The X-4 “Mullet Skiff” was built by Hoffman and his son Ed Jr. in 1980 and was an amphibious development of the earlier X-2 two-seat flying boat, but also slightly larger with side-by-side seating. The 115 hp Lycoming O-235 powered X-4 (N5597N c/n 1) was kept active well into the 2000s by Ed Jr.”
All Aero 