Zig Zag-ing ships ..

[gevers1]

Aye aye. Yesterday, on our way back home to Kiel I spotted a wee tugboat off the Dutch coast. I had one torp left, so I thought I might as well put it to good use. I did the usual routing of plotting a course that put me ahead of the target, lined myself up at a 90 degree angle some 1.5km from the target path, all engines stopped, submerged and waited ... ....

Eventually the chug-chug-chugging of the tug came through the hydrophone, clear as a bell, precisely where I predicted he'd be. I start taking range, speed and AoB measurements and all is going to plan. Until ... for some reason, the tug starts veering all over the shop. He's zig-zagging across the surface like a drunk sailor on shoreleave and my measurements are all to p(l)ot. I followed him around for a while but it was hard to figure out where he was going to be from one minute to the next. So rather than waste an expensive torp, I called off the attack and went home.

So, my question then - how to deal with ships that rather unhelpfully do not sail in straight line ..?