FT-Subs?

I was just wondering if anybody uses subs, and how do you play/design
them?
I was thinking of either using a cloaking device, or ECM to allow them
to
hide in a system, and take pot shots at merchantmen etc. Equiping them
with
a Cl.1 bat and a P.Torp (or a missile) with a single PDS would be useful
against merchantmen while being cheap.	Just thinking of a way to make
small
ships useful in a strategic sence in comercial warfare (like the wolf
packs
in WW2).

Any ideas for this?