[peterloo]

Using Mk.27 to kill merchants... you may be fired by Nimitz by this. Definitely a waste of expensive anti-escort (DD) torpedo

They are designed to blow up the DD's propellor, sonar, rudder or similiar apperatus. Since they are small, they simply contain much less explosive.

So they arn't great anti-ship weapons. They are used solely as a last resort, relying on their stopping power to put a termination on the DD attack run

Next time, save yourself some renown (I know using renown to buy torpedoes is ridiculous), use cheap Mark.14s. That's what a successful submariner does!

p.s. you should NEVER bring 7 Mk. 27 (Fido) for patrol. You should only bring 1~2 of them. For me, 3 is maximum limit. Also, please load them at stern tubes, as those DD attack runs usually comes from your stern side.