I know this question cannot be concretely answered but even an educated response would be appreciated. I have a newly acquired Evinrude V4 VRO 90 HP outboard on a 18 ft Wellcraft(I think going by the logo on the seats only, no other markings on the boat), bowrider. Pretty sure the motor is a 1987 model. Model number is J90TLCUR if that helps .My question is, how many gallons per hour can I expect to burn at say almost full speed? Or just cruising around at say half throttle? Like I said I know I can't expect a concrete answer but a ball park figure would help me win an argument with the wife. Thanks in advance.