And the sea state, amount of kit and crew on board etc.
Had a 135 Opti on a 585 Ribtec and used to use 1l per nm which seemed about right.
Now have a 8m Scorpion with a 225 Yamaha (4 stroke) and that uses about 30 - 35l/h cruising at 20 - 25 knts. However if you cruise at 40knts more like 70l/h, the very worst I have seen was 94l/h flat out (47knts ish) on dead flat Solent!
