Tacking vs. wearing square-riggers — relative time and distance

Home Forums Nautical Research: 1500 – 1830 Tacking vs. wearing square-riggers — relative time and distance

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  • #10494
    Gina Willis
    Participant

    To answer this question, I’ve studied Harland’s Seamanship in the Age of Sail, as well as Sam Willis’ tomes and other good sources, to no avail:

    Situation: A squadron of 5 Napoleonic-era Royal Navy square rigged corvettes, in line-ahead formation. They are beating to windward (heading S, with wind from the SW).
    The commodore wants to change the squadron’s heading to W.

    The squadron could tack in succession clockwise through S and SW to achieve the W heading.
    Or it could fall off the wind and wear in succession all the way around, anticlockwise, to achieve the W heading.

    I realize that many different and very specific factors would have determined which option the squadron would take — whether the squadron had sufficient speed to tack at all, the handling characteristics of each ship, the crews’ quality and training level, proximity to an enemy force, etc. But, all other things being equal…

    Question 1: How many minutes would it have typically taken this sized squadron to complete the tack, compared to the wear? I’ve read that a well-trained RN crew of the period could tack a ship in about 5 minutes. Considering that 5 ships would have to tack in succession, that would be at least 5 x 5 = 25 minutes for the fill squadron to complete the change of heading by tacking. How long would it have taken this same squadron to wear instead?

    Question 2: The sources I’ve read usually say tacking took more time to complete the heading change, but lost much less ground to windward. Wearing accomplished the heading change faster, but would make very little progress to windward. Let’s say our squadron is plotted on a map with a 1 km square grid. In the space of one hour, all things being equal, how far along its new W heading would it have gone after tacking compared with its progress to the W after wearing?

    #10512
    Frank Scott
    Participant

    In addition to the books that you quote I would commend Patrice Decencière, ‘Three French sailing ship performance trials’, Mariner’s Mirror 94:3 (2008), 276-84, as well as two excellent articles by Sam Willis in The Northern Mariner, both available (free) on-line on the Canadian Nautical Research Society website:
    http://www.cnrs-scrn.org/northern_mariner/vol13/tnm_13_4_29-39.pdf
    http://www.cnrs-scrn.org/northern_mariner/vol14/tnm_14_3_57-68.pdf

    The first point is that a formation of ships in line ahead could tack in succession, while preserving their order, but risked problems if any vessel failed to tack (‘missed stays’). Although wearing was generally more reliable (see first article by Willis for a notable exception), if you tried to wear in succession that would mean that the leading vessels that wore would have to pass through the line of vessels on the original tack, which was clearly risky. If you wore, you wore ‘out of line’, as Nelson did at the Battle of Cape St Vincent, though even then he had to pass between HM Ships Diadem and Excellent to complete his manoeuvre.

    In tacking you only have to turn through about 12 points, to wear you have 20 points to cover, which will obviously take longer. Not sure where you have read that tacking was slower. In light airs it is possible to ‘wear short’, by backing the foremast at the start of the manoeuvre, but this would not make it any more suitable for a formation. If you wanted to make any ground to windward, tacking was the only option. It was bad enough to wear a single vessel, but a whole formation would lose inevitably a huge amount of ground.

    Another issue is that this was all much easier in a frigate (the Royal Navy of that era did not have corvettes), than it was in a ship of the line. Even frigates became less handy as Great War with France progressed, and navies competed to build bigger and bigger ones. With greater size came heavier guns, but the price was a reduction in manoeuvrability or handiness.

    Final point is that when tacking in succession each ship that was tacking would stop quite quickly at the start of the tack, and enough space had to be allowed between the ships to ensure that the ship astern had not caught up before the tacking ship had gathered way & made space. Thus for a line of ships changing tack you had to allow the time for each tack, plus what might be termed a ‘fudge factor’ to avoid collisions.

    None of the vessels would handle exactly the same, and the wind and sea conditions would never be exactly the same for each tack, so lots of imponderables. All difficult enough with coppered ships, what it must have been like with un-coppered squadron (some long out of dock), I dread to think.

