Reliably killing DDs/other fast ships with RUB and 100%?

[Safe-Keeper]

Only time I ever hit a destroyer was when he was heading straight towards me... For the hell of it I set my aft torp's gyro manual 0, magnetic trigger and shallow depth and it actually hit him. Didnt cripple him, but he did stop chasing me

I love doing that.

Heck, before this certain patch all you had to do was just let the destroyer come after you and then fire your aft torpedo, either an electric one or a gas/steam set to Fast. They never zig-zagged. Now at least the ones that are not "Poor" attack you in an evasive pattern.