Could a panokseon become a turtle ship?

Was the turtle ship different from a panokseon, and could one be converted quickly?

Yes, it was a distinct covered design, but Yi may have prepared panokseon-type hulls and materials in advance for rapid conversion.

A turtle ship was more than an unchanged panokseon. It required a different upper structure, a covered deck, weapons, and additional material. Yet Yi had only about a year in command, making a wholly new construction effort after Okpo difficult to reconcile with the three-week interval before Sacheon. One working theory is that suitable hulls and resources had already been prepared so they could be converted quickly once war began.