Wow, looks like it's just me that does fire salvos. Only for the larger vessels and only ever two eels used. I use it to hedge my bets when I'm in the middle of a convoy (still early years

) and the escorts are bearing down on me. I'd never use it for a lone vessel, hmmm - unless it was a nice juicy carrier...!
Aside from the first time I ever fired a salvo, and missed, I've never forgotton to change the spread angle - you watch, tonight I will