Gunnery.

[Vagabond]

Mind boggling but fascinating. Do you know what additional tools or calculations were used to accommodate the effects of a rolling ship on the sea?

[Bligh]

Those are the sort of things I'm hoping to get answers for.
Rob.

[DeRuyter]

Here are a couple of references I ran across whilst looking up gunnery data. (Related to playing the Naval Action PC game).

http://arc.id.au/CannonBallistics.html

Warning the above abstract includes math that will make your eyes water.

Here is a link to a period source: A Treatise on Artillery by Muller.

https://books.google.com/books/about...d=vylEAAAAYAAJ

The below series of articles contains a raft of information on gunnery. Now granted it is written a magazine devoted to a fictional universe "1632" , but it is non-fiction. The artivles pull together a number of period tests on accuracy and penetration for example.


https://grantvillegazette.com/article/publish-581/

https://grantvillegazette.com/article/publish-596/

[Bligh]

Some great info there Eric.
Thanks.
Although a lot of the info is as you say far more detailed than we need for wargaming
I found this almost immediately. I was particularly interested in how range was estimated on a moving ship at sea.


Standard practice for seventeenth and eighteenth-century naval warfare was to engage at point-blank range (or less).

Point-blank range (PBR) is the furthest that the gun can be assumed to "shoot straight," that is, the range at which the average gunner will use zero elevation. Strictly speaking, it is the range at which the "drop off" equals the height of the muzzle above the water surface, so the projectile will still hit the target. Yes, that means that PBR should vary depending on which deck the gun is mounted on!

There is considerable disagreement as to the actual value. In 1834, Stevens (25) said from a frigate, PBR is 500 yards, and from a "battleship," 700, assuming that the guns are pointed by the "dispart sight at the hammock rails" of a frigate or larger target. In 1828, Beauchant estimated that the 18-, 24-, and 32-pounders, fired from the main deck of a frigate, had a point-blank range of 400 yards with a one-third charge, 300 with a one-quarter, and 250 with one-sixth. However, engagements were more typically at 100–200 yards.


Range and Accuracy.

All else being equal, if you increase the range, you decrease the accuracy. The horizontal extent of an angular error in bearing equals the range times the sine of the angle. The effect of an error in elevation is more complex, thanks to gravity, but the vertical or range error will still increase with range.



Range Estimation.

If the range were great enough that elevating the gun was necessary, then you had to have some way of determining what the range was so you could judge the correct elevation.
The gun captain might, through long experience, be able to estimate visually the range to the target and know the proper elevation to strike it. This depended, of course, in the first instance on the gun captain's visual acuity.
In the late-nineteenth century, American soldiers were required to be able to see a two-foot square black bull's eye on a white background at a distance of 600 yards. (Clowes 385). Training was also important; soldiers would pace off a distance and then study it, or estimate a range and then pace it off. Soldiers were taught that at 600 yards, a man's head was a small round ball, that at 225 yards, his face became distinguishable as a light-colored spot; the eyes can be seen at 80 yards and the proverbial whites of the eyes at 30. (Groome 151; Farrow 697). Presumably, sailors could similarly study the crew of an enemy ship, as well as the visibility of its gun ports, masts, and stays.
In land warfare, visual estimates supposedly had an error of 12–15% at a range of 600–1200 yards. (Hopkins 196). However, at sea, there aren't a succession of fixed reference points, like trees and hills, which you can use to facilitate range estimation. In addition, weather conditions often will degrade visibility. According to Fullam (459), "it is quite impossible to estimate ranges above 2000 yards with anything like sufficient accuracy."
Acoustics: Just as you can estimate how far off a thunderstorm is by timing the interval from lightning flash to thunder rumble, you can count the seconds between the flash and the report of the enemy's guns. This can be made somewhat more precise with an acoustic telemeter; a metal disk is caused to drop through the liquid filling a calibrated tube when the flash is seen, and stopped when the sound is heard. (Cook 593).
Trigonometric Methods: If you know the absolute dimension of any part of the enemy ship, such as the height of its mainmast, you can measure its angular size with the sextant, and calculate the range by trigonometry (or table lookup). Douglas compiled a table of the heights of the parts of French ships of war of various classes. (Douglas 214ff). This works best if the enemy has standardized its warship classes, which unfortunately was not the case in the early-seventeenth century.
Alternatively, as in Buckner's method, you could measure the angle between the enemy's waterline and the horizon; it requires knowledge of the viewer's height above sea level. Use of this method is expedited by what EB11 calls a "depression rangefinder."
These methods were more likely to be used for deliberate shooting by a bow or stern gun during a chase, than for a broadside.
Another trigonometric method is to have observers stationed at the bow and stern of your ship sight the same object and report its bearing. The accuracy of this method depends on the length of your ship, which serves as the baseline (Cook 591). It also required communication between the observers, and wouldn't work if the target were ahead or astern. (Friedman 23).

Rob.

[Bligh]

Here is a little addendum which some of you may be able to work into an AAR or two.
I thought that I was well up on all sorts of early firearms having made them the central part of my College dissertation in 1971. Puckle's machine gun has even been handled by myself during research visit to the Tower Armories.
However it has taken this many years, and my younger son's research to come up with this one.

https://www.youtube.com/watch?v=rCuVMx5h1x0

Rob.

[Bligh]

Here is the Puckle gun clip.

https://www.youtube.com/watch?v=GPC7KiYDshw

Rob.