Square Rig pointing - questions

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

  1. percyff
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    percyff percyff

    I have often wondered about the pointing ability of square rig vessels.

    MIR, the russian sail-training fully-rigged ship can sail easily at 45 degrees to the wind, and can with a good helmsman work up to 37 degrees. See http://home.t-online.de/home/klaus.beuse/baerbel/homepage.htm?/home/klaus.beuse/baerbel/eng_story4.htm for references. MIR wins races under handicap often, and especially when windward work is included.

    Pelican of London, being built in the UK, is shown at http://www.adventureundersail.com/
    and the work to base it on is at http://www.weatherlysquareriggers.com/

    All these are comparable with bermudan rigs at 45 degrees or better. Etchells are regularly sailed at about 30-35 degrees.

    Belem (ex Fantome) a French sail training barque is said to not get much above 80 degrees, and the STA brigs eg Prince William is said not to either.

    The major obstacle is that of the bracing angle that the yards can obtain to the centreline, and this can be improved in most designs.

    Either some of the above is ficticious, or there are a lot of square rig vessels that are not being sailed well, or need attention.

    Any comments?


    percy westwood
     
  2. mrn
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    mrn New Member

    dynarig

    At the moment there has been loads of research on squarerigs with as result the dynarig. This is a modern square rigging. The Maltese Falcon designed by Gerard Dijkstra will be the first vessel with a dynarig. I have been to a symposium where they gave a presentation about the dynarig. And I was kind a suprised and I really believe that dynarig will be the next page in the live of square rigging because the upwind performance will increase huge.
    www.gdnp.nl
     
  3. FAST FRED
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    FAST FRED Senior Member

    Nelson's logs show 90 deg tacks for a fleet of very indifferent vessels.

    Sea state makes the difference in offshore pointing , as it takes POWER to climb 10 to 20 ft hills, and at about 45deg there is enough power to keep going.

    What a day sailor can do pinching in flat water has little to do with a real boat in the briny blue.

    Most of the "advances" in square rigs have been in reducing crew size and training levels. Tie Gaskets aloft anyone?

    FAST FRED
     
  4. brian eiland
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    brian eiland Senior Member

    Maltese Falcon and square rigs

    Some interesting sites you posted there. I will have to read them when I have a bit more time.

    The Oct issue of Yachting World had a pretty nice coverage on the new 'Dynarig' Maltese Falcon.

    Quoting the article, "One reason square-rigged ships could not sail close to the wind was the positiion of mast shrouds, which prevented yards and sails being angled to use the wind efficiently" In other words they could not get the leading edge of the square sail around to a proper angle of attack to the wind. The free standing mast of Maltese Falcon will allow this. Otherwise one would have to 'release' the leeward shrouds on a conventional square rigger....I don't see this happening.

    You might also note their determination that the arc in each yard has been determined as 'critical' at 12 degrees.

    On another thread, Sail Aerodynamics, I posted this observation,

    "DynaRig slot effect:

    Here is another affirmation of the slot effect....look at this new DynaRig proposed for the 285' Maltese Falcon:
    <http://www.doylesails.com/newsletter-03-pg8.htm>

    Note the sheeting angles for the three sails, and particularly that of the very forward sail. Now why is this?....look at the explantions of the slot effect.

    And which sail do you think is providing the greatest drive forward, and which sail is providing the greatest leeway??

    Interestingly, they are not trying to account for the wind gradient (twist) with this new design even though it is an extremely tall rig
     

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  5. percyff
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    percyff percyff

    Square Rig Pointing

    Thanx for all the responses -

    I suppose I am confused that some square rig vessels can point (I regard less than 45 degrees as going to windward like a dazed crab) and some can't. What I surmise is that the some that don't have yet to have a capable sailing technician on board, and many just *think* its impossible. My attempt through these forums (fora) if anything, is to ask those who can point, how they do it; while those who can't, why?

    The bracing angle (for a traditional 1880-1920 steel yard, wire shrouds rig) is a function of:
    Clearing under the stay above
    Fouling against the forward shroud
    Mast crane extension forward of the mast

    But this can be worked to 30 degrees - as on MIR.

