To be honest guys, I've been involved with re-fuelling "gas-turbine" engined ships of many nationalities. Never once did we pump across 3,000 tonnes of "avcat" (I seem to recall that the Yanks call it JP4). The only Avcat we sent over was to fuel the aircraft....perhaps 500 cubes at a time. The "Ark", "Impossible" and "Indefensible" were all fuelled with diesel. Exactly the same stuff as you put in your (diesel) car. Sometimes....when needs must....the bottom dregs of the Avcat tanks would be mixed in with the diesel. Much better than the other way about. Similarly, when we had ships using FFO (heavy Furnace Fuel Oil), the Diesel could be used to sort of clean the pipes, mixing it with the FFO. Benefits all round. BY.