Odd naval question...

[JSLTIGER]

Hi folks,

I was just wondering if anyone could answer a random naval question for me.

On the Iowa class battleships, turrets two and three have these horizontal slabs of steel that protrude from the after portion of the sides of the turret, kind of like little wings. Turret one lacks these protrusions. Another example of this is on the Japanese Yamato class.

The protrusions can clearly be seen in this pic:

http://upload.wikimedia.org/wikipedia/commons/e/ea/BB61_USS_Iowa_BB61_broadside_USN.jpg

Does anyone know what there purpose is/was and why only two of the three turrets have them? Thanks.

[CaptainMattJ.]

they didnt serve alot of realistic purpose, but they were rangefinders. Not much use though as the FCS and central targeting didnt really need them

[CCIP]

Those would be turret-mounted rangefinders/sights. I believe these were redundant to the central directors anyway, mostly used to cross-check the targeting. That's why they weren't on all turrets - their function was mostly subsumed by directors mounted on the masts.

[Krauter]

Those are optical range finders. I'd assume that they make use of triangulation, i.e.: known distance between the two sights + angle to target = range to target.

Kind of useless considering Iowa can make use of radar for target acquisition. However, I'd assume since technical things naturally break, manual range finders are always a good back up.

Also, the reason why they are positioned on turrets 2 and 3 is because it is assumed that the range difference between turrets 1 and 2 would be negligible compared to the range difference between turrets 2 and 3.

Also 2 is better then 1 :D

[Oberon]

Not just the Iowa, a lot of battleships and battlecruisers had them, including the Hood:

http://www.hmshood.com/ship/dimensions2.jpg

Useful in WWII, well the early part of it, not so useful in the Cold War...

[Sailor Steve]

they didnt serve alot of realistic purpose, but they were rangefinders. Not much use though as the FCS and central targeting didnt really need them
Actually they served a very important purpose. The Fire Control rangfinders could easily be knocked out by one lucky hit, as happened to Bismarck. The the local fire control, while vastly less effective, would be all you had left. That's why every battleship had them since Dreadnought in 1906.

[CaptainMattJ.]

thats true, Steve. But at the time, the Iowa was one of the best, if not the best, battleship classes around. Its incredible speed, range and accuracy (due to the use of radar guided FCS), and its heavy throw weight, it was quite the match for the Yamato, and any other surface ship built during the era.

But, its true that such an event would cripple the battleship without the rangefinders. And the iowa wasnt the only class to be fitted with them, not by a long shot

[Buddahaid]

Here's a plan view of one of Yamato's turrets showing the range finder mechanism.
http://i225.photobucket.com/albums/dd52/sirwinpb/scan0005-2.jpg

[JSLTIGER]

Thanks everybody! That was my guess, but I've always been curious about them and was never able to find out the exact reason for them! :salute::yeah:

[TLAM Strike]

Some ships still have them in FLIR form:

http://img268.imageshack.us/img268/4527/wnrussian5170ak130chaba.th.jpg (http://imageshack.us/photo/my-images/268/wnrussian5170ak130chaba.jpg/)

http://img508.imageshack.us/img508/4060/bayandormkii.th.jpg (http://imageshack.us/photo/my-images/508/bayandormkii.jpg/)

[Sailor Steve]

thats true, Steve. But at the time, the Iowa was one of the best, if not the best, battleship classes around. Its incredible speed, range and accuracy (due to the use of radar guided FCS), and its heavy throw weight, it was quite the match for the Yamato, and any other surface ship built during the era.
The US navy didn't consider them more than a match for Yamato. Have you ever wondered why there were four of them? They never said anything officially but I find it interesting that they were building six, and two of them got cancelled about the same time as Shinano was converted to a carrier.

But, its true that such an event would cripple the battleship without the rangefinders. And the iowa wasnt the only class to be fitted with them, not by a long shot
As I said, every battleship since Dreadnought has had rangefinders in the turrets, because even the shockwave from a near miss can knock the main rangefinder out of alignment, and then there isn't one anymore. This is also why WW2-era battleships had an entire backup Fire Control System in a separate tower.

[CaptainMattJ.]

The US navy didn't consider them more than a match for Yamato. Have you ever wondered why there were four of them? They never said anything officially but I find it interesting that they were building six, and two of them got cancelled about the same time as Shinano was converted to a carrier.


As I said, every battleship since Dreadnought has had rangefinders in the turrets, because even the shockwave from a near miss can knock the main rangefinder out of alignment, and then there isn't one anymore. This is also why WW2-era battleships had an entire backup Fire Control System in a separate tower.
Well, the iowa couldve most certainly held her own in a 1 on 1. Had we not utilized radar guided FCS systems, the battle wouldve most likely have gone to yamato. Her 18.1 inch batteries and thick armor would be the obstacles to overcome. But, under even circumstance, the iowa couldve simply outgunned the Yamato from afar, using her superior top speeds and more accurate shots to pound at her from beyond the accurate range of Yamatos guns.

