Limit environmental damage to 25%
Chase and take out The Greyhound
When you find The Greyhound she is running into a gauntlet of rocks. You can either directly chase after her or break off to the right. Aim to left from there and you can get at least 2 broadsides in on the greyhound. With the Extra cannon upgrade that will be enough that you can take her down before she gets to her fleet.