Can't remeber all the ship types but the largest pirate fleet has been 4 full stacks. Had to send out 3 separate stacks of high end ships to finish them off, (lost the first two), and the last had to go for repairs once before finally wiping them out. The first two broke up their grouping, then could take them on in a reasonable manner.

Most fun I've had in naval battles, was certain I was going to wipe them all out no problem everytime so the loss of two stacks came as something of a shock.