Crabclaw is the base for settlers and freebooters from The Hann Empire, and one of the least protected ports in Drai Shon. The bay was chosen for its good harbourage, and the fort was built as a bastion of last resort, should the burgeoning town be overrun. Now there is an armed hulk in the middle of the bay, it isn't very mobile, but then no defensive ship at anchor in a bay, is going to be very mobile. Instead, it is crewed by marines and armed with huge siege engines that can smash a ship to pieces quite quickly.