# Battleship question
**URL:** https://boards.straightdope.com/t/battleship-question/412466
**Category:** Factual Questions
**Created:** [July 20, 2007, 12:28am UTC](https://boards.straightdope.com/t/battleship-question/412466 "2007-07-20T00:28:07Z")
**Posts on this page:** 16
**Page:** 1
### Author:  [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)
#### Post date: [July 20, 2007, 12:28am UTC](https://boards.straightdope.com/t/battleship-question/412466/1 "2007-07-20T00:28:07Z")
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](http://www.pastfoundation.org/Arizona/images/NH76569UTForecastle.jpg)
[ ](https://www.chuckhawks.com/uss_oklahoma.jpg)
[ ](http://www.navweaps.com/Weapons/WNUS_16-45_mk1_Maryland_pic.jpg)
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### Author:  [@Malodorous](https://boards.straightdope.com/u/Malodorous)
#### Post date: [July 20, 2007, 12:37am UTC](https://boards.straightdope.com/t/battleship-question/412466/2 "2007-07-20T00:37:04Z")
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)
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### Author:  [@drachillix](https://boards.straightdope.com/u/drachillix)
#### Post date: [July 20, 2007, 12:42am UTC](https://boards.straightdope.com/t/battleship-question/412466/3 "2007-07-20T00:42:16Z")
[QUOTE=Elendil’s Heir]
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](http://www.pastfoundation.org/Arizona/images/NH76569UTForecastle.jpg)
[ ](https://www.chuckhawks.com/uss_oklahoma.jpg)
[ ](https://www.navweaps.com/Weapons/WNUS_16-45_mk1_Maryland_pic.jpg)
[/QUOTE]
I will have to do a little digging but IIRC its part of their rangefinding and targeting equipment.
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### Author:  [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)
#### Post date: [July 20, 2007, 12:43am UTC](https://boards.straightdope.com/t/battleship-question/412466/4 "2007-07-20T00:43:20Z")
[QUOTE=Malodorous]
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)
[/QUOTE]
The one in the top picture is only numbered to “9.” What kind of a weird clock is that?
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### Author:  [@Malodorous](https://boards.straightdope.com/u/Malodorous)
#### Post date: [July 20, 2007, 12:45am UTC](https://boards.straightdope.com/t/battleship-question/412466/5 "2007-07-20T00:45:36Z")
[QUOTE=Elendil’s Heir]
The one in the top picture is only numbered to “9.” What kind of a weird clock is that?
[/QUOTE]
There was a brief period in the 1920’s when “decimal time” was all the rage.
(eh, I got nothing)
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### Author:  [@audit1](https://boards.straightdope.com/u/audit1)
#### Post date: [July 20, 2007, 12:45am UTC](https://boards.straightdope.com/t/battleship-question/412466/6 "2007-07-20T00:45:49Z")
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.
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### Author:  [@drachillix](https://boards.straightdope.com/u/drachillix)
#### Post date: [July 20, 2007, 12:45am UTC](https://boards.straightdope.com/t/battleship-question/412466/7 "2007-07-20T00:45:59Z")
got it
> [@](#):
>
> Concentration Dial or Range Clock - In many ship photographs taken between about 1910 and 1940, there are what appear to be large clocks on the front and rear superstructures or masts. These are actually devices to tell the other ships in the formation at what range that ship is firing at. Together with Declination Marks (see below), these mechanisms allowed the other ships in the formation, whose view of the target may be obscured by fog, gun smoke or funnel smoke, to have their guns at the proper elevation and bearing when their view becomes unobstructed. This greatly reduced the time needed before they were ready to fire. The introduction of radar and better ship-to-ship communication methods in the late 1930s eliminated the need for these devices and they were removed from most ships by the start of World War II or shortly thereafter. For the concentration dial shown here, the small hand represents range in thousands of yards, with 0 = 10,000 yards and 9 = 19,000 yards. The big hand represents range in hundreds of yards.
from here.
> **[Definitions and Information about Naval Guns - NavWeaps](https://www.navweaps.com/Weapons/Gun_Data_p3.php)**
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### Author:  [@treis](https://boards.straightdope.com/u/treis)
#### Post date: [July 20, 2007, 12:47am UTC](https://boards.straightdope.com/t/battleship-question/412466/8 "2007-07-20T00:47:26Z")
[QUOTE=Malodorous]
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)
[/QUOTE]
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.
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### Author:  [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)
#### Post date: [July 20, 2007, 1:10am UTC](https://boards.straightdope.com/t/battleship-question/412466/9 "2007-07-20T01:10:21Z")
**Treis** is right on, here’s a explanation: [http://www.bobhenneman.info/Rangeclocks.htm](http://www.bobhenneman.info/Rangeclocks.htm)
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### Author:  [@drachillix](https://boards.straightdope.com/u/drachillix)
#### Post date: [July 20, 2007, 2:07am UTC](https://boards.straightdope.com/t/battleship-question/412466/10 "2007-07-20T02:07:13Z")
[QUOTE=A.R. Cane]
**Treis** is right on, here’s a explanation: [http://www.bobhenneman.info/Rangeclocks.htm](http://www.bobhenneman.info/Rangeclocks.htm)
[/QUOTE]
So what…I missed it by a couple hundred yards?
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### Author:  [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)
#### Post date: [July 20, 2007, 3:07pm UTC](https://boards.straightdope.com/t/battleship-question/412466/11 "2007-07-20T15:07:26Z")
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?
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### Author:  [@mlees](https://boards.straightdope.com/u/mlees)
#### Post date: [July 20, 2007, 3:26pm UTC](https://boards.straightdope.com/t/battleship-question/412466/12 "2007-07-20T15:26:48Z")
[QUOTE=Elendil’s Heir]
That’s interesting - thanks. But how would each ship know who had the proper bearings for the enemy?
[/quote]
You can see the bearing to the target by looking at the marks written on the turret base, as seen in your _Arizona_ photo.
> [@](#):
>
> Would the flagship set its “clock” and everyone else would copy that, down the battle line?
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.
> [@](#):
>
> Would the “null” setting be with both hands straight up?
Yes.
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### Author:  [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)
#### Post date: [July 20, 2007, 3:31pm UTC](https://boards.straightdope.com/t/battleship-question/412466/13 "2007-07-20T15:31:58Z")
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.
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### Author:  [@AskNott](https://boards.straightdope.com/u/AskNott)
#### Post date: [July 20, 2007, 3:44pm UTC](https://boards.straightdope.com/t/battleship-question/412466/14 "2007-07-20T15:44:17Z")
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.
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### Author:  [@Paul\_in\_Qatar](https://boards.straightdope.com/u/Paul_in_Qatar)
#### Post date: [July 20, 2007, 3:48pm UTC](https://boards.straightdope.com/t/battleship-question/412466/15 "2007-07-20T15:48:44Z")
Mackerel can be quite dangerous when cornered.
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### Author:  [@Ponder\_Stibbons](https://boards.straightdope.com/u/Ponder_Stibbons)
#### Post date: [July 20, 2007, 4:14pm UTC](https://boards.straightdope.com/t/battleship-question/412466/16 "2007-07-20T16:14:28Z")
[QUOTE=Paul in Saudi]
Mackerel can be quite dangerous when cornered.
[/QUOTE]
Especially when they are ill-tempered and fitted with frickin’ laser beams.
No, wait, that’s sea bass. Never mind.