Loot in water despawns too fast. I understand in part why. The ocean is vast and having to keep resources in "play" for an extended period of time might be somehow taxing for the client. I dunno, that's just a guess. A possible solution for this would be ocean currents. Loot in the water would eventually wash up on the beach. Also with this ocean current could be mapped and have a way to predict storms and wind with a bit of skill.
This would also make for another interesting mechanic: Drift.
Right now the Brigantine drifts quite a bit. Sometimes when anchored. This is a bug but it got me thinking. Usually I don't drop anchor at an island because as soon as the ship stops completely, only a storm or a keg will move it if the sails are reefed.
What if a ship that wasn't at anchor would drift onto the rocks or beach making it imperative to anchor unless someone stayed with the ship? The same drift the would make loot drift to wash up on a beach would also move your boat to the shoal.
This also makes for the ability to still have movement when you are becalmed. Yes, NO WIND. I want this to be something to deal with too.
Anyway Ocean currents, could be a neat thing. And would allow for less loot sinking to the abyss.
