I would think these numbers are reasonably correct. I find it depends on the sea conditions but with 30s runs at 3 l/h and 40s 4l/h at 2400.
I run 1 engine at 2400 as this seems to be the optimal cost to power
Agree also that 4 20l jerries at 80l will allow for up to a week away so generally I hand fill unless planning a long trip away. If you fill the tanks
(in my case 400l) then you run the risk of the fuel going off over time.