Real Submarine Technology & History Q&A

[DaveyJ576]

Originally Posted by LukeFF

Norman Friedman mentions that two boats of the S-42 class received "Mark 14 torpedo directors" in their modernization overhaul in 1943. By that term, does he mean TBTs and if so, how did they feed data to the torpedoes?

Luke,

I believe the brief mention on page 145 in Friedman's U.S. Submarines Through 1945 to be a typo. I too thought he might have been refering to the Target Bearing Transmitters (TBT) mounted on the bridge to send bearing info to the tracking party. Research showed, however that the TBT was designated Mk 8.

More poking around showed that there was a Mk 14 gun director (or gun sight) that was used for 20 and 40 mm guns. This gyro stabilized sight produced a lead/lag angle for the guns which greaty improved accuracy. This is probably what Friedman was refering to. It could be that an editor mistook the Mk 14 reference to mean torpedo and changed the text.

The TBT's are essentially a pressure proof binocular mounted on a gyro repeater display. As the TBT is rotated to the target bearing, a transmitter mounted underneath sends an electrical signal to a bearing repeater in the conning tower and that repeater shows the bearing to which the TBT is pointed. On the left side of the TBT is a simple buzzer button that when pressed makes a sound in the conning tower indicating that the TBT is on the target bearing, and that the fire control team needs to use that bearing in their solution. That data is then manually fed into the TDC by the operator.

BTW, I haven't confirmed it yet, but I don't believe that the S-boats were ever fitted with TDC's. Both the control room and the conning tower were small and jam packed with gear and even the later models of the TDC would have been too big to fit. The crews of the S-boats continued to use hand held manual slide rule style devices known as the "Is-Was" and the "Banjo" to determine fire control solutions until the end of the war. An experienced and well drilled tracking party could still do well with these devices, and they were retained on the fleet boats as back up in case the TDC went down.

[Nisgeis]

I have not heard of any S-Boats receiving a TDC. A TBT is only a measuring instrument and cannot really be confused with a torpedo director, in terms of calculated output. Torpedo directors were common on destroyers (with torpedo tubes) and the director would sit atop the tubes. They were nowhere near as advanced as a TDC, but I think it's possible that the 'Mark 14 torpedo director' was in fact a torpedo director whose mark was 14, rather than a director whose function was to direct mark 14 torpedoes (especially as the S-boats were a bit short). At the start of the war the torpedo directors were up to mark 7(?) and by 1947 they were at mark 27, so the number fits.

Isn't it more feasable that it refers to a torpedo director system that is a fire control system for torpedoes, rather than a fire control system for guns, which would be of very limitted value on an S-Boat, especially in 1943, before deck gun fire control systems were put aboard fleet boats with the guns to utilise them.

[DaveyJ576]

Originally Posted by Nisgeis

Torpedo directors were common on destroyers (with torpedo tubes) and the director would sit atop the tubes. They were nowhere near as advanced as a TDC, but I think it's possible that the 'Mark 14 torpedo director' was in fact a torpedo director whose mark was 14, rather than a director whose function was to direct mark 14 torpedoes (especially as the S-boats were a bit short). At the start of the war the torpedo directors were up to mark 7(?) and by 1947 they were at mark 27, so the number fits.

Isn't it more feasable that it refers to a torpedo director system that is a fire control system for torpedoes, rather than a fire control system for guns, which would be of very limitted value on an S-Boat, especially in 1943, before deck gun fire control systems were put aboard fleet boats with the guns to utilise them.

I considered this very issue as I was researching my earlier post. One thing that was not mentioned was that in the same sentence Norman Friedman mentioned that the Mk 14 torpedo director was "a modification also extended to many R-boats." The R-boats were a smaller precursor to the S-boats. None of them made war patrols and were used strictly for training stateside. I asked myself the question: Why put a fairly sophisticated piece of equipment on a boat that would not go into combat? These torpedo directors would have been unique to the R-boats and just 2 S-boats. They would have been of little value to a non-combat boat, and as these boats were used to train fleet boat crews, the directors would have been of NO value as a training device as they did not exist on the TDC equipped fleet boats! This argument is what led me down the path to a simple typo.

