Pontoon boat fuel economy?

Question

I have a 20ft pontoon boat with a 90hp mercury. I get about 1.5 or 2 miles to the gallon of gas. Is this normal?

Answer 1

Parts of the first answer are wrong - the standard measurement for a propeller is Diameter X Pitch.  The pitch is critical for fuel economy and performance. Most pontoon boats use a lower pitch prop for power as you are not usually trying to get maximum speed. For best performance of a 90hp OB on a 20' pontoon boat, you should probably use a prop recommended for that motor on the lower pitch end of the recommended props. On that boat you will be balancing performance against fuel economy. The numbers that you give sound reasonable for that application.

Answer 2

Ok, the first job is to properly set pitch on the prop for the application. The engine manufacturer will have a recommended WOT operating range in terms of RPMs. Your dealer can help you reprop the boat if you are operating outside of the correct range.

Next, cruising should remain under 80% of WOT. Makes sense if you are constantly running around full blast you are going to burn enormous amounts of gasoline, relative to your fellow pontooners. Your engine will also last a lot longer if you don't constantly keep it wide open.

Next, gas consumption on a boat is expressed as gallons per hour. After the boat is propped correctly and you have established a cruising speed and burn rate you will be able to compare your consumption to similar boats powered the same.

Answer 3

You need to hook a tach up while you are running. Try for 4500- 4800 RPM wide open by changing props. The pitch is stamped on the side between the blades. 11 X 17, 13 X 17, etc... The first number is the pitch of the blade. Higher is faster (less power) and lower RPM, lower is more power but slower top speed and higher RPM. Pontoons are pigs on gas and the only way to get mileage is to go slower. I run mine at 1/3 throttle.

Answer 4

Boat fuel consumption is measured by Gallons Per Hour (GPH) and this fully depends on first and foremost - the speed you are going, and secondly (and less importantly) factors like prop, number of people on boat, etc)

At what speed are you getting 1.5 to 2 miles/gallon?  without that info, your question can not be answered