The thing to pay attention to is the fact that THEY AGGRO. Most of the time you can ignore non-undead, non-NM mobs that spawn on the deck of the ship, but this is one case you must watch out for if you are below level 20 and on your own on the ship.
i was a lvl. 75, and i took this little thing on just for the fun of it, next thing a sea horror, sea monk spawn right next to me, me have arti armur on me a draguuun kight, killed it, then got killed by poison, no ide how