[TorpX]

I'm still not entirely sure everyone understands what I am trying to say. When I use the term 'static search', I don't mean that one spends weeks firmly anchored to the same spot. More like moving 20 or so miles each night, so that you work the patrol area bit by bit. You could, if you wanted, cover the same distance in a single night, but if it is a light traffic area, the odds are you will not come up with anything in a single day, no matter how far you go. Realistically, I think there were many areas where there would be only one or two potential contacts moving through the vicinity each week. Also, I am assuming that there is quite a bit of movement in attack and evasion, whichever search method you use. Perhaps the term 'static search' is not really the most appropriate term. I think we all agree it is preferable to remain surfaced as much as possible. I more or less assumed this in my example, as submerging reduces your detection radius.


I had not thought of it before, but the Kriegsmarine used a variation of this idea. When they wanted to attack a major convoy on the Atlantic route, they had a idea where it would pass, but of course had no way of knowing exactly. Their solution was simple, but effective; arrange a line of U-boats accross the expected path, 15 or so nm apart, and wait for one of them to make contact and report. As long as the boats (pickets) remained fuctional and on station, they were sure to locate the convoy. Donitz called these 'rake operations'. These sorts of tactics may strike many as too "passive", but the passive phase comes to an abrupt end as soon as contact is made.


Here is a slightly different example to further illustrate the concept:

Suppose you are astride a N-S sealane and want to "search" it. I will assume, as before, freighters traveling 9 kts. and a 10 nm detection radius. (This is good for SH 4, since nothing is rendered beyond 10 nm anyway.) If you sit still you will detect 100% of ships in a 20 nm "slice" (10 nm East and 10 West). If you want to move E-W across the sealane (in effect yo-yoing back and forth), how far can you go East or West, without letting ships "slip through"? If you are cruising at 10 kts., you can go 11.1 nm on either side, and still make sure nothing gets by in the center. Why do I say 11.1 nm? Because in the time it takes you to go 11.1 nm East and 11.1 nm West (back where you started), an enemy ship could move through the 20 nm deep band you are searching. Going any farther would allow some ships to slip past. Following this plan, you will detect 100% of ships within this 22.2 nm zone, and some of the ships within a 10 nm 'fringe' zone on either side. If you wanted to cruise at 15 kts., the figures would be 33.3 nm with a 10 nm 'fringe'.


The point I'm trying to make here is not that a dynamic search is no good, but only that it doesn't necessarily improve your chances as much as it would appear.