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.
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 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.