Naval gunnery

23rd April 2007, 22:26
A question to RN guys who will know the answer. I don't want to appear dopey because I think I'm going to get an answer that someone is going to say I should have known and it's obvious. But I don't know it and I've wondered about it for donkey's years. So please bear with this ole boy.
For the umpteenth time, yesterday I saw an old black and white movie about sinking the "Bismarck" in WW2. I remember it happening when it happened as a teenager in those days.
Once more the question arose in my mind and it is this:
How can they land a shell on a ship that is travelling at speed from miles away? It just boggles my mind. How do they do it? The ship can be zig zagging and still be hit from miles away.
How are the calculations made? What are the guys in the gun turrets doing for the next salvo that is different from the last salvo? There is a difference of hundreds of yards travelled since the last salvo. What are the guys doing in those few minutes in that turret so the shell travels further or not so far as the last lot fired off. What exactly is being "tweaked" for that shell that it travels a different distance? It can't be the shell though, so it must be the charge that sends it off? What do they do? So many pounds more or less of the explosive that sends the shell on its way? Surely it is not all to do with the angle of the gun barrel is it? There's got to be more to it than that?
There, at last I've asked a question that must be basic stuff to gunners.

Brian Twyman
24th April 2007, 09:27
Hi Old Bosun
Good question, I was a navigator and kept well clear of guns, so expect a reply from an expert soon ! All the data, target range & bearing, own course & speed, target course and speed, wind direction and speed, etc was fed into a mechanical 'fruit machine' which calculated the bearing and angle of the barrels to set, then open fire. Since overtaken by computerised gunnery systems but the principle is the same. Similar machines in submarines to calculate the torpedo firing solution.

K urgess
24th April 2007, 11:14
I don't suppose they just fired "open sights".
Most accounts I've read talk of "bracketting" the enemy then raising or lowering the angle until they hit. Also the gun captain would compensate for the fact that a hot gun shoots differently to a cold one.
The rangefinders would give a distance to target and then it would be "fire when target bears".
Or is that going too far back to the Hornblower era?[=P]
I suppose today they have gyro stabilised weapons and very rarely miss the aiming point.
When was the last seaborne gun battle between capital ships?

24th April 2007, 12:02
Hi Old Bosun

Naval gunnery covers a very wide field and I doubt if it would be possible to put a definitive reply on a thread such as this. Easier to understand, perhaps, when talking about when firing from a fixed location such as a coastal battery but a very different ball game when ships are firing at one another.
Marconi Sahib mentioned Hornblower and although it might not appear so, a degree of 'science' could be found in the gunnery of those days. The French and Spanish tended to aim directly at the primary target being the enemy ship, whereas the Royal Navy sought to get a skimming effect using the wave crests as this gave a more destructive power. I assume this is where the expression to fire "On the uproll" came from.
On the question of the range of the shells themselves, these could be fused. For the smaller shells such as 4" a key was inserted into the fuse mechanism located in the nose of the shell. This could be turned to set the distance at which the shell would explode. I think these were set in yards. In action and when the shells particularly in the ready use racks had been greased to protect them from the elements, an inherent danger was that the key would slip so that an incorrect setting would be made and a shell could explode only a short distance from the ship - heaven help the rating who put a shell on the loading tray in that condition but it has occured on more than one ocasion!
Naval gunnery is a fascinating subject but it is equally both huge and complex!


K urgess
24th April 2007, 13:32
There are a lot of sites dedicated to naval gunnery if you do a search on Google. This one seems good.
Wasn't the gunnery by the British fleet at Jutland abysmal. I seem to remember that the German fleet's hit rate was far greater than the British.
I also read somewhere that it didn't improve between the wars and the fleet exercises in the Med sometimes resulted in not even a target near miss.
Although there is a lot of science involved it seems the first shot was always a ranging one and the elevation was altered to reflect the shot fall. All this was done under the guidance of "Guns", the Gunnery Officer, who was supposed to know his weapons and their capabilities but all guns were still fired independently.
A bit like throwing a stone or casting a fly. Experience and the brain's magical ability to compensate very quickly for untold variables.[=P]

26th April 2007, 11:40
Thanks guys, it's now a lot clearer.
I have been into the website you posted Marconi Sahib. Very informative. Lots to read there.
Thanks again.

yorky jim
26th April 2007, 17:35
A bit before my time ,but i think the same rules applied.
When we did surface shoots,we worked off a thing called a BOX TEN.
First you fired a couple of shells to find the distance ,then you would try to straddle the target.then fire for effect.
Well it went some thing like that,rather rusty these days
My action stations was in the T.S EX royal navy.