[Halifax40]

I always take a mix of the two early in the war (nothing's really early when I haven't campaigned passed late 1941). I don't use the selectable torpedo salvos - I set them on my own using the individual tubes. That way I have tubes 1 and 2, always with steam fish, and then tubes 3 and 4 always with electric. I also don't use auto-reload, so I can make sure the right torp type goes into the corresponding tube.

I use setkey for "O" as my conning tower so I can open the tubes manually. As long as you have the first tube selected in the periscope it won't close the other one. So firing tubes 1 and 2, and 3 and 4 is very simple, and actually you can fire them quicker and in more of a rapid succession than the "salvo" option.

*EDIT* - watch the magnetic detonators when doing the above process. I've had 4 electric torpedos now blow up on the way to the target because of the first torpedo's proximity. So sometimes firing really fast to get 2 torpedos to hit within like 2-3 degrees of eachother is not always the best option.