However, I fully admit that the same line of logic could be applied to the existence of these directors as gun directors. The gun director typo just made more sense to me.

This issue is illustrative of the choppy nature of Norman Friedman's writing style. Many times he drops these interesting research morsels, then utterly fails to explain them! It is kind of frustrating and will leave you scratching your head.

[Nisgeis]

Yeah I know what you mean, he's very brief in some areas and packs in a whole chapters worth into a paragraph. Sometimes reading the notes section is more revealing that what he put in the main text. That book needs to be much larger :-).

The thing that struck me about the gun directors was from something I read in 'The Fleet Type Submarine in the US Navy' where he talks about a stable element and a gun director (I think it's a gun director anyway) being installed in Sennet, Lagarto and erm Razorback(?) in March 1945. The way it is written, it implies that a fire control device was needed to co-ordinate the two deck guns as it was no longer one gun captain aiming one gun. That's the only reason I have for not thinking it means a gun director at that date, as it doesn't seem they were needed. Was it the Narwahl that had dual 6" guns? I wonder if that had a fire control system, or was manned as two seperate guns.

I find this detective an deductive stuff fascinating, as it could be a year from now and I'll read something that points me in the right direction. It's also amazing that for technology not that old, it's already a bit of a mystery. Th einformation is probably out there somewhere in some archive.

[Nuc]

Originally Posted by DaveyJ576

The R-boats were a smaller precursor to the S-boats. None of them made war patrols and were used strictly for training stateside.

I don't think that is strictly true. I believe several R boats made Anti U-Boat patrols out of Bermuda, Key West and St Thomas. Dudley Morton in command of R5 attacked a U-boat on February 10, 1942. See Roscoe p 89-91

[DaveyJ576]

Originally Posted by DaveyJ576

I believe several R boats made Anti U-Boat patrols out of Bermuda, Key West and St Thomas. Dudley Morton in command of R5 attacked a U-boat on February 10, 1942. See Roscoe p 89-91

Nuc,

You are absolutely correct. I was going a bit fast when I wrote that post. My intent was to show that none of the R-boats made any Pacific war patrols. The USN never took the Atlantic anti U-boat submarine patrols very seriously and relied on air and surface ship patrols to do the job. This is why the sub force mostly assigned the ancient R-boats and the obsolescent S-boats to this job. These boats could be spared. The Atlantic fleet boats spent much more time in training exercises than they did on patrol. While they did get a few upgrades, they never got the much more extensive upgrades that some of the S-boats in the Pacific theater received.

[DaveyJ576]

Originally Posted by Nisgeis

Was it the Narwahl that had dual 6" guns? I wonder if that had a fire control system, or was manned as two seperate guns.

Actually, Argonaut (SS-166), Narwhal (SS-167), and Nautilus (SS-168) all had the big 6"/53 cal guns. As far as I can tell, there was no central fire control system, each gun was pointed and trained separately. This limited their usefulness somewhat. The shells were big and heavy enough that power hoists had to be installed to lift the ammo from the magazine underneath crew's mess to the gun platforms on deck.

Narwhal's guns still exist. They are on display outside of Morton Hall on the Submarine Base in Groton, CT. Check out this link: www.navsource.org/archives/08/0816718.jpg

I took this pic when I was at the base last year. They are damned impressive.

I sure wish the game developers had included these three boats in SHIV.

[Torplexed]

Originally Posted by DaveyJ576

I sure wish the game developers had included these three boats in SHIV.

I wish they had too, although with a surface battery like that I probably would succumb to the temptation to tackle targets on the surface I probably shouldn't. Going by your picture of the Narwhal's guns I'd be real nervous about patronizing that Subway's sandwich shop across the street. Was Argonaut the only one fitted to lay mines, or could all three?

[DaveyJ576]

Originally Posted by Torplexed

Was Argonaut the only one fitted to lay mines, or could all three?

