fuel economy help

[Clutzmi]

im new at boating and we have a 20ft pontoon being pushed by a 90hp evinrude in the Mississippi river. all we do with the boat is cruise up and river and rarely pull a tube. in 20 mins of travel up river i burn 10 gallons of fuel. basically im driving from station to station all day. im wanting to better this what can i do?

we have talked about...

- a new prop (but i have no idea where to start i don't want to spend a fortune trying different pitches and such)

- adding a hydro foil (the fin that bolts over the lower unit)

- motor height (does it make that big of a difference)

- and getting up on plane ( i was under the impression this wasn't possible on a pontoon)


any and all help will be greatly appreciated
thanks in advance

 

[The Rooster]

Re: fuel economy help

Could use a bit more info. I'm assuming it's an older 90 hp, "carb" v4. What rpm's are you running at WOT? I believe you should be in the 5500 rpm range, so you need to prop for that. What size prop are you currently running? By and large, hydrofoils don't work nearly as well as they do on flat or v-bottom boats. Motor height could play a big role in performance, especially if you're too low and dragging the lower unit through the water. I'd suspect the steering to be quite difficult if that was the case. Pontoon boats don't plane like other boats or triple tube barges. They're basically two displacement hulls being pushed through the water. Something is definitely not right w/ the setup if you're burning 10 gal for 20 mins. of cruising. Good luck !!!

 

[MH Hawker]

Re: fuel economy help

yea thats a bit excessive, my old 85 hp V 4 Johnson was around 6 gph that would make you around 30 gph

 

[The Woo Woo Kid]

Re: fuel economy help

Wow. that is excessive. What diameter are your toons ? Are they skinny and you're sitting low in the water ? How old is your motor ?

Maybe something is wrong with your motor, like maybe it needs a tune up.

Any fuel sheen on the water from the exhaust ? What speed or rpms are you running at when consuming fuel at that high rate ? Is the river rough....waves etc ?

From what I've seen, one of the most effective fixes for achieving a faster," better planning", better mileage. improved handling on a toon hull is the Waterglide. they're around $2000. Guys seem to like them and claim they do what they advertise. If the water is choppy underskinning also helps.

10 gallons in 20 minutes is crazy. There's something wrong there.

 

[Old Screwball]

Re: fuel economy help

How bad is the current where you run?? We play mostly on the Colorado River and the current runs 5 to 7 mph. My 'toon will hit 26mph going downstream, but only 12 to 14 going up. (GPS) In the afternoon the current is much less, they slow flow from the dams that really slows down the current.

I remember my old Force 125 (2 stroke) ran over 7 gallons an hour skiing, but you are way beyond that.

 

[Silver Eagle]

Re: fuel economy help

Are you fighting a tide? I travel on the Chesapecke Bay The tide is always a factor. It's easier to go with the flow, both ways.

 

[gpfishingdude]

Re: fuel economy help

I am going out tomorrow and it will be the first time since I installed the tach. I underskinned it this year and fixed the motor where it is firing on all four cylinders, it had a bad coil. It will probably be fall before I get on big enough lake to see if my gas mileage is improved. But I figure it should have. I'm running a 50 horse merc. on a 18' bass buggy.