It sucks that sch an era had to come to an end. THe most powerful Surface vessels ever built to throw slugs are either scrapped or turned into a museum. There should be more survivors, but alas, it takes alot of money maintain one. i would kill to have had alot more surviving museum ships around.

i visited the USS Midway when i was 15 years old. it was such a great experience. Even wowed an old timer who worked down in the engine compartment. He was talking about how the ships name came to be, how another carrier was first named the USS Midway, but was renamed and the now current Midway holds the title. Before he told me the name he said it was the first ship to be sunk by kamikazes in WW2, and so i say, "Oh, i know this one. Isnt that the St. Lo?" He told me that in his 15 years as a volunteer onboard that no one has been able to name that ship, and how the sailors onboard the St. Lo figured that changing the name of a ship was bad luck.

If any of you are ever in the San Diego area, on vacation or whatever, i encourage you to go visit the Midway. Its pretty unique.

[CCIP]

Well, the iowa couldve most certainly held her own in a 1 on 1. Had we not utilized radar guided FCS systems, the battle wouldve most likely have gone to yamato. Her 18.1 inch batteries and thick armor would be the obstacles to overcome. But, under even circumstance, the iowa couldve simply outgunned the Yamato from afar, using her superior top speeds and more accurate shots to pound at her from beyond the accurate range of Yamatos guns.

I think what Steve meant there, though, is that the Navy didn't consider them equal when the ships were designed and built. Noone besides the Japanese really had a very good idea of what Yamato was capable of, as the ship was built and operated in relative secrecy from the outside world. So it was a smart thing to consider an 18" battleship superior to a 16" one, and strategically build more units to be sure to outmatch it.

Hindsight is 20/20 and most analysts after the war, of course, would agree that an Iowa would have beaten the Yamato in a duel. Of course that duel never happened. But in this situation, better to underestimate your own ships than the enemy's!

[Raptor1]

I'm not certain, but didn't the USN only know for certain about the Yamato fielding 18.1" guns after the war was over? I know they were officially designated as 16" guns by the Japanese in order to hide their true caliber.

[CCIP]

I'm not certain, but didn't the USN only know for certain about the Yamato fielding 18.1" guns after the war was over? I know they were officially designated as 16" guns by the Japanese in order to hide their true caliber.

Good point!

A quick search on this led me to a fascinating article:

http://www.navweaps.com/index_tech/tech-084.htm

Indeed the US had a very poor idea of what Yamato was like. It appears they had virtually no idea what the ship even looked like, or how many guns it had until August '42 (!) It was not until early 1944 that they had air recon photographs of the ship to estimate that the guns were larger than 16" and the the ship was larger than 60,000t (as opposed to 35-55,000t estimates in previous years).

Nevertheless, shrewd of them to consider it an extreme threat and counter it with numbers. When in doubt, prepare for worst-case.

[Sailor Steve]

Well, the iowa couldve most certainly held her own in a 1 on 1. Had we not utilized radar guided FCS systems, the battle wouldve most likely have gone to yamato. Her 18.1 inch batteries and thick armor would be the obstacles to overcome. But, under even circumstance, the iowa couldve simply outgunned the Yamato from afar, using her superior top speeds and more accurate shots to pound at her from beyond the accurate range of Yamatos guns.
It's an old truism in warship design that you can't know the actual power of the enemy's guns, so you can only armor against your own. Iowa was armored against her own 16" guns, and Yamato was armored against her own 18" guns, and in both cases that armor was only good at long ranges. Close in there is no armor that can stop any decent shell of comparable value. The good news is that the 18" guns may have carried more powder but actually had slightly inferior penetration.

As for "outgunning from afar", that is by no means guaranteed. Unfortunately superior fire control has never been proven superior. The longest shot ever achieved against a moving target was roughly 26,000 yards, and that was more luck than skill. More likely no one would have been hitting until around 20,000 yards, and at that range Yamato's fire control was perfectly adequate. I agree, an Iowa could likely have "held her own", but the outcome was hardly certain, and that certainty is needed in any naval conflict.

[Torplexed]

Nevertheless, shrewd of them to consider it an extreme threat and counter it with numbers. When in doubt, prepare for worst-case.

The Japanese themselves made some rather shrewd guesses at what the United States was then designing, based largely on the assumption that any U.S. battleship would be designed to fit through the Panama Canal. Japanese intelligence estimated that future U.S. battleships would displace 35,000 tons, would have a speed of 33 knots and a main battery of nine 16" (406mm) guns, and would have a length of 880 feet (268 meters). In fact, the Iowas displaced 45,000 tons, had a speed of 33 knots and main battery of nine 16"/50 guns, and had a waterline length of 860 feet (262 meters). It is fair to say that the Yamatos were designed specifically to outclass the then unknown Iowas.

The Yamatos were also constructed in great secrecy behind giant curtains of sisal rope and mats. Workers were under pain of death to ensure that no plans, drawings or photos of them ever left the dockyard area. The deceptions were so successful that the American Consulate, located across the bay from Musashi's construction site, was completely unaware of her existence during the construction.