read.

    Still doesn't solve the forward sloping mast question.

    In order to dip the long yard, you would have cant it way past vertical. Far better, wouldn't you agree, to rake the mast aft some. If I were designing one today, that's what I would do.

    That's why I came to my 'wear ship' hypothesis. Then, raking the mast forward would make more sense. Reading the link you posted, make me all the more suspicious that I may have been right. If you have a slow, lumbering vessel, rounding up through the wind seems a bit risky. Even my Siren 17 had trouble. It was so unreliable at doing that, I quickly learned to back the jib every time I changed tacks. I only got that idea from reading Earnest K. Gann and Howard Chapelle. I don't know if that would work with a large lateen rig.

    Did you have to back wind the Pinta when coming about?

    Any rate, my guess is the method I proposed was quickly abandoned (after, perhaps, a century or two) but the old staying geometry was kept.

    It is quite clear that dipping is the best way to change tacks with this rig. The question is how long did it take them to figure that out.
     
  5. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 99, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    The sloping mast means yard has to go only vertical, not past, and lateen always prefers to gybe if there is room, just like a square rig. In this setup the halyard tye goes from aft to fwd through the masthead "Calcet" block and the yard does a vertical pirouette as the sheet is passed around the fwd side of the mast, with a slack snotter, gets on the other side, the snotter is tightened and the sheet taken aft. Requires manpower. When dipping behind the mast and inside the shrouds the tye goes from fwd to aft. What you describe is a short dumpy small squaresail with two corners cut off to make an even smaller triangular sail that can be set with either end of the yard pulled down, or horizontal, the size limited by the distance from Calcet to deck. This is a small sail unless the mast is long, vertical and far back from the bow if you draw it out and the geometry is limited by making is symmetrical. The question is where did this come from as there are no records, pictures, engravings, accounts or stone petroglyphs of such a thing but are of others.
    Lateen has a definite shorter lower heavy section set on a shortish mast and long light upper, this is its advantage, a large high fore and aft sail that can take the wind on either side without tacking at all. Square always has the wind on the back side but fore and aft takes the wind on each side alternately so they are fundamentally different.
    Here is a brief article.
    http://en.wikipedia.org/wiki/Lateen
    And another that endorses it as you do.
    http://www.duckworksmagazine.com/09/columns/austin/02/index.htm
     
  6. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 99, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    A lateen running off the wind and one tacking with the sail aback.
     

    Attached Files:

  7. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Actually, I just took a flying guess.

    All the pictures of engravings I have seen have been damningly vague. Some of them you can't even be sure your seeing a lateen at all. None of them that I have seen show the running rigging at all (artists, after all, are not engineers).

    The great temptation is to take what there is a lot of records on, the ships of the high Byzantine era, and extrapolate back from there. Clearly, if the yard is going to be longer above the mast than below, the lower part of the yard should be thicker, as it is taking a point bending load, whereas the upper yard is taking a distributed one.

    With the system I propose, this would be less true.

    Also, with my system, the length of the yard can be can be twice the distance of the Calcet to the stem, as the yard is never expected to go vertical, but no more. To get more sail area, the mast would have to be taller. And you have to wear ship every time you change tacks.

    This disadvantage may be mitigated somewhat, as with the yard parallel to the waterline, this set up could be quite stable going down wind.

    In order to give more credence to my theory, I will have to build a working model at least big enough to go on a small manned boat and put it through its paces, which would have to include squally weather.

    Maybe I'll draw some scaled sketches, just to see what the mast to yard proportions have to be and post it.

    probably nine chances out of ten, I'm wrong. And even if I'm right, the only evidence may be a successful working model. Notes on early lateen design, if they ever existed at all, probably perished when the great library of Alexandria burned the first time.

    My guess is they didn't even exist before then.

    Seafaring was not a trade highly regarded by the Romans. They did it, of course. But only as a begrudging acceptance of its practical necessity.
     
  8. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 99, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Good idea to make a model to try things out. This gives more info in less time than any other approach. I think we lost a lot of civilization when the fanatics burned that library. You're right about the Romans and ships, strictly utility and only when necessary.
    It still seems it's just a squaresail with half the area.
     
