06/20/2010 - What is that switch for?

Over the last two weeks we had a steady flow of visitors. I understand that attendance has been very very good. One weekend we were a little pressed for guides. Typically smaller cohesive groups are the best. When you have few guides and heavy attendance you are forced to have larger tour groups. This takes a little longer and makes it a little difficult to get the groups into all the compartments. It seemed to me that the groups were always of reasonable size.

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What is that switch for?

On 1st glance it is simple - It is that the power switch for the elevation power drive. Next question - Why does to have a Fast and Slow Button? That's very difficult to answer. I didn't know the answer two weeks ago when I was asked, and I don't know today (after spending many hours of research). I asked Tin Rizzuto (the Ship's Superintendent) and Eric Collin (Restoration Coordinator) and they didn't have an answer either. The initial consensus was that we just used a non-standard button during the restoration. During subsequent investigation I found that this wasn't true. I checked other 3" mounts on the Slater that still had the original buttons. I also pulled the design prints (The Slater has a complete set of prints for the 3" mounts). They both indicate a three button configuration.

What I currently BELIEVE: the switch is a quick fix to a problem with the Arma Elevation Power Drive (Mark 31 Mod 0). I believe in the fast setting the elevation drive would respond quicker under director control but it would loose accuracy. With the slower setting the elevation drive would be more accurate, but it's response would be slower. The Trainer position (moving the gun from right to left) does not have this setting. This leads me to believe that in certain situations, perhaps when the ship was rolling heavily, the normal setting of the drive failed to keep the gun on target. When a gun is under director control, it moves quite a bit to compensate for the roll of the ship. Most of the movement is in elevation. When they tried to speed up the drive the accuracy suffered. Rather than scrap the program, someone though of the dual setting as a quick fix.

Unfortunately, I have no documentation to support this theory. I do have a great deal of circumstantial evidence.

I reviewed the 3" Gun Manuals (ORDNANCE PAMPHLET NO. 811, December 22, 1943 which is available on line; and NAVORD OP811, 2nd revision, January 1, 1968, which is available in the Slater's Library). According to the 1943 manual, the 3" guns do not have a power drive. The later manual appears to reference Elevation Indicators - Mark 21. The description of these Indicators seems to be different that the configuration on the Slater.

The manual in the Slater Library (rev 2) refers to Ordalt 2227A (Ordnance Alteration) - "...To provide installation of power drive equipment with automatic control, firing stop mechanism, and hydraulic buffer stops on manually driven mounts MK 22 Mods 0, 4, 17 and 20 converting them to mounts MK 26Mods 0 and 1. ..."

The name plate on the drive has the following details:

• Elevation Power Drive, Mark 31 Mod 0
• Arma Corp, Brooklyn NY
• Serial #177
  
• SK 93744

I ran across this this note on upgrading 3" 50cal with Arma Drive units in the Guide to United States Naval Administrative Histories of World War II. The following excerpt is from the Ordnance Section, Chapter VII: "... The design of 3"/50 power drives was completed in the spring of 1944 by the Arma Corporation, at that time, the bureau of Ordnance was authorized by a directive summary to procure 2,000 power drives for installation on U. S. ships having a battery of three or more 3"/50 guns.[9] However, in the fall of 1944, when the program reached a directive stage for authorization of actual procurement it was decided that 1,000 drives would be sufficient to start the program and the contract for this number was placed with the Arma Corporation. Initial deliveries of power drives were expected during this first quarter of 1945 but due to the difficulty of obtaining a satisfactory design of certain components and to procurement difficulties with subcontractors, the initial supply of 3"/50 power drive equipment was not available until August 1945. Following VJ Day, procurement of drives was reduced to 600; of these, 500 were to be used on 3"/50 caliber mounts Mark 22 scheduled for ships of the post war fleet In which 3" 50 caliber guns are a part of the ultimate approved armament. The remaining 100 units were reserved for the 3M/50 single rapid fire development. ..."

I believe that the USS Slater was one of the 1st ships to be equipped with this Drive, and the difficulties with the program related to the power drives. Those problems led to the power button with the fast/slow setting.

06/06/2010 - DE 5K Walk

On the 6th of June I had planned a 5K walk in downtown Albany. I arranged discounted USS Slater tour coupons for everyone who participated. Unfortunately the 6th of June was a washout, and the DE Docent had to walk alone.

Albany is a great place to walk. I outlined two 5K walks with the USS Slater as a starting point. The 1st is a walk was along the the Corning Preserve. (about 1-1/2 miles). It includes a quick loop to the State Capital. The 2nd walk goes along Broadway, toward the visitor center and the AquaDuck Tour (also finishing with a loop around the capital).

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This week was very hectic. During the week I came to the Slater several times and gave three tours to School Groups. While the groups were rather large, everything went well. The chaperons were great, and the groups were well behaved.

On Sunday despite the rain, I managed to give two tours to very small groups. The 1st group was just two people, who had recently completed a week long bicycle trip along the Erie Canal (basically the length of NY State). The 2nd group was largely comprised of a group of visiting engineers who were in Albany for a training program (of course this led to quite a few technical questions).

What is the range of Sonar? - This is not an easy question to answer because of the impact of environmental factors. Norman Feidman's book on Destroyers in WWII cites 2,000 yards (page 196). U-boat Net has an excellent article on the topic and cites and average of 1,350 meters. These ranges are for active sonar. In contrast ranges for passive sonar can be a high as 100 kilometers for a very noisy sound source like a convoy.

Some other interesting links:

• Wikipedia Article on Sonar
• U-Boat Aces - Passive Sonar
• U-Boat Net - Active Sonar Countermeasures
• USS Slater - Sonar Hut
• USS Slater - Sonar Sound Room (below decks)
• Navy Manual - Naval Sonar, NAVPERS 10884, 1953
• Audio Recording - Sonar
  

5/31/2010 - Memorial Day

It was a beautiful Memorial Day, and Tim and Admiral Paul did a fine job. Immediately after the ceremony I took off for about an hour to do a quick walk. There seemed to be plenty of guides (perhaps 10), which seemed like a sufficient number to handle the crowd. When I got back I learned that they were barely enough. I was a little sorry I didn't stick around. But as soon as I got back I was able to start giving tours.

The 1st group was small, only two visitors. They remembered seeing the USS Slater at the USS Intrepid. The Slater was there from 1993, when it returned to the US from Greece. In 1997 the Slater was relocated to Albany. This video on Navy TV shows the Slater's condition in 1993. I expedited the tour so they could catch a ride on the Dutch Apple. I'm glad to see it cruising again.

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The 2nd group was larger, mostly younger visitors. The tours went fine, and except for the heat everyone had a good time. I was asked a lot about how much things weighed, especially the guns. I have two excellent sources that help with the answers (both from the Historic Naval Ship Association): Gun Mount and Turret Catalog; and Boats of the United States Navy. The USS Slater E-Tour is also an excellent source.

• How much does the 3" Gun weigh? Answer: 6,700 - 7,510 lbs.
• How much does the Motor Whale Boat Weigh? Answer: 5,550 - 8,850 lbs.
• How much does the 50 Cal. Gun weigh? Answer: 83.78 lbs.
• How much does the 20mm Gun weigh? Answer: approx. 1,400 lbs.
• How much does the 40,, Gun weigh? Answer: approx. 14,700 - 14,900 lbs.

Good questions - Hope I answered all of them.