Maneuverability of Square-Rigged Vessels ?

[Didz]

Please forgive my intrusion on your forum, but I have a sail related question which I hope the experts on this forum will be able to answer.

I am interested in 18th and 19th Century naval history and a question has arisen about the relative manoeuvrability of modern day propeller driven ships and the various designs of square rigged warships used in the past.

It’s relatively easy to find a clear assessment of the factors that affect the manoeuvrability of prop driven vessels, and I have not had difficulty finding a formula for the calculation of things like turning circle radius based on hull length, weight, speed etc for modern day vessels.

However, I did do some sailing in my youth and my instinct is that the factors affecting the manoeuvrability of a sailing vessel are not the same as those affecting a prop-driven vessel.



For one thing sailing vessels are not pushed through the water, but pulled along, and like a horse and cart, I would have thought that turning has as much to do with the redirection of effort as pressure on the rudder.

So, the question is ‘What determines the manoeuvrability of a square-rigged sailing ship, and how would it differ from a prop-driven vessel?

Secondary, questions relate to the relative performance of a 3rd Rate Ship of the Line, to say a 5th or 6th Rate Frigate, and the importance of speed in the preparation to tack, rather than wear ship.

I am interested in any input from skippers or crew who have experience of sailing square rigged vessels, or links to any sites where this subject is discussed in more detail.

[Dockhead]

There are enough square rigged ships still around that you will probably find someone who has actual experience on one. I have no such experience, but can give you a couple basic comments.

"For one thing sailing vessels are not pushed through the water, but pulled along, and like a horse and cart, I would have thought that turning has as much to do with the redirection of effort as pressure on the rudder."

You can steer a sailing vessel somewhat with sail balance. But the rudder is the main means of steering. Pushing or pulling has nothing to do with it.

"the importance of speed in the preparation to tack, rather than wear ship."

Tacking is very difficult in a square-rigged ship, because a square-rigged ship cannot sail as close to the wind as can a fore-and-aft rigged vessel like a modern sailboat. You have a bigger angle to get through and a greater risk of "missing stays" and getting stuck -- "in irons". Obviously you need momentum -- speed -- to get through the large angle during which your sails are not giving you any drive. The faster you are going, the easier it is to do. It's the same with modern sailboats, only easier because the angle you have to get through before you start getting drive on the other tack is smaller.

On the contrary, square rigged ships were a doddle to jibe, so changing tacks was often done by "wearing ship" -- heading off, coming all the way around through a jibe, then heading up on the other tack. On our boats, it's the jibe which is harder to do than a tack, so we have the opposite maneuver from what the square-riggers used to do -- a "chicken jibe", where in order to avoid a tricky jibe, we head up, come all the away around through a tack, then head down on the other tack.

There are tons of information about this in literature. Try, for example, Coggins, Ships and Seaman of the American Revolution, 1969 -- a great read in any case.

[Didz]

Originally Posted by Dockhead

There are enough square rigged ships still around that you will probably find someone who has actual experience on one.

Thats what I figured, which is the logic behind my decision to post a question here. It seemed a bit silly to be discussing this issue on a history forum and scouring through hisotrical texts for answers when similar ships are still being sailed today and there are people who have actually experienced the way they behave.

Originally Posted by Dockhead

You can steer a sailing vessel somewhat with sail balance. But the rudder is the main means of steering. Pushing or pulling has nothing to do with it.

I can understand that but your later comments do suggest that square rigged ships had the ability to change course in a shorter distance than a power driven vessel.

I'll certainly have a look for the book you mentioned.

Thanks

[MikeTurner]

"I can understand that but your later comments do suggest that square rigged ships had the ability to change course in a shorter distance than a power driven vessel."

I also don't have any experience in sailing square-rigged vessels. Yet. But I own and sail a two-masted, fore-and-aft rigged schooner, which historically is a rig somewhat in between square-rigged and today's modern sailplans. Schooners can sail closer to the wind than can a square-rigged ship, but not so close as a modern sloop or cutter.

On your point I've quoted above, in some instances I'd suspect a sailing vessel could change course in a shorter distance than a power driven vessel - but perhaps not as quickly. Assume for instance that a vessel wants to exectue a 90 degree turn. The power driven vessel will continue at a constant speed and execute a turn that will be based on its turning radius. The direction of the wind will is immaterial.