  9. gilberj
    Joined: Oct 2010
    Posts: 72
    Likes: 4, Points: 8, Legacy Rep: 57
    Location: 034

    gilberj Junior Member

    Here is another perspective;
    About a dozen years ago I was on the East coast of India, near Paradip. The local inshore fishing vessels were essentially sailing rafts, 25 to 35 odd feet long (some more and some less) and 5 to 6 feet wide. The bottom consisted of several thick wooden planks, 4 or more inches thick, tapering towards a finer, but not really pointy bow, and low flared side planks giving a freeboard of perhaps a foot and a half. Dagger boards provided lateral resistance just pushed through slots between the bottom planks. These were wet boats but the water was of course warm. The crew of 4 -6 men and boys generally stood, naked except for a loin cloth.
    The mast was very short, perhaps 6 to 8 feet long and very near the bow. The sail was an acute triangle, with a yard and a boom, sort of a cross between a crab claw and a lateen. When going to windward the sail was strapped in hard, with the yard perhaps 20 to 30 degrees from horizontal. These boats did go to windward very effectively, not of course to challenge a modern keel sloop, but maybe 60 degrees off the wind. The sail in this configuration provided powerful drive and lift, with little healing forces. I don't think they tacked the foot of the yard when short tacking, but on longer tacks they probably did.
    When broad reaching or running before the wind the yard was hoisted to vertical. The boom then spread the sail by weight, with the leach pointing nearly up. In this case the boats did not roll downwind as many do annoyingly.
    I visited the area several times over about two years and got a bunch of really good photo's but sadly these were all lost irretrievably. My descriptions are based on memory and some notes I sent home in letters, and may be slightly flawed, skewed with the passage of time.
    They were/are remarkable boats, clearly efficient and able, venturing 10 or 15 miles offshore in search of fish.
     
  10. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    I actually drew up a ten foot model, using a hull I designed earlier and adjusted its keel design once the rig was drawn.

    The boat is 10ft long, 3ft wide and displaces 504 lbs.

    The sail area ended up being 48 sf.

    The boat scaled up to a 40ft hull length would displace 19 tons and have a sail area of about 768 sf. Not very impressive, but perhaps adequate in her time.

    The yard ended up being about 14 ft, which would scale up to 56 ft on a forty foot hull.

    I found a major size limitation was sheeting angle. As the rig got bigger, the sheet lines had to go further aft. As it is, a 1 ft aft deck extension had to be added to get even half way decent sheeting angle (see attachments).

    The more I think about it, the more worried I get about the enormous strain on the halyard. Perhaps the bow lines could be replaced with yard lifts to even things out a bit.

    When running before the wind, the yard ends up horizontal and the sail acts as a huge kite. Perhaps a third sheet line needs to be added to hold the clew down when in that condition. The two sheet lines, which run all the way back to the end of the aft deck extension, would certainly not do it, unless run through some kind of snatch bloc at the bow.

    It is interesting to see how far the CA moves forward when the boat is running before the wind. As awkward as it looks, it might be quite stable in that point of sail.

    As one end of the yard is hauled down, to sail up wind, the CA moves quite far back. That is why there is a large rudder and an almost ridiculous amount of drag in the keel.

    I find the geometry interesting at least.
     

    Attached Files:

    1 person likes this.
  11. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 99, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    It is interesting and worth making a 3 foot model to try out.
     
  12. science abuse
    Joined: Nov 2009
    Posts: 82
    Likes: 1, Points: 0, Legacy Rep: -3
    Location: Cincinnati, Oh

    science abuse Junior Member

    That is a truly interesting design. You could probably easily mock up a working prototype from an old Snark for a couple hundred dollars, and your displacement would probably be cut in half.
     
  13. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    While I was putting the drawings I recently posted, I found this old drawing I had made when I owned a Super Snark.

    I had sailed it in strong winds with some difficulty, having to feather the flat sail frequently.

    To make the boat more useful in a wider range of conditions, I drew up this sail.

    It has its own boom and yard and, on a windy day, is put on the boat instead of the original rig.

    It is designed to keep the Horizontal Center of Area the same distance from the mast as it was with the original rig.

    It has a little over 45% of the original sail area.
     

    Attached Files:

  14. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member


  15. sharpii2
    Joined: May 2004
    Posts: 2,078
    Likes: 221, Points: 63, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Interesting idea, but a new mast step would have to be devised. The one in the Super Snark(r) is way too far forward. The unknown designer was careful to keep the mast out of the cockpit and achieved that without needing a tall mast or a boom vang.

    That would be difficult.

    Also, it wouldn't be in keeping with my historical argument. The Super Snark(r) is way too light to be a stand in for a scaled down ancient ship.

    BTW-the boat I drew would displace 16 tons, if scaled up to 40 ft, not the 19 tons I posted. Also the yard would be a little over 14ft long on the 10ft boat, not 15ft.

    The S/D of around 12.0 stays. It is a very low number, but I know of several sail boats that have done ocean voyages with S/D's lower than even that. And the S/D of 12 is with the boat loaded to capacity.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.