Historical data

Some quantitative historical sources:

W. Froude, "The Resistance of Ships"

This records drag experiments on a wooden ship, from 1871. The numbers give a drag coefficient of 0.0045. I tried this, but it made things too slow, going by other sources, so I have reduced it. A typical modern figure is around 0.0025.

P. Decenciere, "Three French Sailing Ship Performance Trials", Mariner's Mirror, 2008; and "Some Eighteenth- and Nineteenth-century French Trials of Square-rigged Warships Tacking", Mariner's Mirror, 2011.

"Performance Trials" has some very nice polar diagrams, including one for the Jean Bart, an old-fashioned 80-gun ship tested in the 1870s. At a wind speed of 9m/s it shows around:

8 kts close-hauled
10.5 kts on the beam
9 kts on the quarter
7.5 kts before the wind

This is without studdingsails, but presumably with royals. Studdingsails add about a knot and a half. Speeds with less wind are roughly proportionally lower.

"Warships Tacking" is gold dust, and includes timings of the different steps in the tacking procedure, and in some cases even speeds throughout so that you can chart the ship's track. Typical timings are, for a 64-gun ship starting close-hauled at 5kts,

0s- start the turn with the helm (?)
55s - foresails aback
2m - wind right ahead
3m - ship dead in the water
4m 15s - making way
4m 45s - close hauled on the new tack
(with big variations on the later steps).

A.M. Glebov, "The Analysis of Propulsive Quality, Stability and Controllability of the Ships of the Black Sea Fleet During the Russian-Turkish War of 1828–1829 Basing on Contemporary Data" (in Russian) 2012

See MartesZ's post here: https://itch.io/post/1044880 . In particular, this has at wind rate 5, i.e. 8-10m/s,

- Close-hauled 7 kt
- Beam reach 9.5 kt
- Broad reach 11 kt
- Running 8 kt
Heel angle
- Wind rate 5 - 11 deg

R. Braithwaite, "Notes to accompany drawings of the 32 gun frigate HMS Southampton", "HMS Southampton Stability Analysis", "HMS Southampton Velocity Prediction", 2009 

These are notes by a naval architect and model builder, applying some modern engineering analysis to a 1757 frigate, with some comparisons to historical reports on the ship. If I'm reading the stability analysis properly, you don't want to heel it more than 45 degrees or it will fall over.

Some questions: what exactly does close-hauled mean? How much leeway are these ships making? Are some ships typically faster with the wind on the beam, others with it on the quarter? (The French study has examples of both.)

I am working on tuning the sailing model towards these numbers. In my current development build I get, with wind 9m/s, the starting situation at "the world":

Close-hauled - 6.5kts  (wind one-and-a-half points before the beam)
Beam - 11kts
Quarter - 10kts
Before the wind - 7kts.

Probably the speed before the wind is about right (since I do not have royals) and the others should be a little slower.

Get A Painted Ocean


Log in with itch.io to leave a comment.

(1 edit)

First of all, here is my information trove. The Lively-class frigate is about halfway down.

You will probably be most interested by Gustav Adolph Wasa.jpg


To take a crack at your questions:

When sources write 'close hauled' I interpret it at as 'full and by' with the sails drawing well, rather than pinching as close as possible, with sails shivering. In other words, closer to 80 degrees than 70. This is because Royal Navy sailing qualities reports contain some surprising speeds for frigates sailing close hauled. For instance, 11 knots forthe Lively-class.

I have never in all these sources heard of a ship being fastest with the wind abeam, however the sailing reports I have seen also lack that granular detail. They only ask about performance close-hauled and with the wind aft. Typically the captains want to brag about their best performance, and supply the best speed, invariably with the ship sailing large (although I suspect that this is usually closer to 100 degrees than 145).

Southampton stability: The ship won't fall over until the line falls beneath the Y axis, which is pretty close to 80 degrees for the fully loaded condition (IIRC). Substantially less for the lighter displacement. However, if the wind can heel the ship to the top of the curve, the ship will then capsize unless there is some intervention or the wind slackens.

Leeway: Your simulation already feels spot on. Negligible leeway in moderate conditions is what Harland describes, increasing drastically in heavy weather or when not enough lift is being produced. Also look at the Gustav Adolph sailing report for this. And bear in mind that the Lively, as the apex of British Napoleonic frigate design, was very weatherly.

Other random thoughts: It is possible that your simulation is a little too harsh with the sail blanketing, but I only base that on the visual appearance of the sails (mizzen making the maintopsail go slack, etc). I also really doubt that we could get the frigate to 11 knots close hauled. Heck, even 13 kts requires a gale. But that is a big mystery for me in general, because clearly these speeds were exceptional. In a simulation they would be routine. 

I am reminded of the L'Hermione version of the virtual regatta online game, where the ship maxed out at 7 kts when in reality she has made 13 no problem.

Thank you! Both for the amazing resource, and the thoughts on my questions.

For the leeway,  I've found a similar source that has half a point of leeway "in a topgallant gale" (force 4-5), a point under topsails etc. I assume this was measured when close-hauled.

About the sail blanketting, I think I exaggerated it at one point, since I wanted to get some penalty for having too much sail set before the wind. Now I think this is a matter of difficult steering rather than aerodynamic problems, so I will have another look at it.

Yeah, maybe crank up the drag caused by the rudder to encourage good rig balance.

Notably, in HMS Surprise simulator I could never get any benefit from the historical sailplans that were designed to minimize blanketing.

Something else to consider is the lifting effect of sails. The fore course was prized because it was the only square sail thought to lift the bow rather than drive it down in the water.

Don't forget the ship's trim affects sailing performance, you might have the trim off a little and yet the sails are performing correctly.

That is just beautifully deep in the weeds. Love it !