Gallons Per Mile - Moderated Discussion Areas

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Whaler Performance
  Gallons Per Mile

search | FAQ | profile | register | author help

Author Topic:   Gallons Per Mile

jimh posted 08-05-2006 09:39 AM ET (US)
The rise in fuel prices in North America has set many of us into pondering our outboard motor fuel economy, and some are considering getting a new motor in order to reduce the expense of the fuel it uses. Information about fuel economy is often presented in terms of miles-per-gallon, but using the inverse of that parameter, gallons per mile, may be a better way to see the potential for savings from improved fuel economy.
Based on my recording keeping, my current boat and motor average about 1.85-MPG. Replacing the classic two-stroke engine with a modern fuel-efficient engine should improve the fuel economy about 40-percent, according to the engine makers. This implies a new average fuel economy of about 1.85 X 1.4 = 2.6 MPG. Converting these MPG figures into GPM is simple:
Old engine = 1.85 MPG = 0.54 GPM
New engine = 2.6 MPG = 0.38 GPM
The differential gallons-per-mile is thus
0.54 - 0.38 = 0.16 GPM
My historical data shows I generally do not travel more than 1,000-miles per season. Using this distance, you can easily see how much fuel per season I can expect to save with a new engine:
0.16 gallons/mile X 1,000 miles = 160 gallons
Now all that is needed is an average price for the fuel. I'd say that $3.50/gallon is close. This implies a potential savings of
160-gallons X $3.50/gallon = $480
This tells me that I will not be able to recover the expense ($11,000) of the new motor in fuel savings for a long time, or perhaps I should be using my boat more often!
This same type of analysis may be useful with your vehicles, too. For example, consider moving to a vehicle that gets 40-MPG from one that gets 30-MPG. Initially it sounds impressive. Consider this:
Old vehicle = 30 MPG = 0.033 GPM
New vehicle = 40 MPG = 0.025 GPM
Differential GPM = 0.033 - 0.025 = 0.0083 GPM
If I drive 12,000 miles per year, I will save
12,000 x 0.0083 = 100 gallons
If gasoline is $3.50 per gallon, I am only saving $350 per year with the more fuel efficient vehicle.
The Judge posted 08-05-2006 10:34 AM ET (US)
Not the best comparison Jim. Why on earth would anyone buy a $11k engine to save money on gas? The question should be whether or not to buy a carbed 200 merc for $9k or a Optimax for $11k and how long would it take to recoup the $2k difference. In your case about 4 years but the resale would also be better so it is a no brainer if you have the extra $2k or so. When gas was $1.50 it made less sense because it would take 8 years to match. Plus that $2k at 11% growth would double in 8 years roughly so you might be better off with the carbed engine if the market would fetch you the average it has done over the last 80 years or so :)
Now let's take another scenerio. My 19' has a 40 gal tank. My 1991 Johnson 175 ran excellent but burned 9gph at cruise. leaving me with about 3-4 hours of run time. My 115 Suzuki cost me about $5k after selling the 175. Sure I lost 10mph top speed but at cruise I am the same(25mph). At cruise I now burn 4.5gph which gives me about 8 hours run time per tank.
Again I am saving say 4gph at cruise at $3.50gal which is $14/hr and no oil which is another $4(24ounces)so $18/hr savings. With an average of 100hours/season that is $1800/year which will pay itself off in 3 years and I will STILL have 3 years left on my warranty. So I replace a 15 year old engine for $5k, double my range, save $1800/yr...what do you think about repowering now? Thing is I do about 200 hours a year so I will make it up in less than 2 years. Resale also doubled on my rig with the new power and I am 2006 EPA compliant.
Perry posted 08-05-2006 04:04 PM ET (US)
The extended range (up to 50% more) is what attracts many people here to repowering with a new fuel efficient motor. I don't think it always boils down to recooping your investment with the cost savings in fuel.
The ability to go further out to sea to land the big game fish or travel further to a distant destination is important to me.
swist posted 08-05-2006 07:30 PM ET (US)
I give credit to Jim for doing the arithmetic most people don't bother to do.
But repowering and other such decisions are usually based on a lot of subjective factors even though most people try to convince their wives that every boating expenditure is based on sane monetary logic :-)
It has been proven without question that the most fiscally sound way to own an automobile is to run it into the ground before buying another one, but few people go this route.
As they say, don't try to sway me with common sense and logic!
VI Jamie 22 posted 08-05-2006 10:07 PM ET (US)
I just replaced my engine for a fuel efficient engine. I do not care about the logic of going to a fuel efficient engine. For me, it is all about thinking about how much money I am spending That Day. If I go for a ride and I know it is going to cost me 70 dollars, I might think twice. But, if it will only cost me 40 dollars, I enjoy the ride more. And am more likely to use the boat more. It works for me.
VI Jamie 22 posted 08-05-2006 10:09 PM ET (US)
B
RJG posted 08-05-2006 11:10 PM ET (US)
I have to stand in jimh's corner on this one. We have the same boat and HP. Our performance numbers are very close. I have a Yamaha 225 vs his OMC. Though my Yamaha runs like a champ and gives me no trouble at all, I doubt any outboard dealership, regardless of MFG., would give me much on a trade in. In my case it makes much more sense to run her 'till she dies. I understand the daily expence logic but the reality is one has spent many thousands of $$ to get maybe 1 more MPG.
Perry posted 08-06-2006 02:14 AM ET (US)

quote:
the reality is one has spent many thousands of $$ to get maybe 1 more MPG
I think the reality is that a new 4 stroke or a DFI 2 stroke will get more than 1 MPG increase in fuel economy.
A buddy of mine has an old 140 HP 2 stroke on his Classic 18 Outrage and he gets around 3 MPG cruise but terrible fuel economy at idle. The new 135 HP 4 stroke on my heavier 190 Outrage/Nantucket burns about half the amount of gas at cruise and gets around 5 times better fuel economy at idle speeds.
This is just one example but I think the difference in fuel economy is greater than some think it is.

