[joegrundman]

This geometrical based technique is great and it really works well within certain parameters. I didn't find it so hard to understand, and it was brilliantly written. I also don't see how it can be cheating, unless the hydrophones just weren't that accurate. But in fact the technique doesn't require especially great hydrophone accuracy. I guess that it was tricky to be sure of your own absloute motion, but again, extreme accuracy isn't needed there.

In fact i think towards the end of the war, sonar based target motion analysis was being used, wasn't it?

Anyway, I've used it to sink a target blind, but i used a longitudinal spread to do so. It's accuracy under favourable conditions is marvellous, although given the chance i prefer to make visual contact before shooting.

For me, there are two kinds of situation where the conditions are not favourable. Firstly when the intial AOB is very small, the changes in bearing at the beginning are too small to be helpful, and then as the target nears the changes are too large to be able to make the third "bearing prediction line" with great accuracy.

Secondly, when the initial AOB is large, or the target is moving fast, the 16 minutes wait time means that you cannot intercept targets which may be reachable using other techniques (unless you are prepared to run on the surface without sonar contacts at all)

Still, this technique has definitely entered my box of tricks, and I love those big circles everywhere!