    Alternatively - as in the description of the tacking of MIR - is it a technique issue, waiting for the vessel to accelerate after tacking and then delicately fining up on the wind, with very careful steering, at the same time as trimming the stacks (Colin Mudie reckons) 5 degrees freer each stack - MID has 7 stacks - headsails, foremast square, main staysails, main square, mizzen staysails, mizzen square, spanker. Colin Mudie gives a description of a dinghy sailor sailing Lord Nelson, barque, on the wind by using the spanker as a mainsail and the foresails as a jib and sailing it like a dinghy, with everything in between hauled tight. It doesn't work!


    Is there access to Nelson's logs online?

    Are there any crew on square riggers who can update this sketchy information?

    Is there a site somewhere that gives this type of information?

    Can riggers advise what bracing angles they are getting on modern vessels?
     
  6. D'ARTOIS
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    D'ARTOIS Senior Member

    The clearing of the "Thermopylae" caters for just 60 degrees; The foremast allows for a few degrees more.
     
  7. Skippy
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    Skippy Senior Member

    I don't see any slot effect on that page. All I see is less of a low-pressure region (less green/blue) on the leeward side of the aft sail, and less of a high-pressure region (less less orange/red) on the windward side of the forward sail. If those are less than what you would get with just one sail, which I suspect is the case, then it's just interference among the sails. There's also the less advantageous wind angle at the middle and especially the leeward sail, due to the backwash of the middle and especially the forward sail.

    I also don't see any discussion of the slot effect on that page.
     
  8. percyff
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    percyff percyff

    D'artois - how you measuring the angle?

    D'artois - how you measuring the angle?
     
  9. D'ARTOIS
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    D'ARTOIS Senior Member

    I have a large replica of "Thermopylae" - later on she was re-rigged and renamed when she was sold to the Portugese under the name "Pedro Nunez".

    From that model I can measure the free movement of the spars; in that model the rigging is minitiously copied ( scale 1: 70 )
     
  10. percyff
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    percyff percyff

    D'artois
    Sorry for not posing the question well - do you mean the yard on Thermopylae can swing from athwartship through 60 degrees (in either direction), so the yard ends up 30 degrees from the centreline? - If so that is the same as Mir. Mir is notable that (when well handled) she can carry only 7 degrees of angle of attack of wind on the yard angle. The thermopylae would have the same potential even if with less stable sailcloth.

    I am researching the two ships built by J White of East Cowes, Isle of Wight: the Waterwitch of 1832, and the Daring of 1844. Waterwitch was built for Lord Bedford, and was said to sail rings round the best the navy had, in fact the vessel laid in wait at Portsmouth to demonstrate. Lord Bedford wanted reform of designs for the navy. Waterwitch was taken into the navy later and performed well in chasing slavers. Daring was said to be even better - as regards weatherliness - they were 330 ton and 460 ton respectively and both brigs. The navy had experimental squadrons to pit boat against boat in 1844, 1845, and 1846, and these two brigs were included. Unfortunately the rise of steam at the same time took the need away from the experiment. Records show bracing angles (angle between the yard and the centreline when hard on the wind) as low as 19 degrees (plus 7 = pointing at 26 ?).

    Thanks again for all contributions.
     
  11. DanishBagger
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    DanishBagger Never Again

  12. gggGuest
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    gggGuest ...

    Its an interesting thought that if you joined up all the gaps ina typical square rig boat so that the sails operated as one continuous sail the profile you would be left with would be very similar to a classic square tip tapered plan aeroplane wing (P51 for instance), and potentially rather more efficient than a triangular bermudan sail. You've also potentially got better twist control. On the other hand there's loads of extra rigging and all the posted problems of sheeting angle...
     
  13. brian eiland
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    brian eiland Senior Member

    Square Rig hard on the wind

    In posting #4 above I had made reference to a Doyle Sails site that is no longer a good link. Sea Spark has recently posted a new reference site on another thread:
     
  14. Cliff Pope
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    Cliff Pope Junior Member

    I think there are two ways of close-hauling a square rig. The one so far discussed is limited by how far the yard will swing round, but presumably keeping it basically horizontal.
    I read of an experiment with a replica Viking longboat some years ago, and it was found that by canting the yard as well as swinging it round, the yard itself became the leading edge. In effect it turned into a lug sail. Obviously that method is only applicable to a single yard with very basic mast staying.
     

  15. brian eiland
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    brian eiland Senior Member

    Pointing Capabilities of Sq Rig

    Did you ever come up with more data on this pointing capability??
     
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