BEST FUEL EFFICENCY

[JRoberts]

20220924_122941.jpg

Just bought a 2005 36M with Crusader 5.7 gas engines. Wondering if anyone knows the best speed and/or RPMs for best milage?

[buster53]

If you want extended range, keep it to hull speed or less, probably around 7-7.5 knots. As you increase speed above hull speed, MPG’s start dropping. About the worst you can run short of wide open is midway between hull speed and a decent plane… in the 12-16 knot range. At that speed you are wasting a lot of fuel and kicking up a big wake, which won’t make you any friends.

[JRoberts]

Great, thank you. I noticed I can go up to about 10 mph without really creating much of a wake but above that I put up a pretty nasty wake

[Midnightsun]

Your wake is your indicator of how efficiently you are moving the boat, the bigger the wake the less efficient. Up on plane there are really no miracles to be had. My experience with gas engines is they like to be around 3500 rpm with tabs adjusted for best form on the water which usually yields your best efficiency while on plane which is horrible compared to little wake hull speed by the way.

[Cooler]

Each vessel is a little different, depending on several factors, both mechanical and geographical. Best thing to do is test at different ranges. My 5.7XL's burn 15 GPH at 3100 RPM, 19 MPH on the bay of Green Bay. At 3400RPM, that increases to 24 GPH and gains me just 22 MPH. Here is a fun fact. Just 18 miles away, at a marina in Door County, boat bottoms get dirty pretty quick. There are a lot of power boats in that marina, so the water gets an oily film, which attaches to the bottoms, and attracts a lot of gunk. The fouled bottom condition will impact fuel efficiency in a big way. Make sure you have good quality bottom paint and keep that bottom clean. er