Lol, yes, this is sad. We had the same last week, finished a fort, started collecting loot, when a clever sailsman thought it would be a good idea to move the ship just a bit, to be able to use the harpoon for taking loot on board. He used the anchor to stop the ship, the rest is history.
This sucks.
Apparently Rare uses anchoring as an indication that you are in a safe place and have nothing to do. But this is often not the case! This indication is insufficient.
They could simply mitigate it by excluding a server migration for a short time that starts after certain events, such as
- Kraken was just killed by / near you.
- Megalodon was just killed by / near you .
- Ship just been sunk by / near you.
- Fort has just been conquered by / near you.
Nevertheless, I can think of many other constellations that show that the indication "anchoring == ready for server migration" is completely inadequate.