Remember that ships like Karves can disappear from more than just enemies. If you leave it too far from the shore large swells and storms can cause it to drift out to sea. Sometimes very quickly as well.

I almost lost my latest Karve to that. I have a port in the black forest close to the southern end of my base island to save sailing time to the swamp I'm currently farming. I had it filled with a lot of scrap iron and copper ore. I had just returned from sailing through a pretty intense storm with two serpent attacks so I was eager to get stuff unloaded before something else spawned.

I got the iron off and into a chest at the port dockhouse. At this particular port there is a farther out dock for calm seas and an earthen wall sheltered interior dock for rough seas.

Even at the sheltered dock where I parked the swells were pretty big. By the time I got back to the Karve it had moved a couple feet. I jumped in and started getting some of the copper and by the time I finished I zoomed back out and I was about 10 feet from the dock. I would have had to swim to it had I not caught it. I sailed it further onto a sandy portion and then it actually stayed put (I sat there for a while just in case).

Had I ran the iron back to my base and returned it would have likely been far out to sea and lost.