Sorry, A bit missleading on the OPTi and Four stroke figures
A 200Hp carb will use Approximatly 66 litres an hour at wide open throttle.
So a 200hp OPTI will use a third off that figure again. Third of 66 is 22 litres.
Take 22 from 66 gives you 44 litres an hour.
This is only used as a guide so no one start saying how wrong it is
. Always depends on the boat and load in the boat etc etc.
God just read all that, sounds like a maths lesson!!!!