Reasonable Fuel Consumption? 175 hp on a 21 footer

[JoLin]

Near as I can figure over several weeks of use, my consumption at cruise (23-25 mph @ 4000 rpm) is in the neighborhood of 8 gals/hr.

Does this seem about right? Being new to boating I really didn't know what to expect...

 

[haskindm]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

Depends entirely on how you are operating the boat. 8 gallons per hour is very reasonable. Many "go-fast" boats burn 40-50 gallons per hour, and some will burn 100 gallons per hour. If you are crusing, and skiing most of the time 8 gallons/hour is very economical. If you are trolling, that may be high. If that is your consumption at cruise, it is VERY good.

 

[JoLin]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

I'll continue to do the math as I use the boat, but I can say with certainty that it's definitely less than 9 gals/hr. I know how many variables there are, so I was careful to qualify that I'm talking about my normal cruising rpm (4000) and normal load.

I also spent a lot of time getting the right prop and setting up the Smart Tabs. Looks like it's paying off

 

[steelespike]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

Yes thats a good gph.Only thing I would add is the best cruise mileage could be from just on plane up to about 2,000 rpm higher.Only careful experimentation or a flow meter can tell exactly.Rule of thumb is wot gph is about 10% of the hp in your case about 17.5 gph.

 

[JoLin]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

Hi, Steelespike,

Yeah, I hear ya in terms of experimentation, and maybe better results at different speeds, but everything just feels "right" at 4000 rpm. The motor sounds happy, the boat rides and handles well, and we cover distance at a pretty good clip.

If I can assume I'm getting decent (comparatively speaking ) mileage at that speed, I'm pretty happy.

 

[CatTwentyTwo]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

I installed a Flo-Scan earlier this year on my 20' Grady with a 94 175 Johnson. I have not had a chance to calibrate it yet, but it reads between 10 and 11 GPH at 3800 RPM.

 

[dingbat]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

Near as I can figure over several weeks of use, my consumption at cruise (23-25 mph @ 4000 rpm) is in the neighborhood of 8 gals/hr.

Does this seem about right? Being new to boating I really didn't know what to expect...

Sounds a little low to me but then again I drive a 22' tank.

At cruise (30 mph @ 4400 rpm) I'm burning right around 13-14 gallons per hour.

 

[JoLin]

Re: Reasonable Fuel Consumption? 175 hp on a 21 footer

Hmmm.... my figure does seem a bit low, doesn't it?

I have a couple of heavy boat use weekends coming up (I hope), so I'm going to start over and see what happens. Right now I have about 45 gallons aboard. I'll repost if things turn out differently.

ryoung, I'd be curious to know what happens after you calibrate your flo-scan. You and I oughta be similar. I'd love to get one of those things, just can't afford one right now.