Torres , I suspect you missed a point.
It was a flying boat base, no amphibians in sight [of the aviation variety.] The majority of RAAF PBY's had their landing gear removed on arrival at Rathmines/Lake Boga and the wheel wells faired over [they needed the reduced weight to achieve their planned missions.] The only RAAF PBY amphibians were air-sea rescue craft and precious few in the Gulf [Bowen and NG mostly?]
If one looks at how to get an Empire boat of the '30's from Darwin to the SE, the bottom of the Gulf gives a reasonable over-land leg to the Pacific waters of the East coast. Hence Karumba. Amazing to stand on the boat ramp at Karumba and think of the flying boats ashore there in the '30/40's.
G'day
