How does one attack a zig-zagging convoy?

[Red Devil]

depending on where you are in relation to the convoy. If they are zig zagging it usually means you have been 'detected'.

If convoy is ahead, I do what they called an end around attack, and get ahead of the convoy and begin to approach at standard Speed, then dive to at least 250 feet. I am usually within 2000 yards of convoy, let the lead destroyer go past, and come up to periscope depth. Select about 3 ships if possible, fire and go straight back down, changing course to match convoy. I have it set so that the destroyers are only slight better than 'normal' and wait for detonations if lucky.

I use camera to have a look (it IS only a game eh) if one is crippled then I make course to intercept and position myself then come back up and fire rear tube at it.

Regarding zig zag, sorry I took so long. If within 2000 yards and more than 800 yards, watch ship zig then there is a few seconds where it is going straight before starting to zag at that point I fire, success rate is approx. 75 - 80%.