IMO, use arm sailors for torpedoes, and then switch them to AA sailors when you
get your first ship with decent AA (Cleve or Balt)

You will lose some AAW by making a later switch, but you will gain a lot more reload.

Torpedo Man class for the US is not worth it -- it's a dead end job. While torpedos are
useful on the Fletcher/Gearing/Somers after that they're no longer effectively useful
(Brooklyn and Cleveland being the exception). Nobody loads torpedo launchers on higher
level ships meaning that you'll waste a lot of experience training a sailor that will
eventually become useless to you.

Support or Special Forces personnel can man torpedo launchers before they come to their
first class change (starting at level 25). Unlike torpedo men, however, they're still
useful to continue to level up as repairmen, pilots, or whatnot -- they become an asset
whereas the torpedo men sit idle in your sailor list.

The difference between the Mark 11 and Mark 12 torpedos (~20% more range on "fast" speed)
isn't important enough to warrant a focus on the Mark 12's or the higher level sailors
that they require to man them. The Mark 15's pack quite a wallop but you'd need to
dedicate sailors all the way to level 32 to use them and a 12000 damage torpedo is pretty
overkill for use in fending off DD's attacking your Brooklyn.

Hold off for as long as possible, they will ONLY be able to be used in torp launchers,
and will ONLY gain exp from torping. So it will take forever to lvl them up once you
switch them to torpers, unless you constantly torp, and even then they will get very
little exp.

if you want to use torps then it is a good idea to get one. Most high lvl ships use AA to
my knowledge so maybe that could be an option.