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I don't think anyone will argue with the fact that the mass of projectiles a Napoleonic era warship could fire at its opponent mattered - a 36 pound ball will naturally tend to cause more damage and more splinters than a 6 pound one. However, I couldn't find much detail on how much. While the tests of cannons on hull replicas and accounts of the actual engagements I found say a lot about the naval artillery of the time in general, I haven't found any tests of multiple guns on the same target, and in the battle accounts there's often too many other factors at play.

In short the question is what is the general correlation between the mass of a roundshot and the damage it can cause to the crew (mostly by splinters) and the ship's components, assuming same conditions (same impact velocity, target, ...).

The question is purely about what happens when the roundshot hits; things not directly related to this can be left out.

There's no need to go into excessive details; even something like whether 2× the mass will generally cause less/exactly/more than 2× of a certain form of OUCH to crew/ship is precise enough, though feel free to add some detail if you deem it important to the topic, and I encourage you to, if possible, add some historical examples or accounts you think show this well enough to get the general idea.

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    Migrate to physics.stackexchange.com
    – SPavel
    Oct 16, 2023 at 19:04
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    I don't think that it's a straightforward relationship between calibre and damage caused. Over-penetration could be almost as much of a problem as under-penetration. Ideally, the cannonball will bounce around inside the ship, killing the crew, dismounting guns and weakening the ship's structure - and almost any Napoleonic naval cannon is capable of doing a lot of damage if it can manage that.
    – Steve Bird
    Oct 16, 2023 at 19:14
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    And then there's "spalling": the high-velocity rain of wooden shards created from a cannon-ball's impact... Oct 16, 2023 at 20:17
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    It is... complicated. A cannon ball with twice the mass would have needed more powder and a heavier gun to get to the same speed, and would probably taken longer to load. If the muzzle speed was the same, the ball with double the mass would have double the kinetic speed. But it would lose proportionally less of its speed and kinetic energy than the lighter ball, and so it would have a longer range. And that is only to begin with.
    – SJuan76
    Oct 16, 2023 at 20:26
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    @SJuan76 the size of the ball matters way less for reload speed than the length of the barrel it has to be shoved down. That's why, e.g. the 68 lb carronades on the Victory, fired faster than her 24lb long guns.
    – Eugene
    Oct 17, 2023 at 19:02

4 Answers 4

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At the simplest level, yes, a larger shot will have better penetration than smaller shot for the same muzzle velocity or for a given powder charge. The amount of damage/casualties actually caused will vary depending on where the shot strikes, if it rebounds around the cabin or penetrates the opposite side, and how much splintering takes place.

The table below gives a comparison of the penetration (of solid elm) achievable by guns of various calibres and charge weights.

42 pounder (10 ft barrel):

Charge Velocity (ft/s) Penetration (ins)
21 lbs 1600 49.5
14 lbs 1300 32.5
10 lbs 8 oz 1130 24.5
7 lbs 925 16.5
3 lbs 8 oz 650 8.5

32 pounder (10 ft barrel):

Charge Velocity (ft/s) Penetration (ins)
16 lbs 1600 45.0
10 lbs 14 oz 1300 29.66
8 lbs 1130 22.5
5 lbs 4 oz 925 15.0
2 lbs 10 oz 650 7.33

9 pounder (8.5 ft barrel):

Charge Velocity (ft/s) Penetration (ins)
4 lbs 8 oz 1600 29.5
3 lbs 1300 19.5
2 lbs 4 oz 1130 14.66
1 lbs 8 oz 925 9.83
12 oz 650 4.75

6 pounder (7.5 ft barrel):

Charge Velocity (ft/s) Penetration (ins)
3 lbs 1600 25.8
2 lbs 1300 17
1 lbs 8 oz 1130 13

For comparison, the table below gives a sample of the thickness of wood in various ship classes. Obviously, the penetration will depend on the angle that the shot strikes the target. As the angle increases from the perpendicular, the greater the apparent thickness of the wood becomes.