Of those three boats, only Argonaut was equipped specifically as a minelayer. She had two large tubes aft for the 40 inch wide Mk 11 mines. She could carry 60 of them and they were developed especially for her. The mine launching and compensation system was complex and required constant training and careful maintenance. The minelaying mission was never a popular one with submariners and the system fell out of use by WWII. Argonaut was eventually refitted with two standard 21 inch torpedo tubes mounted externally to the hull. Narwhal and Nautilus were outfitted from the start as cruiser submarines and had two standard torpedo tubes were Argonaut had her mine tubes.

Mine R&D had, by the start of the war, developed a mine capable of being launched from the standard 21 inch torpedo tubes of any submarine. Thus the whole need for a specialized minelaying submarine evaporated. Indeed, the torpedo shortage in the early months of the war forced some of the fleet boats to go on patrol with partial mine loadouts.

[eljeffo41]

How long did a fleet boats battery last?Did they have to cut a hole in the hull to replace them?I would imagine the individual batteries were very large and heavy!Probably not a job anyone would look forward to!

[DaveyJ576]

Originally Posted by eljeffo41

How long did a fleet boats battery last? Did they have to cut a hole in the hull to replace them? I would imagine the individual batteries were very large and heavy! Probably not a job anyone would look forward to!

A fleet boat battery cell was 4.5 feet high, and 21 x 15 inches wide. It weighed a little over 3/4 of a ton. Not your average Duracell by any means! There were 252 of these cells in two separate battery wells. Normal life span was about two years, but this could vary depending on operating conditions.

These Exide and Gould lead acid batteries achieved this fairly long life at the expense of power output. Their German counterparts had a much higher output resulting in a greater submerged speed. But, the German batteries took longer to charge, they produced high amounts of hydrogen gas, and had a much shorter life (and thus were much more expensive).

The cells themselves are contained within a multi-layer hard rubber jar. The inner layer is an impermeable soft rubber membrane about the thickness of a balloon. This membrane contains the battery acid if the outer layer of hard rubber cracks due to battle damage. This type of jar greatly increased the reliability of the battery and thus the survivability of the submarine and was a key feature of the USN boats.

Changing out a battery was normally only done during overhauls in the states. A section of the walking deck in the forward and after battery had to be removed and each indivdual cell craned out one by one. In the after battery they were simply hauled up through the access hatch and off the boat. The forward battery, however, did not have a hatch and thus a hole was cut in the top of the pressure hull so that the cells could be removed. This was a long, difficult, and somewhat dangerous process and was only done when really necessary.

[gimpy117]

Q: I was told by my grandfather US subs had an early IFF system...is this true??

[DaveyJ576]

Originally Posted by gimpy117

Q: I was told by my grandfather US subs had an early IFF system...is this true??

Yes, it is true, but only to a certain extent.

For those that do not know, IFF stands for Identification Friend or Foe. It is a radar/transponder based system designed to determine if a particular unit (ship or plane) is friendly. A radar type pulse of a specified frequency is sent out from your unit to the approaching unit. The pulse activates a transponder and it pulses back at a different frequency. This pulse is received at the sending unit and identifies it as friendly. While better than nothing, the system is not perfect as it will not positively identify a unit as unfriendly. If no pulse is received from the transponder, the contact is considered unfriendly. However, a friendly unit's transponder may be out of commission or damaged in battle and thus unable to respond.

The Naval Research Laboratory developed the first IFF system, the XAE, as early as 1937. Radar in general was in its infancy at the time and radar systems were poorly understood and mistrusted by the USN in general until about late 1942. The exception was the Submarine Service. It was seen as a valuable tool and was quickly embraced as soon as the technology became available. IFF systems were slower to be introduced, with the first system installed on the USS Angler (SS-240) in late 1943. Many boats still did not have IFF installed at the end of the war.

[Arclight]

Probably a dumb question, but was it possible to exchange torpedoes between the fore and aft torpedo rooms?

I've been wondering that since SH3; U-boats had external storage for fish, which made me wonder if it was feesible to cart one around the conning tower across the deck. Doubt it was possible to cart one the length of the sub internally.

[Morpheus]

Originally Posted by Arclight

Probably a dumb question, but was it possible to exchange torpedoes between the fore and aft torpedo rooms?

No. Neither on U.S. Subs, nor german Subs ...