Periscope detections are hosed

[neilbyrne]

I'm really getting disgusted with having brief exposures of my periscope detected immediately and at very high rates of probability by merchant ships, day or night. Had one detect me last night at 4000 yards in heavy seas. This has been happening for about a week. They get to 4,000 yds and start to zigzag for no apparent reason.
I served on active duty in the USN for 31 years mostly in frigates and destroyers. I had command of a frigate, BRONSTEIN, and a destroyer, BRISCOE. Persicope detections are very hard and you get lots of false contacts. For most of my time as a junior officer, seniors kept telling me that periscope detections by lookouts were a training problem. Then I got a look at about 30 years of SHAREM ASW exercise results and the opportunities vs. detection numbers were just dismal. Obviously, I can’t put classified numbers out here, but suffice it to say that the US Navy has ultimately decided that this is a job for a machine.
A warship has about seven folks looking out full and part time. Three are full time lookouts, port, stbd and aft. Then you have the OOD and JOOD who look out when they can. Last you have the two signalmen who are supposed to be looking out when not signaling; although, in fact, they hardly do. The lookouts have 120 degree sectors that do not overlap. The officers, when they are looking, normally search the forward 180 degrees. The aft lookout has no one else looking where he searches and his primary responsibility is to be the last line of defense for a man who falls overboard, so often he is searching in the near field which the others are not.
In eighteen years of sea duty, I saw less than half a dozen unalerted visual periscope detections that actually turned out to be submarines. Now admittedly, we weren’t worried about being torpedoed, and so our attention was less focused than that of our WWII brethren, but still, not great. This is not to say that I only saw three or so periscopes in 18 years of sea duty. I saw a lot more than that, but they weren’t initial detections. When sonar gets a contact, they call the bridge and CIC requesting a bearing clear or foul report to determine if what they've got is a surface ship or not. The bridge watch standers then look down the bearing sonar gave. Sometimes there’s a periscope there, but these are cued not unalerted detections. If I had to attach an unclassified number to uncued detections, I’d say a warship had no better than a 10% chance, perhaps less, of detecting a periscope that wasn’t way high out of the water and then only in daylight within 4000 yds and merchant ships would certainly do no better. At night, or in low visibility, or heavy seas, forget it; zero percent. The issues at night and in low viz are obvious. In heavy seas the lookout has two problems. First, the eye is most often drawn to the periscope feather, its wake. In heavy seas, foam presides and feathers are insignificant. Second, you can't search with binoculars because you can't steady the field of view. IJN warships had wonderful optical equipment and most destroyers had two sets of big eye mounted binoculars in the pilot house. USN big eyes run to 20X power and are useful for ship recognition, but relatively not for periscope detections because of their narrow field of view.
Surface search radar, until the relatively recent advent of one and two second scan rates in systems like SPQ-9, was only a little better than visual. This was mostly because with six to ten second scan rates, everything as small as a periscope looks to the operator like sea clutter. And we didn’t get good at sea clutter rejection features until after the war. Plus radar sea return clutter is worst right where you’re wanting to look, within 6kyds of own ship.
I wrote two longer posts about ASW for Ducimus about five years ago that contained some of this. In any case, does anyone know where the periscope detection numbers reside so I can examine those and see if what I perceive is happening is in fact the case?