How fresh water changes warship preservation

Does fresh water affect wooden and metal warships differently from salt water?

Both tend to survive longer in fresh water, while wooden hulls also acquire different biological growth because freshwater algae differ from marine fouling.

Fresh water generally improves the survival prospects of both wooden and metal ships. For wooden hulls, the change is not simply less growth but a different biological community. Saltwater and freshwater algae foul the hull in different ways, so environment affects both preservation and the maintenance problems a vessel experiences.