Better performance/fuel economy

[mlaymance]

I was wondering what modifications other readers have done to engine/system to increase performance and fuel economy.

EFI, electronic ign., different carbs, etc.....

with the price of gas we can use all the help we can get

Thanks,
Michael

 

[QC]

Re: Better performance/fuel economy

You will rarely, if ever, make a truly economic case for mods that are intended to improve efficiency. Say you spent $1000 to gain 5% (big improvement), let's also say that you run 100 hours a year (a lot for a pleasure boat) and that you average around 10 GPH. This means that you burn 1000 gallons per year (huge number). If you save 5%, it will take you 4 years to get your $1000 back and that's if you burn that much fuel (you probably don't) . . . If your goal was only fuel economy you would save a lot more by knowing the most efficient RPM, speed, trim etc. A fuel flow meter at $281 may be the best way to actually confirm that and it might make a huge difference if you are running in an inefficient manner now.

 

[tysonnathan]

Re: Better performance/fuel economy

most effective and cheapest mod is the way you drive.... knock a little off the cruising speed, dont hoss the boat around, etc. $4 gas has changed the way i drive and it has made a big difference...

 

[Bondo]

Re: Better performance/fuel economy

You will rarely, if ever, make a truly economic case for mods that are intended to improve efficiency. Say you spent $1000 to gain 5% (big improvement), let's also say that you run 100 hours a year (a lot for a pleasure boat) and that you average around 10 GPH. This means that you burn 1000 gallons per year (huge number). If you save 5%, it will take you 4 years to get your $1000 back and that's if you burn that much fuel (you probably don't) . . . If your goal was only fuel economy you would save a lot more by knowing the most efficient RPM, speed, trim etc. A fuel flow meter at $281 may be the best way to actually confirm that and it might make a huge difference if you are running in an inefficient manner now.

Ayuh,....

I Agree Completely,....

Another alternative is to Sell the boat,+ buy a Canoe......

 

[paulrfrancisco]

Re: Better performance/fuel economy

Also you could remove any unnecessary weight from the boat, make sure he bilge is dry...if the boat is old, sometimes the styrofoam gets waterlogged, although not too much you can do about that...

 

[Mischief Managed]

Re: Better performance/fuel economy

most effective and cheapest mod is the way you drive.... knock a little off the cruising speed, dont hoss the boat around, etc. $4 gas has changed the way i drive and it has made a big difference...

Not always true. I put a Lowrance LMF 200 with a flow sender and speed sender in my boat this year and found that 25 MPH gave me worse MPG than 32 MPH (2.3 MPG vs 2.6) I can get all the way to 40 MPH before I drop below the MPG I get at 25.

Removing weight always helps. I can gain .1 MPG just by running with half a tank of gas instead of a full tank. Does not sound like much, but it's a 4% improvement.

 

[bruceb58]

Re: Better performance/fuel economy

Not always true. I put a Lowrance LMF 200 with a flow sender and speed sender in my boat this year and found that 25 MPH gave me worse MPG than 32 MPH (2.3 MPG vs 2.6) I can get all the way to 40 MPH before I drop below the MPG I get at 25.

I notice the exact same scenario. My boat needs to be running over 30 MPH to get its best economy. I have a 7.4L in a 24' boat.

 

[Mischief Managed]

Re: Better performance/fuel economy

I notice the exact same scenario. My boat needs to be running over 30 MPH to get its best economy. I have a 7.4L in a 24' boat.

Funny, I have a 7.4 in a 25' boat...

 

[tysonnathan]

Re: Better performance/fuel economy

Not always true. I put a Lowrance LMF 200 with a flow sender and speed sender in my boat this year and found that 25 MPH gave me worse MPG than 32 MPH (2.3 MPG vs 2.6) I can get all the way to 40 MPH before I drop below the MPG I get at 25.

Removing weight always helps. I can gain .1 MPG just by running with half a tank of gas instead of a full tank. Does not sound like much, but it's a 4% improvement.

Guess it just depends on the setup you have... I have a 20' Bowrider with a 5.0 mercruiser and I have seen big mpg gains from cruising at 26 rather than 33... But, I dont have a flow meter to confirm that this is actually where my gains are coming from. I have also changed the way I drive in other ways which may be causing the improvement in fuel economy... Good point mischief...

 

[wca_tim]

Re: Better performance/fuel economy

My experience on engine mods, etc.... is that it doesn't necessarily make that much difference. Some of the posts from 45auto a while back also indicated that it has a lot more to do with the hull than the actiual engine configuration (assuming not grossly underpowered). Note this is assuming you keep the engine in tune and so forth...

I would have to say that the biggest thing is a fuel flow rate monitor - without knowing where the "sweet spots" are in miles per gallon (getting there using the least gas) and gallons per hour modifying driving is shooting in the dark...

 

[Kev144]

Re: Better performance/fuel economy

If you complain about fuel prices, it may be time to get out of boating or at least downsize. Boating is becoming a richer and richer mans sport every year. Running some of the boats we do at the marina is about 500+ bucks a day on fuel. But were talking performance stuff. Boats running 125+mph. We see this day in and day out and realistically if you are having problems affording it, either cut back or it may be time to get out.

