The same happened to us in B10 (oxsend island), 2 nights in a row now all of our ships are sunk overnight. We are also on EU PVE SIrens call.
Day 1 all ship sof all players (except for a galleon) were sunk around our end of the island.
Day 2 only our ships and that of 1 other company that managed to rebuild were sunk (again the galleon was safe...)
Day 1 we lost:
- 1 sloop
- 1 schooner
- 1 brigantine
Day 2 we lost
- 1 sloop
- 1 Brigantine
Update:
It was another company running into the ships on purpose to sink them. The company name of the company on our server is Phact~ Phact