Rating Location Thickness (ins)
1st Rate Load line 28.0
Upper deck 21.0
2nd Rate Load line 26.25
Upper deck 20.0
3rd Rate Load line 24.0
Upper deck 18.25
Frigate Load line 20.0
Upper deck 14.5
Corvette Load line 17.5
Upper deck 14.0

Given the space, this is a very simple overview and a detailed analysis would take a chapter or two (or possibly a book of its own).

Source: The Naval Gunner, Lt. T. S. Beauchant (Devonport, 1828), pg 133-134

Once the shot has entered the ship, what happens will vary depending on where the shot hit. Unfortunately, there seems to have been little contemporary experimental data (quite possibly because of the difficulty of realistically modelling the environment and recording the effects) to work from. So what we know is almost entirely from anecdotal reports. [The modern recreations all seem to work with comparatively small calibre cannon firing into fairly small, thin hull sections which don't really simulate the effects of a strike on an enclosed gun deck]

A strike at the waterline will possibly allow water to enter the ship. Patching the hole would then become a priority because a sinking ship loses the ability to fight (as men are taken to man the pumps) and manoeuvre effectively. A strike at just the right point at the waterline might just enter the magazine and if it hits something capable of creating a spark - boom (although great care was usually taken to ensure that there was nothing that could spark in there).

A hit into the deck space will have the possibility of killing men directly, dismounting cannon from their carriages and damaging the masts and rigging (one way of dismasting a ship). If the attacking ship could put itself across the bow or stern of the target, then shot could potentially travel the entire length of the gun deck killing anyone in the way, with an increased chance of dismounting one or more guns.

Indirectly, wood 'splinters' (that could actually be several feet long) would shower anyone in their vicinity, maiming or killing those they struck (and infection would then kill many of the injured). The exact nature of the splintering would depend on both the size of the shot and the type of wood used in the hull. Counter-intuitively, lower velocity shot from carronades was said to create more splinters (which earned them the nickname "smashers") than the long guns.

If the shot hit a gunpowder cask or killed someone handling one, then gunpowder could be spread across the deck where any source of ignition could result in a rapidly spreading fire (obviously care was taken to avoid this but in a crowded, dark, rolling gun deck accidents can happen). Like flooding, once a fire starts it becomes a priority to put out because of the risk to the structure of the ship and the possibility that the fire might reach the magazines with immediately fatal consequences. In fact, there are accounts from Trafalgar of the crews of enemy ships helping fight fires because of the risk of the fire spreading to their own ship or causing an explosion that could sink both ships.

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    Perhaps extend final sentence into something like: "As the angle increases from the perpendicular, the greater the apparent thickness of the wood becomes; and the less work (in hull damage) done by the projectile on that increased apparent thickness". Both effects are significant. Oct 17, 2023 at 0:49
  • Just doing some mental linear regression. The penetration of a given cannon is almost exactly proportional to weight of the charge. The velocity also seems to nicely fit linearly with the charge but with a non-zero interception term. I would need to put this into an actual statistics software to compare the different guns to each other.
    – quarague
    Oct 17, 2023 at 8:33
  • Wowee penetrating four feet into solid elm is quite some impulse for a 200 year old weapon. Oct 17, 2023 at 9:05
  • While I wasn't looking for penetration this is still a great answer, especially regarding the huge difference the charge makes which I didn't think of until now. Which charges would be the most common?
    – Kugelblitz
    Oct 17, 2023 at 13:08
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    @quarague yeah, but reasons to vary the shot size include: 1. there's only so much powder you can cram behind a given ball, 2. a heavier shot will "carry further", i.e. lose less velocity over a long distance, 3. overpenetration: a big shot that rattles around in the target is more damaging than a smaller one that makes two clean holes.
    – hobbs
    Oct 17, 2023 at 14:05
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As a supplement to @SteveBird 's fine answer, I took the values he supplied, passed them through the R and generated some plots using ggplot.