    Frank Scott

    #10541
    Malcolm Lewis
    Participant

    I recall reading that in the Georgian navy their Lordships forbade warships to tack unless “in the chase” for fear of costly damage to rigging and canvas which was often difficult to repair especially when some distance from port. Captains were instructed to “wear ship” instead.
    Before Trafalgar the combined French and Spanish fleets were heading for the Straits of Gibraltar when the French Admiral Villeneuve changed his mind and ordered his fleets to return to Cadiz. To reverse the course of forty one square rigged ships of various sizes with different hull conditions, combined with the lack of experience of many of their crews, must have presented a problem. They would have been in some disarray by the time they were eventually engaged by Nelson’s fleet.
    Several of Nelson’s ships also struggled to get into the fray in the light airs much to the frustration of their Commander in Chief.
    Fifty five years later the mighty HMS Warrior proved a handful to manoeuvre and apparently could take up to 50 minutes to tack even in a strong breeze.
    Malcolm Lewis

    #10544
    Gina Willis
    Participant

    Thank you, gentlemen. But I think in order to better state my question and get the answer I need, I should show you a picture of the situation and tell you why I ask:
    This is for a simulation of the 1813 campaign on Lake Ontario:
    Hypothetical tack vs. wear situation
    Here is the situation: The wind is from the west. The British force containing 5 ships (2 corvettes, 1 brig, 2 schooners), heading NW, is maneuvering against an American force off its port bow.
    The British force wants to make a turn to a S heading.
    My sources say these crews could tack a ship in 5 minutes. So to tack in succession, I’d say it would take 5 ships x 5 minutes = 25 minutes to complete the tack.
    The time and distance scale here is 1 km = 1 speed point = 5 minutes.
    Since this force has a current speed of only 3, it doesn’t have sufficient speed to tack.
    But let’s say it had a speed of 5. Then, according to my rule, it would be rotated in place to a S heading and it speed would be reduced by 5 points to 0 (1 point per ship making the tack). That would complete its movement for the turn.
    My question is, what should happen if the British force were to wear ship to achieve a S heading?
    How long should it take to complete the heading change? Or, to put it another way, what should the equivalent cost in speed points (1 point = 5 minutes) be in order to wear instead of tack?
    And, once the heading change is complete, what square should the British force be in? Should it be displaced one or more km to leeward, for example? Or would a force this size have been able to complete a wear within a square kilometer area?
    Also: If I understand your comments correctly, you’re saying that it would have been impossible for a force in line of battle to “wear in succession.” They could wear, but once they completed the heading change they would no longer be in line-ahead formation.
    Thank you in advance for your help and suggestions!

    #10545
    Frank Scott
    Participant

    Your scenario now makes sense, if I understand your diagram correctly. It has the wind from the East (though you state west), so the ships in the squadron are well off the wind, rather than close-hauled, and are making only a moderate course alteration. So they could wear in succession, just as a parade ground formation does a ‘wheel’. The wind will merely move from the starboard quarter to the post beam. No problem at all, just a case of ‘follow my leader’, and no loss of speed.

    Other points:
    There should be no problem tacking such small vessels at 3 knots in what I take to be smooth water. Could be a problem if there was a lumpy sea left after bad weather, more sea than wind is never good for performance.
    A point is 11.25 degrees, so 32 = 360 degrees.
    The problem with wearing in succession when going from close-hauled on one tack, to close-hauled on the other, is that the lead ships have to pass through the line of vessels that are still on the original heading, so there is an obvious risk of collision.

    #10547
    Gina Willis
    Participant

    Actually, the wind is from the west. In my diagram the wind arrow is like a weather vane, so it points to the direction the wind is

      from

    The British squadron in the diagram is heading NW, so it is close-hauled on the port tack.
    At the end of a wear maneuver, it would be heading S, on a beam reach on the starboard tack.
    Would your point about being able to wear in succession and have no loss of speed still hold true?
    How long would the wear take, and would it occur within one square, or require any displacement to leeward?

    #10569
    Frank Scott
    Participant

    As this is for a Board Game, rather than a Computer Simulation, suggest that a wear takes same time as a tack, but displaces one square to leeward.

    Frank

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