A sailing vessel, by contrast, will have to take the direction of the wind into account, and the wind direction will alter the speed of the vessel through the turn. When sailing with the wind, a sailboat can only travel as fast as the wind. As the boat turns, first across the wind and then closer into it, speed may actually increase. This has to do with the physics of how a sailboat actually sails: downwind, it's primarily a factor of the wind; on other points of sail, it's a combination of the wind and the forces of the water on the hull (kind of like squeezing a pumpkin seed between two fingers - the pressure of wind on one side and water on the other forces the boat forward).

As a sailboat then tacks through the wind, speed decreases as the boat points into the wind and then increases again as the boat comes over onto the other tack.

So it's possible that in some instances, comparing a power- and sailboat of the same length, the sailboat could turn inside the turning radius of the powerboat. The powerboat will execute a turn at a constant speed based on its turning radius. The sailboat, when tacking (and to a lesser extent when gybing) will tend to slow and pivot around it's keel in making the turn, rather than executing the radial turn of the powerboat.

I may not be explaining this terribly well and the above is based on my experience vs. any engineering-type analysis (I have neither been an engineer nor played one on TV). The distance covered by the sailboat might be less than the powerboat - but the powerboat will execute its turn at a higher rate of speed.

This analysis, incidently, doesn't take into account powerboats with things like bow thrusters and the like - but those are typically used at low speed, such as when docking; not in high-speed actions such as those you'd encounter in a running naval engagement.

[Blue Stocking]

Spent some time aboard Charles W Morgan at Mystic Seaport. Always thought that small area of rudder would have very little contribution to any reasonably quick changes in course, say, 30 ship lengths.
The helm assembly is mounted on the forward end of an approx 12ft tiller, with simple 2 to 1 ratio purchase out to beams.
Doesn't look to have much mechanical advantage, to induce precision steering.

[MarkJ]

Its interesting that the historical novels don't help much! Alexander Kent and Patrick O'Brien I would have thought would describe the actual sailing more factually.

I just finished an Kent novel and his description of Antigua and English Harbour showed he had never been there, or was drunk for the duration. Action sequences totally confused me to wonder if wearing had been confused with tacking or visa versa.

I sailed on a tall ship for 2 weeks about 20 years ago but similar to the historical novels the captain didn't think the paying crew were worthy to be educated! Plus he just bunged the engine on.

Lastly, only 2 ships trying to board each other or get within firing range would put their vessels to the limits, so maybe we could hire 2 Ships of the Line and time the maneuvers?


Mark

[nigel1]

See if you can conatct anyone at this organisation, they may be able to help, or point you in the right direction

Sail Training International - Class A Tall Ships Forum

[nv5l]

You've probably already read these, but I remember Dana's "Two Years Before the Mast" had some descriptions of maneuverability, with one rather humorous one in particular.

But he also published a very good book on seamanship, where he described ships and their rigging in great detail. I've only read parts of that one so far, but found it to be very good.

[Dick Pluta]

I'm pulling this up out of memory (mine, not the computers) but there is a fairly long practical discussion of this in Sterling Haydens book "Wanderer". For those too young to know, he was a John Wayne type who was "discovered", had a movie career he hated, dumped the movie actor life and ran away to sea (or maybe back to sea). In the process he bought and sailed, among others, a square rigged ship and sailed her in trade. He learned how to sail her the hard way and wrote about it in some detail,as I recall. If my memory is faulty and the discussion isn't as lengthy as I recall, the books a great read anyway.

Dick Pluta
AEGEA

[Dick Pluta]

Originally Posted by nv5l

You've probably already read these, but I remember Dana's "Two Years Before the Mast" had some descriptions of maneuverability, with one rather humorous one in particular.

But he also published a very good book on seamanship, where he described ships and their rigging in great detail. I've only read parts of that one so far, but found it to be very good.

This is funny. I just this morning finished re-reading this. The humorous incident in question is really funny and not one you expect to see from a "professional" captain. I've some of my friends in like situations but never a "pro".

Dick Pluta
AEGEA

[rgscpat]

Didz, are you in a part of the world where you can visit a nautical museum? You could then easily strike up conversations with volunteers who could give you all sorts of info.

As I've gleaned from all the old sea stories and talking to people:

Some other differences in maneuverability had to do with the size and skill of the crew. The warships of the age of "fighting sail" had large crews, though these varied in skill. It was uneconomic for merchantmen to have large crews and even more so in the clipper ship era, where ships needed to be set up for small crews to handle large vessels.

