Why paddle and screw warships overlapped for decades

How long did paddle-wheel warships last before screw-propelled ships became predominant?

They operated alongside one another for decades while navies compared efficiency, hull integrity, and performance at sea.

The answer stresses that paddlewheels and screw propellers overlapped for decades rather than succeeding one another immediately. Paddlewheels could initially appear more efficient, and they avoided cutting a propeller-shaft opening through the bottom of a wooden hull. Officers also worried that a screw might lift clear of the water in heavy seas. Only repeated trials such as Rattler versus Alecto made the screw's advantages convincing, while a later exchange notes that early steam tugs also continued to tow sailing ships in some operations.