Yes, gimpy117! That's what I tried on my last convoy. I normally don't target DDs, but this time I was close to a refit station and i could waste a few fish. I found that using stern shots when pursued worked 4 out of 5 times. When lined up exactly in front if him (i.e. when you both have the same course and the bearing is 180), fire magnetic at a range at no less than 400 feet and no more than 500-600. If you're too close the fish won't have time to arm, and if too far he might be able too evade the torp.
Works well as a bow shot too. Watch "Run Silent Run Deep":
http://www.imdb.com/title/tt0052151/