In message
,
David E. Powell writes
Such as lightweight torpedoes on destroyers and frigates, where the
ship would already be in rane for a Submarine with heavyweight
torpedoes?

Detection ranges can be unpredictable; the submarine may be trying to
sneak past the escort to get a shot at the HVU it's protecting; and, if
the escort's attacked or it detects a submarine torpedo firing, an
immediate countershot may discompose the submarine, which will reduce
the effectiveness of a wire-guided torpedo (a lively torpedo
countermeasure manoeuvre is likely to break the guidance wire, so when
the torpedo goes for the "ooh, shiny!" acoustic decoy it can't be nudged
back onto the real target).

Again, the DD/FF is an obstacle in the submarine's path, rather than a
primary target: since it's likely to be carrying lightweight torpedoes
in its air weapons store, why not give it the option to launch them? (On
a Type 23 they're fired straight from the magazine: the torpedo room has
two tubes either beam plus a door to the hangar)

--
He thinks too much, such men are dangerous.

Paul J. Adam