Fuel Burn of Twin Suzuki DF300’s on a 28 Foot Fiberglass Boat

[Rain City]

What can I say, I've done my homework, or should I say a spreadsheet when selecting props.
Tried Mirage plus 2 pitches, REV 4, 2 pitches, Enertia and Eco Enertia 3 pitches in half pitch increments. The Eco Enertia came out on top in economy and cruise but the REV4 had better top end but lost economy at cruise also a slightly better stern lift and holeshot. I keep em around for wakeboarding. So ya the ECO ENERTIA has saved me lotsa dough, I don't trailer, I run it up and down the West Coast. Hell they even have their own lake for testing, so ya I'll stick with ECO ENERTIA. What props do you run? Apparently it's not ECO ENERTIA

Not yet! But I'm sold

 

[wdlfbio]

That’s a very heavy 28’ boat. Just for comparison, my 2007 Grady 282 with twin yamaha F250s got 1.1-1,3 mpg loaded up with 5 of us for tuna days. That’s running 25-28 mph. We would be about 12,000# of boat and all. Best we ever saw just out and about was 1.5 mpg.

My 30’ Wildcat is probably 14-15k pounds loaded up for 6-7 on a tuna day and we get 1.1 - 1.25 mpg at 28-30 mph with twin Zuke 300s. I’m very happy with that.

I’ve never understood the benefit of the gph for measuring efficiency. Which is better burning 20 gph all day or 25 gph all day to get the 100 miles out and back? I need to know the # of hours running that day to really know which is better. If the 20 gph took 4 hours and the 25 gph took 3 hours, then I’m 80 gallons versus 75 gallons and 1 hour less travel time). Too much math. Hahahaha.

Which is better? 1.0 mpg or 1.5 mpg? 1.5, obviously, and I don’t need to do any other math.

 

[Rain City]

Guy with the podded 30 commander was saying that he burned something like 16GPH at 30MPH with the 350 Verados. Which for those who don't like math, is 1.875 MPG. Very similar to what I get on the diesels. I can't remember his name on here but I'd really like to know if that claim remains after a fulll season.

 

[BC Coast Pilot]

That’s a very heavy 28’ boat. Just for comparison, my 2007 Grady 282 with twin yamaha F250s got 1.1-1,3 mpg loaded up with 5 of us for tuna days. That’s running 25-28 mph. We would be about 12,000# of boat and all. Best we ever saw just out and about was 1.5 mpg.

My 30’ Wildcat is probably 14-15k pounds loaded up for 6-7 on a tuna day and we get 1.1 - 1.25 mpg at 28-30 mph with twin Zuke 300s. I’m very happy with that.

I’ve never understood the benefit of the gph for measuring efficiency. Which is better burning 20 gph all day or 25 gph all day to get the 100 miles out and back? I need to know the # of hours running that day to really know which is better. If the 20 gph took 4 hours and the 25 gph took 3 hours, then I’m 80 gallons versus 75 gallons and 1 hour less travel time). Too much math. Hahahaha.

Which is better? 1.0 mpg or 1.5 mpg? 1.5, obviously, and I don’t need to do any other math.

GPH is used because MPG does not account for environmentals and therefore would not be an accurate measurement of performance. Works on the road as its fairly static. I Typically set up my cruise with the flowmeters and tach.

 

[Rain City]

Buddies big cat (12000lbs) with the 350 DP zukes gets 250L per 100KM. Whatever the hell that means. Funny thing is he said his consumption is exactly the same doing 20MPH or 45MPH. So he goes 45 everywhere, there is an advantage to that I guess.

Google says that's .94 MPG

 

[Thunder21]

Guy with the podded 30 commander was saying that he burned something like 16GPH at 30MPH with the 350 Verados. Which for those who don't like math, is 1.875 MPG. Very similar to what I get on the diesels. I can't remember his name on here but I'd really like to know if that claim remains after a fulll season.

I don’t think that is possible.

 

[Rain City]

I don’t think that is possible.

I agree. I figured that was maybe per engine.

 

[gunnerlove]

Half a pound of fuel per HP per hour. Diesel, gas, propane, or JP whatever...

 

[Rain City]

I don’t think that is possible.

Found it...
Post in thread 'Commander 26,30,re-power older boat,newer,diesel....' https://sportfishingbc.com/threads/...er-older-boat-newer-diesel.80539/post-1131764

It's actually pretty hilarious what happens at the end of the thread too @BC Coast Pilot

 

[dradons]

This thread makes me feel poor.

 

[seabeyond]

I don’t think that is possible.

Agree 100%. Maybe for a minute running the rapids with the tide.

 

[ship happens]

70 liters per hour is what.. 18.5 gallons per hour? @3800 rpm. Seems reasonable. Boat must have been empty and light on everything

 

[Rain City]

70 liters per hour is what.. 18.5 gallons per hour? @3800 rpm. Seems reasonable. Boat must have been empty and light on everything

But that's like 1.7 MPG doing 31 MPH. Even empty he's still over 15000 lbs. That's a substantial improvement over Sharphooks, slightly smaller, new boat.