In all cases, solid shot like these, while perfectly capable of killing people, were primarily used as anti-infrastructure rather than anti-personnel measures. There were specialist shot for damaging rigging (chain shot) and as anti-personnel (canister), as well as various exploding shells.

Note barrel length has some role in this, the 42 and 32 lb cannon both had a 10 foot barrel, but the 9 and 6 lb cannon were shorter. A longer barrel leads to greater muzzle velocity, as more pressure can be built up behind the ball. At what point friction counteracts this, I don't know, and it may not have been a problem for cannon, as a longer barrel would be much heavier and more unwieldy; exactly what you don't want in a confined space like a ship, not to mention the effects of extra weight on things like ship-speed and maneuverability.

The first is charge vs velocity. Unsurprisingly, a lighter ball will have a greater velocity with a smaller charge - inertia at play.

Charge vs Velocity

Second, as you can see, and might expect, with a more massive ball you get significantly more penetration, however, in some circumstances, the difference between the 32 lb and 42 lb balls indicate that a the smaller ball is more efficient for a given charge, though the difference of nearly 5 inches of solid Elm at the top end was more than worth it, I suspect.

Charge vs Penetration

Last is muzzle velocity vs penetration. Simply put, a heavier ball, travelling at the same velocity as a lighter ball will penetrate further. Not surprising - inertia again!.

Velocity vs Penetration

These data show that, up to a certain point at least, heavier cannon were better at damaging than lighter ones. There will be some point at which too heavy comes into play in terms of rate of fire, manhandling and boat balance/speed/maneuverability, but these are all factors which are outside the scope of the question.

TL, DR: Bring out the Big Guns!

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As a supplement to @bob1 's fine answer, which already is "a supplement to @SteveBird 's fine answer"

You might want to plot with the pounder on the x-axis:

enter image description here

(x-axis: pounder in pounds; y-axis: penetration in inches; legend: velocity in ft/s)

We can see once again that big ammunitions are not that efficient (in penetration/pound): slope < 1 & Y-intercept > 0.

However, the lines are for a single velocity and you might want to check what is the normal/average charge (and so velocity) for each gun.

And finally about the "too much incovenience for the biggest cannon/ammo", the point is to make the opponent unable to fire back as fast as possible, hence bigger ships with more and bigger cannons (at the cost of speed or manoeuvrability unfortunaltely, which also play a big role in combats).

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  • Can you add units to the legend? Oct 19, 2023 at 3:07
  • @AstorFlorida post edited and clarifications added as text below the plot
    – lu_ciol_
    Oct 20, 2023 at 9:01
  • Thanks! II like this answer very much. What are the units in the legend? m/s ? km/h ? mph? Oct 20, 2023 at 10:02
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More damage (to a component) won't necessarily mean more damage (to the ship).

From the data in Steve Bird's answer, all of the calibres could penetrate a couple of feet given enough charge weight.

So, if any of those cannonballs hit a mast or a person it/they are almost certainly toast. If they hit the hull above the water line, and nothing else, a smaller or bigger hole is only going to affect how much wood is needed to repair it. Although a bigger hole will create more shrapnel.

An increased size will mean a greater chance of hitting something important. But weight increases twice as fast as surface area so you're probably better off fitting more smaller cannons and firing more cannonballs. This also applies to the shrapnel.

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    1) You have grossly misrepresented the Square-Cube law you quote in the final paragraph. 2) You have completely misunderstood the key constraint on calibre for a ship-of-the-line: waterline length, or alternatively available gun ports. It's all about getting the heaviest calibre guns possible on just both sides of two and a half decks, while keeping the vessel sea and battle worthy. Reducing gun calibre below what is possible to carry is idiocy. Oct 17, 2023 at 13:38
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    Further, it was important to have heavier calibres on the second gun deck as well as on the lower, as the latter would be unavailable for battle use in heavy weather, due to the risk of swamping the ship through open gunports so close to the waterline. Oct 17, 2023 at 13:41

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