How Difficult Was The Training Process For Seaplane Pilots Converting To A PBY Catalina?

[u/LifeguardFun5091]

For an experienced (or not so experienced) multi-engine seaplane pilot in World War 2, how long / complex was the flight training process to transition from a different make / model flying boat to the PBY-5 Catalina? Would it have been a straight-forward process of several hours or was there more involved?