 

[ship happens]

But that's like 1.7 MPG doing 31 MPH. Even empty he's still over 15000 lbs. That's a substantial improvement over Sharphooks, slightly smaller, new boat.

I don't understand mpg in a boat. Let's stick with GPH and RPM and MPH. That way this information is standardized in North America. And is easily transferable from manufactures specifications without having to do the math

I wpuld be pretty impressed to see any 300hp outboard get better than 10 GPH nominally. Usually it winds up being around 11. 3800 rpm is just getting to the max torque mark so it's a great rpm, however it's best to rate things at 4k because your usually between 3800 and 4200

 

[Rain City]

I don't understand mpg in a boat. Let's stick with GPH and RPM and MPH. That way this information is standardized in North America. And is easily transferable from manufactures specifications without having to do the math

I wpuld be pretty impressed to see any 300hp outboard get better than 10 GPH nominally. Usually it winds up being around 11. 3800 rpm is just getting to the max torque mark so it's a great rpm, however it's best to rate things at 4k because your usually between 3800 and 4200

So we agree, this is much better than what he "should" be getting. In ounces per foot, of course.

 

[ship happens]

So we agree, this is much better than what he "should" be getting. In ounces per foot, of course.

Yeah I would say it's not happening nominally on a boat like that. That's a big heavy boat. That should have more prop in the water imo. Those zuki dual props would be my choice if I was going to toss 600hp on the back of a 30 commander.

Come on @Rain City. Let's get that boat over to the shop

 

[Rain City]

Yeah I would say it's not happening nominally on a boat like that. That's a big heavy boat. That should have more prop in the water imo. Those zuki dual props would be my choice if I was going to toss 600hp on the back of a 30 commander.

Come on @Rain City. Let's get that boat over to the shop

Come on stock market, you mean!

 

[Squire]

I don't understand mpg in a boat. Let's stick with GPH and RPM and MPH. That way this information is standardized in North America. And is easily transferable from manufactures specifications without having to do the math

I wpuld be pretty impressed to see any 300hp outboard get better than 10 GPH nominally. Usually it winds up being around 11. 3800 rpm is just getting to the max torque mark so it's a great rpm, however it's best to rate things at 4k because your usually between 3800 and 4200

I find mpg useful when comparing efficiency of fuel burn. I agree with your numbers as they are comparable to mine but I was mistakenly cruising at 3600 rpm and 27 mph to keep my fuel burn down to 9 gph. But when I cruise at 4000 rpm at 33 mph I burn 11 gph and at 3800 rpm I do 30 mph and burn 10 gph.

These are rounded numbers for illustration but very close to actual numbers in good conditions from my Campion 682 with the Yamaha F300 and Powertech OFS4 17P prop. My point is that I burn the same amount of fuel to get from A to B (3 mpg) and I’m only choosing my travel time. I now mostly run at the higher speed in this range. And as a disclaimer, when conditions are snotty and/or if the boated is loaded I get 2.6-2.7 mpg across a significant range of rpm. In other words my ‘sweet spot‘ is pretty wide between 3600 and 4000 rpm.

I would hazard a guess that a lot of boat and power combinations have a range like this.

 

[salmonkiller01]

But that's like 1.7 MPG doing 31 MPH. Even empty he's still over 15000 lbs. That's a substantial improvement over Sharphooks, slightly smaller, new boat.

But he has 100hp more. The Verado outboards were extremely efficient. How about engine height have you checked to ensure you’re at the right height @Sharphooks ?
When running on plane cavitation plates are not buried?

 

[ship happens]

I find mpg useful when comparing efficiency of fuel burn. I agree with your numbers as they are comparable to mine but I was mistakenly cruising at 3600 rpm and 27 mph to keep my fuel burn down to 9 gph. But when I cruise at 4000 rpm at 33 mph I burn 11 gph and at 3800 rpm I do 30 mph and burn 10 gph.

These are rounded numbers for illustration but very close to actual numbers in good conditions from my Campion 682 with the Yamaha F300 and Powertech OFS4 17P prop. My point is that I burn the same amount of fuel to get from A to B (3 mpg) and I’m only choosing my travel time. I now mostly run at the higher speed in this range. And as a disclaimer, when conditions are snotty and/or if the boated is loaded I get 2.6-2.7 mpg across a significant range of rpm. In other words my ‘sweet spot‘ is pretty wide between 3600 and 4000 rpm.

I would hazard a guess that a lot of boat and power combinations have a range like this.

MpG is maybe useful for some however it's not an accurate representation for a marine traveling vessel for several reasons. It's not used and will make things more complicated.

That's really good numbers with a 25ft boat with a single 300. I'd say you'll never do better than that.