I'm with Wavelength on this one- tanks you can see/dip
I've looked at different boats and worked with a 20/25 litre portable can so I can work the basic logistics easier than with big inbuilt tanks.
100 on a destroyer 5.8;
I'm currently working on £1 per mile,
between 1-1.5 mile/litre, although, in planning, I'm working on 1 l/m and carrying a bit of spare.
inbuilt gauges/ angles of tanks all too variable, imagine being on a boat where you can't actually access over 100 litre of fuel ( a third of the tank! ) - or another where the gauge states quarter (40litres! ) of a tank remaining, and it stops- new boat/ gauges, and busy working it out and carrying spare fuel