Gas Mileage

[SimilarIsland]

I'm curious what kind of gas mileage does an older (80's 90's)Mercury 15 hp two stroke get on a 14" aluminum boat?

[boatfixer]

As a general rule of thumb on carburated engines, 10% of the horsepower=gallons per hour at WOT. In your case about 1.5 gallons/hr wide open. Obviously there are other variables but will get you in the ballpark.

[Outfitter17]

Hey Similar,

FYI, we can fish on straw lake all day walleye fishing putting in about 8:30 - 5 and we use about 4 gals in our 16' lunds with 15hp mercs. I know you are familiar with straw, so it gives you some idea how much you would burn in a day.

[SimilarIsland]

Thanks Boatfixer. So does 10 miles per gallon or so sound about right?

Also, what percentage of horsepower would a 90 hp Optimax run at? I figure on an eight mile run I did 5 times in one day, I used 5 gallons. That would put my Mpg at about 8 miles per gallon.

[SimilarIsland]

Hey Outfitter17,

I'm trying to get an idea how close my Outfitter 1750 with a 90 hp Optimax comes to one of the island boats with a 15 hp carbed Mercury. It seems like over a day of fishing, I use about the same amount of gas. Some of that can be attributed to my electric trolling motor.

[boatfixer]

Thanks Boatfixer. So does 10 miles per gallon or so sound about right?

Also, what percentage of horsepower would a 90 hp Optimax run at? I figure on an eight mile run I did 5 times in one day, I used 5 gallons. That would put my Mpg at about 8 miles per gallon.

I'd think it would be similar conversion. Documenting and keeping track of conditions/throttle position etc is the only way of really knowing. I had the opportunity of spending a fair amount of time with one of Mercury's fuel systems engineers and there are so many variables and things to consider but it sounds like you are figureing things out pretty good.