The maintenance tradeoff in floating museum ships

Why not preserve museum ships in dry docks that remain filled with water?

Water supports the hull, but corrosion, stagnant water, and the need to drain and clean both ship and dock make the arrangement costly.

A flooded dock distributes hull loads naturally and avoids concentrating weight on a limited set of supports. Water, however, continues to attack underwater plating and therefore does not eliminate hull preservation work. Both ship and dock must be drained periodically so the bottom can be inspected and cleaned. Water left motionless around a museum can also become stagnant and create a public-health problem. The arrangement can preserve structure well, but only by accepting continuing pumping, cleaning, corrosion control, and dock-maintenance costs.