What are these clock-like things on the foremasts of American pre-WWII battleships? What did they do? I haven’t seen any on the foremasts of post-Pearl Harbor warships, or on any smaller ships, for that matter.
http://www.pastfoundation.org/Arizona/images/NH76569UTForecastle.jpg
It looks like a clock. Maybe its a clock?
(seems like a handy thing to have where everyone can see if you’re going through timezones quickly so that its difficult for folks to keep track of the time individually)
I will have to do a little digging but IIRC its part of their rangefinding and targeting equipment.
The one in the top picture is only numbered to “9.” What kind of a weird clock is that?
There was a brief period in the 1920’s when “decimal time” was all the rage.
(eh, I got nothing)
Its a signal device to let other ships in the formation know the direction of the enemy. Often in battle, due to smoke, the lead ship might see the enemy ship but following ships in the formation would not. The hands of the clock would indicatie “I am fireing at the ship at 2 oclock.” Developments in radio and radar made the system obsolete.
WRONG! 
They are called “range clocks”. Between the smoke of the guns, and the smoke from the boilers it was actually kind of tough to see the enemy. When one of the ships got the range on the enemy, they set it on the clock. One hand was for thousands of yards, and the other was for hundreds. I assume that the European variety were in meters. The other ships of the line used these ranges to aim their guns.
So what…I missed it by a couple hundred yards?
That’s interesting - thanks. But how would each ship know who had the proper bearings for the enemy? Would the flagship set its “clock” and everyone else would copy that, down the battle line? Would the “null” setting be with both hands straight up?
You can see the bearing to the target by looking at the marks written on the turret base, as seen in your Arizona photo.
I believe that you would set your clock to the range you yourself is shooting at, which may differ by a hundred yards or two, depending on what you know of the difference between you, your flagship/spotter, and the direction of the enemy.
For example, you see that the spotter is telling you that the target is 15,400 yards from him, at a bearing of 310 degrees relative. (That would be on the port, or left side, bow.) You know you are 500 yards astern of the spotter in a “line ahead” formation. Your own range clock will show your own calculated range to the enemy, and your turrets will show a slightly different deflection. (My math skills are way too rusty to give a precise solution here.)
But there were massive “fire table” books, with all this worked out, so that the gunnery officers can have the appropriate solution relatively quickly in the heat of battle.
Yes.
Sometimes you see the same sort of things at old coast defense batteries. In all the smoke and excitement of a battle, having a graphic means of presenting the targeting information was considered important.
Ah, thank you. I understand now. It’s a 1920s style death clock. Going by that, the gunners could rain death on the right spot, rather than killing a lot of mackerel.
Mackerel can be quite dangerous when cornered.
Especially when they are ill-tempered and fitted with frickin’ laser beams.
No, wait, that’s sea bass. Never mind.