Possible Ghost Ship Bug
Some players have reported a bug during the encounter:

If you kite the Ghost Ship too far from Skull and Bones Items the encounter area, it may drop aggro and return to its original location, where it could simply spin in place without attacking.
If this happens, you can still defeat the ship by continuously peppering it with attacks, though it might take longer due to its high defenses.
Rewards for Defeating the Maangodin Ghost Ship
When you destroy the Maangodin Ghost Ship, you'll receive two key rewards:

Tarnished Ring: This item completes the Oceans Apart quest when handed to the NPC in The Oubliette.
Ethereal Ashes: A special currency used to Skull and bones items for sale online buy items from the Mysterious Rogue vendor. Here’s what you can purchase with Ethereal Ashes:
Mysterious Chest: Contains random equipment and resources; costs 50 Ethereal Ashes.
Hessel's Outfit Set: A set of clothing and accessories for your character; costs between 10 to 20 Ethereal Ashes.