you know it's hard soloing the turret. if you want to know where it is its at section B of beachead next to the big wall next to 2 shipwrecks. but i have an idea. if your level 65 with a aquila galleon or frigate this will work. it MAYBE will work with a marleybone galleon. to solo it you must have 3 mojo potions and careening.
1. go to assault station
2. attack
3. if it heals dont worry it does not heal a lot
4. if your at 70% or 50% less health or less use careening
5. if your so close to death like 10% and have careening regenerating use a mojo potion
6. continue
extra: if you want the thunder storm thing which it gives you rarely this should help you
hope this helped