ok will try impact for most of my shots now and at a lesser depth. Thanks for advice guys
I'm not sure why I was setting for magnetic more than impact, I remember reading about magnetic not being a reliable trigger. Also I think I read that the critical hits only come from impact hits the day before yesterday around here somewhere. Perhaps it was my thinking that the explosion under the ship by a magnetic detonation would break it's back.
no aim being available is good to know as well, won't try that now. I hope to get good enough to use manual targetting soon to fix that.
setting sail on my next patrol now to try it out