range for a 170 and yama 115

[aviator8]

I haven't had my boat long enough to work out a rough estimate of mileage for my setup.  I know there are alot of factors that play into mileage ie, prop, motor condition, boat, seas, how much power is applied, weight.  Can anyone with a similar setup 1976 170 with a 115hp motor give me a rough estimate on what kind of range i can expect to get with my 27 gal fuel tank?

Thanks
Scott

[LilRichard]

Don't have that setup, but would guess you're in the 3mpg + range at cruising speed.

[Miguel]

My 170 (1985 model) with a mariner 115 cruises at 30mph, burning about 6.5 - 7 gal/hr.  Therefore about 4mpg+.  That is good for a bit more that 100 miles.  Now, factor in that some time is not spent cruising and that you should always keep a safety margin in gas, shoot for about 80 miles to be safe.  In longer cruises, I carry an extra 16 gallons in a portable tank.
I have recently re-propped with a 21 inch pitch SS prop and my top end has gone up from 39 to 42mph per GPS, and cruising has increased slightly to close to 31mph.

[RickK]

I agree, I was going to say 6 gal/hr.

[RickK]

My 170 (1985 model) with a mariner 115 cruises at 30mph, burning about 6.5 - 7 gal/hr.  Therefore about 4mpg+.  That is good for a bit more that 100 miles.  Now, factor in that some time is not spent cruising and that you should always keep a safety margin in gas, shoot for about 80 miles to be safe.  In longer cruises, I carry an extra 16 gallons in a portable tank.
I have recently re-propped with a 21 inch pitch SS prop and my top end has gone up from 39 to 42mph per GPS, and cruising has increased slightly to close to 31mph.

So you broke the 40 mark     I think I got to 40.1 or something close to that once.......maybe it was 39.9     That's it for my boat - now maybe I need to think about the prop......

[Miguel]

So you broke the 40 mark  I think I got to 40.1 or something close to that once.......maybe it was 39.9  That's it for my boat - now maybe I need to think about the prop......

My 170 (1985 model) with a mariner 115 cruises at 30mph, burning about 6.5 - 7 gal/hr. Therefore about 4mpg+. That is good for a bit more that 100 miles. Now, factor in that some time is not spent cruising and that you should always keep a safety margin in gas, shoot for about 80 miles to be safe. In longer cruises, I carry an extra 16 gallons in a portable tank.
I have recently re-propped with a 21 inch pitch SS prop and my top end has gone up from 39 to 42mph per GPS, and cruising has increased slightly to close to 31mph.

So you broke the 40 mark I think I got to 40.1 or something close to that once.......maybe it was 39.9 That's it for my boat - now maybe I need to think about the prop......

Yeap... I broke the mark.  I think I was going with the wind and the current on that run, but hey, it all counts!
With the 19 inch aluminum prop I was doing 5500RPM, which is about 250 RPM too fast for my motor.  A 2 inch pitch increase and change to SS made the difference and lower my WOT RPM to 5200.

[jsakat1]

I have a 130 Yama on my 17 and I get about 2.5 to 3 mpg.  I burned 5.5 gal on a 14 to 16 mile trip last time around.

[thill]

I have an 85 force on mine, they are typically pretty poor on fuel economy...  I average about 3.5 miles per gallon.  If I stepped up to a 75 EFI yamaha, I'm guessing that would go up to about 4.5.

Just something to compare yours to.  Mine gets to about 38 at WOT, but I need to play around with the props, as it feels like it's got more in reserve.

-TH