Square Rig pointing - questions

Discussion in 'Sailboats' started by percyff, Dec 22, 2004.

  1. percyff
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    percyff percyff

    I have nothing further.

    The Pelican website http://www.adventureundersail.com shows the maiden voyage postponed from October 2006, and suggests sailing trials in November 2006, but until the results of those are known we will not have any useful full-scale data.
     
  2. brian eiland
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    brian eiland Senior Member

    Square Rig Pointing

    I know some discussions on this subject came up over on another subject thread, and included this site reference. Just thought it should be added here.

    http://www.weatherlysquareriggers.com/
     
  3. brian eiland
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    brian eiland Senior Member

    Improving the Sailing Qualities of Square Rigged Ships

    Appears as though this link to 'weatherlysquareriggers' is no longer available.

    I'm wondereing if this paper is still available online?
    Brigs And Polacres with Windward Ability
    (Improving the Sailing Qualities of Square Rigged Ships)​
     
  4. brian eiland
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    brian eiland Senior Member

  5. ancient kayaker
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    ancient kayaker aka Terry Haines

    Just discovered this thread. Wish I had seen it earlier. Here are my thoughts on the weatherliness of square rigged boats and ships, some of which have already been aired by others:

    Limitations imposed by standing rigging has been discussed: obviously if the yards cannot be rotated enough to bring the sails to bear on the wind then that’s that. In ancient times there were also limitations imposed by material especially sailcloth which probably did not permit much improvement and of course most sailors held strong convictions about the efficacy of full cut sails. It should not be forgotten that old-time square riggers also had fore-and-aft sails; although the clippers and windjammers carried significantly less fore-and-aft sails than ships of Nelson’s day, I suspect that was largely due to the markets they served and the trade winds.

    There were also limitations imposed by hull design: old-time square riggers were all of a piece, sail improvements and hull improvements tend to go together. The full-length keel was a consequence of building methods and the fin keel was far in the future, requiring new hydrodynamic theories before it could even be contemplated.

    Each of the above points represents a potential area for improvement in square rigged performance. The Maltese Falcon demonstrates most of these, with no standing rigging except on the radar mast, sails of advanced materials, and no fore-and-aft sails at all. The Maltese Falcon does not show updates in all areas however, in particular the hull design. Of course one can question the practicality of a fin keel on a vessel of this size; imagine the draft or the effect of a retractable foil on the accommodations. And yet, in these days of high fuel costs and concern over impact on planetary ecology, who knows -this vessel might show the way for future commercial shipping.

    It seems to me that the sail design of the Maltese Falcon approaches a wing sail, also see http://www.boatdesign.net/forums/sailboats/square-rig-variation-30031.html - I would like to try it on a small sailboat; I suspect pointing could be improved. The big problem that I can see is the backwinding of the sails during tacking. Was this problem ever solved for square riggers, other than by wearing ship? This is more of a problem for a small, lightweight boat, lacking the momentum to shoulder through the turn.
     
  6. brian eiland
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    brian eiland Senior Member

  7. brian eiland
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    brian eiland Senior Member

    This discussion had fallen into the 'older' category and I had to initiate its return to current capabilities.

    You are correct, these issues require resolution in particular aboard a multihull lacking the inertia of a ballasted keel to carry it thru the tack.
     
  8. ancient kayaker
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    ancient kayaker aka Terry Haines

  9. brian eiland
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    brian eiland Senior Member

  10. brian eiland
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    brian eiland Senior Member

     
  11. gonzo
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    gonzo Senior Member

    Sails only partially impact the ability of a ship to point high. The hull and rig also have to be considered. A modern hull with a deep keel and square sails will point higher and sail faster than a galleon with modern sails.
     
    Last edited: Nov 3, 2023
  12. CarlosK2
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    CarlosK2 Senior Member

    (...)

    Pointing/Beating Angle =

    = HydroDynamic Drag Angle + AeroDynamic Drag Angle
     
    Last edited: Nov 5, 2023
  13. CarlosK2
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    CarlosK2 Senior Member

    (...)
     
    Last edited: Nov 5, 2023
  14. brian eiland
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    brian eiland Senior Member

    It is NOT a square rigged vessel, so why post it in this discussion?

    It may be obvious that they were not accomplished sailors if they were not able to get that sloop out of harms way. Then again they may have allowed themselves to get too close to the surf line.
     

  15. sharpii2
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    sharpii2 Senior Member

    I find this to be an interesting discussion.

    But I think there are a few myths here.

    One is that it is difficult if not impossible to bring a square rigger about. Not true. Actually it is quite easy in all but scary conditions. Typically, the fore most square sails are set aback. What happens then is that the wind actually pushes the bow over to the other tack. I had to use a similar technique to get my lightly loaded Siren 17 to come about. I had to back the jib instead. But that had exactly the same effect. Once I mastered this technique, I was able to change tacks smartly, even in strong winds.

    Two is that the windward ability of a square rigger is limited only by interference with the shrouds. This is somewhat true. But an even bigger limitation is the brace-line angle. As the yard arm moves closer to the centerline, the angle of the brace line gets more and more acute. This and its very long length reduces its holding power considerably. One solution to this is to have double brace lines. One goes far aft as usual. the other goes to nearly amidship. This widens the forward bracing angle considerably, but is only useful when the yard arm is swung hard forward. That is why the original stern one is still required.

    A further improvement is to have a forward tack line, which holds the lower forward corner of the sail tightly forward. This does not replace the sheet line, which is used when sailing down wind. So now there are eight control lines for the sail, not including yard-squaring lifts or the halyard (four on each side). It is also posible to mount the yard on a srut that projects in front of the mast to avoid the problem of the shrouds being in the way. But this adds weight and complexity. I conceived all of these suggestions when considering the desigh of a 12 ft dinghy that is rigged as a cog (only one square sail and no jib or other fore-and-aft sail).

    Its single yard had no yard-squaring lifts and was held to the mast with only a pendant. The mast was to be held up with a forestay and a single pair of back shrouds. But the sail was to have the eight control lines mentioned above.

    The underbody of the hull was just a long, shallow keel, which had a good sized curwater and skeg. It also had a catboat style, long, shallow rudder (which a real cog did not have).

    I can imagine that sailing it to weather would be PIA. One would have to be quick and know exactly what he is doing to pull it off. A short, deep keel or dagger board would definitely improve its windward prospects, but would enable it to turn too quickly, so one would be way off course before he got the tack line and the forward yard brace line settled in. I doubt that it could do much better than a glorified close reach.

    It seems that after steam powered tug boats appeared. the design and proportions of square sails changed a lot. They became much more low aspect. Clearly, this was to improve downwind behavior, as the low aspect ratio sail provided a very real upward lift component and far less turbulance in front sail when sailing down wind. They also seemed to have lost all their between-mast staysails, keeping only their jibs, and a spanker sail on the aft mast. Clearly, they were dedicated downwind sailing machines.

    Here is a profile sketch of my proposed cog 12 ft dinghy. The amidship brace lines are not shown.


    SqSaF3.png

    I like the dynaship concept a lot. But I think its inherent high cost pretty much religates it to billionaire's yachts. I doubt that I will ever see a working ship with such a rig. I think cargo ships of the future will be huge, as they are today. They will likely be powered by nuclear reactors. Smaller vessel, for more local traffic, in sparsely populated areas, will have to be smaller, and will likely have sails. But they will most likely be fore-and-aft, schooner rigged.
     
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