best speed for economy

[georgiaboy]

I know every boat is different but there much be some pointers. If I troll at 3 mpg do I get better mileage than when I go 30 mph going back to the dock? My boat seems to like to run at about 3300 rpm at 32 mph.

 

[tashasdaddy]

Re: best speed for economy

what motor?

 

[georgiaboy]

Re: best speed for economy

I have a 2005 Johnson 90 hp on a Triton 176 aluminum bass boat.

 

[mthieme]

Re: best speed for economy

I think you are asking if you get better economy going slow versus going fast.
Yes...at least all my boats do.

 

[erikgreen]

Re: best speed for economy

You'll use less fuel per mile traveled going slow than fast.

For an example, look at boats with displacement hulls. A 35 foot trawler can have a range of 1500 miles with a pair of 100 gallon diesel tanks, where a 35 foot planing hull might get 400 miles out of the same amount of gas. Usually the displacement hull has a much smaller engine, too.

There's some difference in mpg between gas and diesel, but you get the idea.

However, most folks don't want to go places at 10 mph unless they can bring a spare helmsman and take a nap en route.

 

[QC]

Re: best speed for economy

Almost all planing v-hulls do get better economy at displacement speeds. Sometimes as much as double that of the best economy for a speed above displacement (planing). Generally speaking, 16 - 25 foot boats seem to always be best around 30 MPH. As it seems you have found . . .

 

[tashasdaddy]

Re: best speed for economy

most outboards have what use to be called cruise control. go to full throttle, the back to 7/8-3/4, this leaves the spark advanced, and cuts back on fuel usage. you loose 2-5 mph.

 

[wca_tim]

Re: best speed for economy

do some searches and look for some of the threads where user "45auto" (and "qc" and others as well) posted really good information on this and related issues, with graphs, etc... If you're interested, there is some great info on the subject...

 

[Steve Mahler]

Re: best speed for economy

I get about 16mpg at 55 mph with my fishing boat.


on the trailer. LOL


Seriously there are two sweet spots on any boat - low displacement speed, minimal wake or bow wash

And just on plane, enough that you are not still tail dragging. There are a lot of charts out there that show different gph and mpg at various RPMs for different boats.

 

[tashasdaddy]

Re: best speed for economy

also every boat is different. depending on where your load is. if you have a big ole boy, in the stern, or bow makes a big difference.

 

[erikgreen]

Re: best speed for economy

Also where the cooler is, and how much beer is still in it

If you really want to know your fuel economy at various speeds, get a fuel flow meter. They're cheap now, $200 for mine.

 

[45Auto]

Re: best speed for economy

Not your exact boat but pretty close.

http://www.yamaha-motor.com/assets/...tin_2stroke_hpmidport_al_alm-vs170-90tlrc.pdf

This 17' Alumacraft with a 90 HP Yamaha 2-stroke gets it's best economy at 3500 RPM and 27.5 MPH. Your's will be similar. As others have said, only way you'll find the "sweet spot" on your boat is with a flow meter and a GPS speedo.