 

[tysonnathan]

Re: Better performance/fuel economy

If you complain about fuel prices, it may be time to get out of boating or at least downsize. Boating is becoming a richer and richer mans sport every year. Running some of the boats we do at the marina is about 500+ bucks a day on fuel. But were talking performance stuff. Boats running 125+mph. We see this day in and day out and realistically if you are having problems affording it, either cut back or it may be time to get out.

It does cost a heap... a lot of my buddys used to have offshore fishing boats. most of them have sold them or they just leave them sitting. when your running two or three engines for hours to get out to where the fish are, its easy to spend well over $1000 on gas for a saturday fishing trip. then youve got ice, food, bait....
the cost of the boat used to be the big investment... now it is the operation costs that kick you in the wallet....
anyway... i am fishing a lot less than a few years ago...and that is no bueno..

 

[Kev144]

Re: Better performance/fuel economy

It does cost a heap... a lot of my buddys used to have offshore fishing boats. most of them have sold them or they just leave them sitting. when your running two or three engines for hours to get out to where the fish are, its easy to spend well over $1000 on gas for a saturday fishing trip. then youve got ice, food, bait....
the cost of the boat used to be the big investment... now it is the operation costs that kick you in the wallet....
anyway... i am fishing a lot less than a few years ago...and that is no bueno..

You got er. It's becoming harder and harder for the average joe to afford the fuel costs. Your correct though, one of our customers has a boat with triple 1075 CI motors. Fuel cost is massive on this boat. A full day of running yeilds about 1500 -2000 a day on high octane fuel for the beast.

 

[Mischief Managed]

Re: Better performance/fuel economy

Typical day on the water for me means 20-35 gallons of gas. Not a terribly large expenditure, especially when you consider 4 to 10 people will be having a wonderful day on my boat. The current gas prices have just made me more particular about the days I use my boat. I'm much less likely to venture out on marginal weather days now.

 

[tysonnathan]

Re: Better performance/fuel economy

Typical day on the water for me means 20-35 gallons of gas. Not a terribly large expenditure, especially when you consider 4 to 10 people will be having a wonderful day on my boat. The current gas prices have just made me more particular about the days I use my boat. I'm much less likely to venture out on marginal weather days now.

good point... pleasure boating, skiing, inshore fishing and the like are still viable for me... I have no problem laying down 100 bucks on a saturday boating trip. and my buddies usually throw in 10 or twenty a piece. i still think this kind of boating is worth it... its the 1 or 2 grand price tag on a trip to the gulf stream thats no longer doable.
its sad... i no people who worked and saved their whole live to buy that fishing boat they always wanted... then, 6 or 7 years later gas prices have quadrupled and they cant afford to use it.
here in GA the mom and pop commercial fishers and shrimpers are hurting too.. lots are going out of business...

 

[45Auto]

Re: Better performance/fuel economy

I'm on the same page as QC, Bondo, and WCA_Tim here. If you're running a 4-stroke engine (inboard or outboard) in a decent state of tune you'd probably be hard-pressed to increase the efficiency of your engine enough to be able to see it. Takes a given amount of power to drive a hull through the water at a given speed, you've got to burn enough fuel to make that power. Not much room left for improvement in modern computer controlled engines. I think the hull size, design, and loading make a bigger difference than anything you can do with the motor. If you want a certain size boat you're gonna have to pay the price.

Only way to make a big difference is to optimize your boating habits. Take some friends and split the cost. Cruise at max efficiency if you need to run at cruise speed, but if you're just out on the water enjoying the sights let the boat drift or idle around. You obviously won't travel as far, but your fuel cost per hour will go way down! My boat uses 1.8 GPH idling at 5 MPH, about 7.5 GPH running at best efficiency (27 MPH).

Go to Boattest.com (free membership, just need an email address) and you can compare the mileage of different boats. Their tests are very accurate from what I've seen. Their data is also very easy to cut-and-paste to make charts!

Last boat I bought is a 22' bowrider, so I researched what they would do with different engines before I bought mine. The chart below is of 22' boats with I/O engines ranging from 5.0 to 8.1 liter, and a 4-stroke and 2-stroke outboard.

From what I saw a 22' boat with a 4-stroke engine is going to get right around 3.5 MPG at best cruise. As you can see from the chart, the maximum power the motor makes is pretty irrelevent to it's cruise MPG.

The Boattest numbers agree with what I see on my boat. I found my optimim cruise speed to be at 27 MPH and 2300 RPM. The pic below shows the instantaneous MPG of 3.6 MPG (left digital number on the GPS speedo).

 

[abe321]

Re: Better performance/fuel economy

good point... pleasure boating, skiing, inshore fishing and the like are still viable for me... I have no problem laying down 100 bucks on a saturday boating trip. and my buddies usually throw in 10 or twenty a piece. i still think this kind of boating is worth it... its the 1 or 2 grand price tag on a trip to the gulf stream thats no longer doable.
its sad... i no people who worked and saved their whole live to buy that fishing boat they always wanted... then, 6 or 7 years later gas prices have quadrupled and they cant afford to use it.
here in GA the mom and pop commercial fishers and shrimpers are hurting too.. lots are going out of business...

You guys are lucky i guess with the price if gas. Try living in the UK. petrol is near ?1.20($2.40) a LITRE, more for diesel. and we hardly ever get any hot summers