The push-pull is sort of relevant to the basic ideas of points of sail; sailboats traveling to windward rely mostly on lift generated by sails, which a square rig can't do as effectively as fore and afters. Also, the way the old ships were set up, tacking was considered risky both from a perspective of the danger of being caught in irons as well as possible damage to the rig. Big ships of the line had lots of momentum -- but needed a lot of wind to get that momentum, given that they could easily displace two or three thousand tons. Also, in battle, the ships generally fought under "plain sail" and tended to not use their lower sails (courses) because of fear of igniting the canvas. And, as part of maneuvering in battle, ships would try to protect their vulnerable sterns -- or rake the vulnerable stern of an enemy. And, in the Napoleonic era, British ships were sometimes on blockade duty for long periods without opportunity for refit, leaving their bottoms foul with marine growth and hence slower than a freshly cleaned and coppered hull.

[HappySeagull]

here's a start:
Ocean Navigator | The magazine for long-distance offshore sailing and power voyaging.
There are hints that they were a lot more "maneuverable" (with the right crew) than one might think,though,'twould all seem to be in slow motion to modern folk.

..and I never saw a stupider movie than "Master and Commander" or whatever it was.Hornblower is the one and only,unless you get into the non-fiction.

[Didz]

One dissapointment I had quite early on was 'YouTube'. I thought that I would easily find some real life footage of square rigged ships changing course and be able to see for myself how nimble, or otherwise they were and at least get a feeling for whether they could change course in a shorter distance than a power vessel.

But frustratingly after watching numerous beautiful ships in full sail not one of them altered course for the entire duration of the video's. It seems that squarred rigged ships look better when under full sail on a straight course, and so thats how they get filmed.

@Happy Seagull: Thanks for the link. I picked up a couple of facts from that article which seem to be key to the process.

Namely:

In winds of less than 10 knots, a large sailing ship may not have enough momentum to complete the exercise and can end up "in irons"or stopped dead in the water. At the other end of the scale, in strong winds the foremast carries a vast frontal load when the sails are aback. Because the masts are braced from behind, that enormous pressure has the potential to snap a mast. In strong winds and heavy seas, therefore, when tacking could be dangerous.

That scenario also suggests that in action a square rigged ship carrying reduced sail and with chained yards to reduce rigging damage would also find it difficult if not impossible to obtain the momentum to 'Tack' reliably.

I also found this explanation of box-hauling interesting, in so far as it suggests that the method allowed a square rigged ship to change course virtually on the spot without gaining or losing distance. Though again it sound like an maneouvre that would put a lot of strain on the masts and would need a minimum wind strength to achieve.

Box-hauling, although rarely used, combines the tack and wear to change from a zig to a zag in a restricted space. The ship is turned into the wind until the square sails backfill. Before the bow can swing through the wind, the yards are pivoted so the ship turns quickly back to its original heading; then around to a point where a wear will complete the exercise. On the desired new heading and under way, she should be roughly at the point where she began the maneuver.

This statement was equally interestng but frustratingly failed to quantify what was meant by 'a lot of hard won ground' (e.g. turning radius)

In strong winds and heavy seas, therefore, when tacking could be dangerous, a square-rigger is put on the opposite tack by turning her away from the wind through 240°, effectively gybing her. This is known as wearing ship, an easy maneuver that requires plenty of sea room but loses a lot of hard won ground. Wearing ship, in its simplest terms, means sailing a large downwind loop.

[nv5l]

My battery's low -- on the boat -- so I can't really watch them, but have you looked at any of the tall ship race videos?

[MichaelC]

The single most important element in tacking a square rigger was the skill of the captain and mate, and the skill of his highest ranking sailors. Absolute. When you tack a square rigger, you don't just put the helm over and wait for the vessel to pass thru the wind, you back the foresails to catch the wind on the opposite side to drive the bow thru, much like we gaffers back our jibs to push the bow theur the eye of the wind. I had a square sail on my schooner [making her, when square sail was set, a mini brigantine]. I always backed the square when coming about, and she would spin on a dime when I did so. Obviously, with a screw driven vessel, you can turn her with more certainty than a sail driven vessel. In a shorter radius? Well, it depends on the wind, the underwater profile, the depth of forefoot, the skill of the master, and oh, yeah, the consistency of the wind. Look to the technical discussions in the better sea books [the Hornblower series is good for this, the O'Brien not so good]. Look at John's Nautical Pages for sources. Put a square rig on your dinghy and find out how it works. a bit of polytarp and couple of boards, some 1X3 laminated together for the mast and you have an automatic laboratory.... BTW, you can sail a single rigged boat with no rudder at all, just by shifting your weight fore and aft in the boat. Try it. It is fun ....