The tanks of HMS Queen Elizabeth needed to be filled not once, but twice, during her initial sea trials in the North Sea - each time in the former naval base and small port of Invergordon.
Just how much fuel capacity does a 65,000-tonne aircraft carrier have to meet not only her power requirements, but also those of her intended air wing of F-35B stealth fighters and Merlin helicopters?
The answer: 4,000,000 litres of F-76 for the ship and 3,000,000 litres of F-44 for the embarked aircraft.
That's over one million gallons for the ship, three quarters of a million gallons for the air wing.
Or seven million litres in all. You could fill your car up more than 127,000 times with that.
Queen Elizabeth won't be conducting her first replenishment at sea - the preferred method for sustaining naval operations, 'topping up' on the go - until next year; the first of the Tide-class tankers built to resupply her, RFA Tidespring, is undergoing trials in the Channel right now.
"Road tankers were not a practical solution - you would have around 120 lorries thundering across Scotland and into Invergordon for each fuel stop, taking approximately two weeks to complete a single tasking," explained Andy Scraggs, from the RN's Logistics and Infrastructure Division.
The solution? Chartering two British-crewed coastal tankers, the MV Sarnia Cherie and the MV Sarnia Liberty, from the high-performing Defence contractor, James Fisher Everard Ltd, one of the last major British owned and operated tank-ship companies.
Having loaded both cargoes of F-76 fuel at the oil fuel depot in Gosport, each vessel, upon arrival in Scotland, was weighted down at the stern to counter the difficulties posed by the only available berth - a small, steeply shelving mooring - and proceeded to fuel HMS Queen Elizabeth through two 250-metre-long hoses.
The outcome? Two safe, efficient and effective fuelling operations completed on-time, allowing Queen Elizabeth to first resume trials, then head for her home for the next half century.
