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

Rain City said:
Well the whole claim with the sharrows is that you're not plowing water at those rpms. They provide more lift and thrust at lower rpms, aledgedly.
Click to expand...
I still don't think you some of you guys are understanding this. You can't run these engines at 3000 rpm. No power. Period. Only way to gain GPH is by running at lower rpm. I can see maybe a 5 or so percent in fuel savings from prop to prop. Especially when not propped correctly. Which most boats are not.

Fuel burn equals hp. Period
 
Their big marketing hook is “True Advance” which speaks to zero prop slip. Whether that’s the case or not remains to be seen. I suspect it’s a function of hull design and power to weight ratio on the boat you’re trying to make more efficient. They do seem to significantly reduce cavitation, though, which is the part of hydrodynamics that keep props from moving forward through the water in direct correlation to the pitch of the blades...as in 18.5” pitch = 18.5 ” of forward motion which would be the zero prop slip we all dream about

Yes, you gain GPH by running at a lower RPM but if your prop has less slippage, you might not necessarily be losing speed at that lower RPM
 
Last edited:
Sharphooks said:
Their big marketing hook is “True Advance” which speaks to zero prop slip. Whether that’s the case or not remains to be seen. I suspect it’s a function of hull design and power to weight ratio on the boat you’re trying to make more efficient. They do seem to significantly reduce cavitation, though, which is the part of hydrodynamics that keep props from moving forward through the water in direct correlation to the pitch of the blades...as in 18.5” pitch = 18.5 ” of forward motion which would be the zero prop slip we all dream about

Yes, you gain GPH by running at a lower RPM but if your prop has less slippage, you might not necessarily be losing speed at that lower RPM

That’s the golden chalice when considering marine propulsion and how to make it more hydrodynamically efficient
Click to expand...
I tried 18.5 pitch props, they were unreal in calm water. RPM’s came down at running speed, better fuel efficiency. Problem was when it blew up I was dead in the water. Scary situation, cavitation was so bad I could not get out of the hole. We had to time the back side of a swell to gain speed and get on plane. It took a good amount of time in terrible seas to do so. Once we got up on plane, had to keep speed up at cruising or I’d come off step and start over. Lucky Pursuit’s can bomb through 6 footers at 28 mph. Took a bunch over the hard top. Docked and put the 17 pitches back on. All good since then.
 
Well first off if you can afford a boat of that size and those engines usually moneys not a factor or else you wouldnt buy a 8 tonne boat . Its a boat they LOVE fuel... "BOAT "Bring Out Another Thousand. Dont think there is much you can do to save money on fuel , unless you tie it up at dock like some and sit on it and party zero fuel consumption then ,just lots of other consumption!!!! LOL LOL
 
wolf said:
Well first off if you can afford a boat of that size and those engines usually moneys not a factor or else you wouldnt buy a 8 tonne boat . Its a boat they LOVE fuel... "BOAT "Bring Out Another Thousand. Dont think there is much you can do to save money on fuel , unless you tie it up at dock like some and sit on it and party zero fuel consumption then ,just lots of other consumption!!!! LOL LOL
Click to expand...
It's getting to be more like "BOATT", bring out another ten thousand :cool:
 
Chasing fuel efficiency on big and expensive boats is more about range between fill ups than saving a few bucks. That's why even if a prop is slightly more efficient it doesn't really matter what it costs to folks with deep pockets, and doesn't have to be justified in actual fuel$ savings.

I have been really impressed with enertia ecos, I would see if you could get your hands on a few to try. They make them in 0.5p increments, it would be worth trying a few different pitches.
 
wolf said:
Well first off if you can afford a boat of that size and those engines usually moneys not a factor or else you wouldnt buy a 8 tonne boat . Its a boat they LOVE fuel... "BOAT "Bring Out Another Thousand. Dont think there is much you can do to save money on fuel , unless you tie it up at dock like some and sit on it and party zero fuel consumption then ,just lots of other consumption!!!! LOL LOL
Click to expand...
At the risk of sounding like a tree hugger, it ain’t the out of pocket gas expenses I dwell on....it’s trying not to slobber at the resource trough...

When I bought my first V8 truck to haul a boat and camper, my deal with myself was I’d bike commute as penance which I did for 6 years—-40 km each and every work day through rain, snow, sleet and hail

If I end up bellying up to the bar for a pair of Sharrows, I won’t be doing amortization calculations once they’re bolted on. I’ll just know I’ll be burning less gas for any given amount of navigation I do in that boat.

And yes, added range would be a huge chunk of collateral benefit for the trip I’m planning next summer.

Sounds corny, I know, but someone’s gotta drag that resource extraction cross down main street
 
Last edited:
Sharphooks said:
At the risk of sounding like a tree hugger, it ain’t the out of pocket gas expenses I dwell on....it’s trying not to slobber at the resource trough...

When I bought my first V8 truck to haul a boat and camper, my deal with myself was I’d bike commute as penance which I did for 6 years—-40 km each and every work day through rain, snow, sleet and hail

If I end up bellying up to the bar for a pair of Sharrows, I won’t be doing amortization calculations once they’re bolted on. I’ll just know I’ll be burning less gas for any given amount of navigation I do in that boat.

And yes, added range would be a huge chunk of collateral benefit for the trip I’m planning next summer.

Sounds corny, I know, but someone’s gotta drag that resource extraction cross down main street
Click to expand...
ALL good man just poking a bit tounge and cheek.
when I had a smaller boat and then went to a bigger boat I had a friend up until then when I said it was going to cost " X "amount now instead of "x" amount and this was the same guy that took most of the fish and crab ... we didnt fish after that unfortunate but oh well and they had more then enough money .
unless your on a 18 foot alum or double eagle,hourston etc once you get past that 24 foot mark and over 8000 lbs the boats are gonna DRINK fuel no way getting around it.
 
ship happens said:
I still don't think you some of you guys are understanding this. You can't run these engines at 3000 rpm. No power. Period. Only way to gain GPH is by running at lower rpm. I can see maybe a 5 or so percent in fuel savings from prop to prop. Especially when not propped correctly. Which most boats are not.

Fuel burn equals hp. Period
Click to expand...
Agreed, it's apples to oranges.....the apples, stock props. The oranges, performance props which already have proven gains and we've been utilizing and measuring against stock props for some time. Sharrows can now be put in this category.....it's not rocket science. I'll stick with my 20% gain on the Eco Enertia.
 
BC Coast Pilot said:
Agreed, it's apples to oranges.....the apples, stock props. The oranges, performance props which already have proven gains and we've been utilizing and measuring against stock props for some time. Sharrows can now be put in this category.....it's not rocket science. I'll stick with my 20% gain on the Eco Enertia.
Click to expand...

Yep that's the skinny. Cheers to that
 
BC Coast Pilot said:
Agreed, it's apples to oranges.....the apples, stock props. The oranges, performance props which already have proven gains and we've been utilizing and measuring against stock props for some time. Sharrows can now be put in this category.....it's not rocket science. I'll stick with my 20% gain on the Eco Enertia.
Click to expand...
Hey I was just wondering, what do you think of those Eco Enertias? ;)
 
NOW if someone really used the boat alot i mean alot like 500 hours plus running time per year then it would be something to look into.
Just a normal rec guy then the money spent to money saved just isnt there. GAS is really one of the cheaper things you put into your boat...
 
Rain City said:
Hey I was just wondering, what do you think of those Eco Enertias? ;)
Click to expand...
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🤣
 
You must log in or register to reply here.
Back
Top