Where are EITC frigates?

[Stormrunner]

After leaving port in Tortuga, turn toward the left and sail straight out. It shouldn't be long before you see an EITC Corvette (light frigate). They spawn in that area, and there are rarely any higher level ships around.

I must've sunk Corvettes there dozens of times for the various quests. Your best bet is to hit them initially with a broadside from behind. They can turn fairly quickly, however, so do your best to avoid their broadsides.