I estimate QM2 would get a little over 30 feet per gallon of fuel at 29 knots. Here is how I calculated that based on the 2022 Tech Spec:

Daily consumption at 29 knots ~= 261 tonnes Heavy Fuel Oil (HFO) plus 237 tonnes Marine Gas Oil (MGO) ~= 10.9 tonne/hr HFO plus 9.9 tonne/hr MGO.

1 tonne = 1000 kg = 1000 liters water ~= 909 liters HFO ~= 1150 liters MGO.

1 liter = 0.2642 US gal, 1 tonne HFO ~= 240 gal, 1 tonne MGO ~= 304 gal .

(10.9)(240) = 2616 gal/hr HFO plus (9.9)(304) = 3010 gal/hr MGO = 5626 gal/hr total.

29 knots = 29 nm/hr = 33.35 mph = 176088 ft/hr, therefore QM2 “mpg” @ 29 kts ~= 176088/5626 = 31.3 ft/gal.

So, because in general fuel consumption varies with the cube of speed, QM2’s “mileage” when cruising at 14 knots will be ~278 ft/gal.

Below is the latest version of the Technical Specifications that I got at the Purser’s Desk in May 2024. I don’t like it. The photo shows how the bridge looked before the bridge wings were extended by six feet a side in 2006! And while the height of the funnel above the waterline is 62 m, that’s 203.4 ft, not 244 ft. I pointed out the errors to the staff; I wonder what the next version I collect will be like.