Re: ffuel consumption for 3.0 mercruiser i/o marine engine
As Bond-o said! But there are alot of un-answerables in this equation rig size, load on rig, water conditions and efficiency of motor. I know my lil 3.0LX is a fuel mizer I don't really push it and my boating habits aren't consistant by anymeans but I can say this if the tank if full (20 plus gallons) I can definately get 4 to 5 trips out on the lake with it and that includes tubing and buzzing around all day.
Re: ffuel consumption for 3.0 mercruiser i/o marine engine
I have a 3.0 in an 18.5 foot stingray. It will use 4.2 GPH at 3k RPM which puts me at about 27 MPH. That is just with me in the boat. At 3.5k RPM the GPH goes up by 50%.
Just to clarify your question: Fuel consumption is rated in either miles per gallon (MPG) or gallons per hour (GPH) not hours per gallon. Size of the boat, load, wind, current and how you drive all affect economy just like your car. If you have a 40 gallon tank and the engine burns 5 GPH you can run for 8 hours. How far that will carry you depends on whatever speed 5 GPH produces. If you cannot afford $20 per hour operating costs just for fuel, this form of recreation is not for you.
I know this is an old thread but maybe this will help. I ran across this calculator from mercury marine describing fuel consumption at various RPM's.
I have a new to me 19 ft glasply cuddy, 3L V Hull. By using this calculator I can see that when running at 2500 RPM I will consume 3.8 gallons per hour. I found that a sweet spot for me is at 2800 RPM and that puts me at 19 mph - GPS. https://www.boat-fuel-economy.com/mercury-mercruiser-3.0-181-fuel-consumption-liters
Key to me understanding this is thinking of the motor running on a bench test and not in a boat. With an applied load it will burn a determined amount of fuel at a given RPM.
So for me I like to know how far I can go on a tank of gas. By GPSing my speed at RPM, I can divide my MPH by my GPH and know how far I can go and adjust accordingly. Of course these are numbers on paper and actual efficiencies are a matter of you getting to know your boat.