VI Jamie 22 posted 08-06-2006 04:55 AM ET (US)
I agree with Perry. I sell Etecs and what I consistently hear is that overall, rhe new owners that had a carburated 2-stroke, are getting DOUBLE the fuel mileage. In other words, for the same use, they are using half as much gas. Of course part of this is that their old outboard is older and not as efficient as it was when new.
About the expense of getting a new outboard. Teah, I agree, I ended up with a 2003 Ficht Evinrude. The reports I get from a local boat rental, is that this motor gets the same fuel mileage as an Etec, just does it noisier.
phatwhaler posted 08-06-2006 05:28 PM ET (US)
Here's how I think about fuel economy:
Dollars per Mile
It cost jimh $1.35 for every mile he travels at cruise. ($3.50 / 2.60mpg)
My own personal boat is running about $1.00 per mile since I fill up at the gas station for $2.89.
Thankfully my boat is paid for, sitting on the trailer in the backyard, with $250/year for insurance.
phatwhaler out.
VI Jamie 22 posted 08-06-2006 06:25 PM ET (US)
My 1979 22 OR with a carbed 200 Johnson in excellent running condition got 2 miles to the gallon on average. I drive real conservatively, but rarely on flat water. I am hoping that with the new engine, this will go to 3.5 to 4 miles to the gallon. In your math, oil should be taken into account. This includes oil for 4-strokers. Carbed engines use the most.
towboater posted 08-07-2006 06:39 PM ET (US)
thx for that info Jim,
Im all for itemizing operating costs.
ALL aspects of my Tug expenses are averaged, then itemized on a hourly basis. Then I quadruple it and send a bill...just kidding.
I agree with Perry, size of tank and range is probably more legit issue to consider repowering with fuel efficient engines than just to save gas money alone.
Dont get me wrong, I ENVY anyone who can afford new engines for any reason.
I figure the total cost of my used thirsty engines have a potential to be substantially LESS than buying the most efficient new engines over a 3 year period. Talkin 150 hp twins at the current gas prices & I got pretty good deals. The "potential pill" has some risk I accept.
A alum salt water trailer may also become a cost effective expense if you berth in salt water and are having problems paying Marina fuel prices. Going to a gas station has potential to save .50 - .75 per gal in this area.
Man, the way this mid east crap is shakin out, I may need to start considering a sail boat.
mk
jimh posted 08-08-2006 01:07 AM ET (US)
The use of a gallons-per-mile analysis helps to focus on the critical factor--the miles. Even a spectacular improvement in fuel economy would not have much economic impact if there are not a lot of miles in the equation.
Were I a commercial boater and used my motor a great deal more, the incentive to get a more fuel efficient motor would be much greater. Let's say I am a charter fishing guide and I run 100-miles a day, five days a week, 40-weeks a year. That is 100 x 5 x 40 = 20,000 miles of boating each year.
A differential gallons-per-mile of 0.16 means I will be saving
20,000 X 0.16 = 3,200 gallons each year.
At $3.50-per-gallon that is a savings of $11,200, and thus a new motor pays for itself in the first year.
This is the whole point I am trying to make. It is not the improvement in fuel economy itself which will save you money. It is the combination of how much you use the motor and how much better fuel economy it gets.
After I got back from my most recent trip to Canada where we had to pay about $4.20 a gallon for gasoline, a lot of my colleagues at work wanted to know if it was costing me a fortune to use the boat. My answer was, well, not really, because I did not have to buy that many gallons at that price! I just bought a tank full or two. People pay $200 for a round of golf, so $200 for gasoline for long day on the water is not an outrageous expense, especially if you only do it one or two days a year!
OutrageMan posted 08-08-2006 07:51 AM ET (US)
I would have to say that "The Judge" has the best logic here. In order for this to be an accurate assessment, you have to take a constant like "I am buying a new engine(s)." After that, you can use a cost basis of the most basic engine, and then compute your ROI using the costs of the added options or feature sets. In this particular case, you would use the added cost of a 4 stroke over a standard 2 stroke and then do the math on that cost differential.
Finally, doing a ROI analysis on fuel consumption alone is a red herring. You must also figure in maintenance, insurance, and depreciation costs (among others). Based on that, I am not sure that you would ever not be upside down on any gas powered capital investment.
Brian
RJG posted 08-08-2006 08:34 AM ET (US)
Jimhs numbers assume a cash purchase. Say I don't have $11k cash but I need a motor and I can finance that money. Borrowing $11k at 6.75% for 5 years gives me a monthly payment of $216.52.
$216.52 x 60 gives a total cost of $12,991.20. So my interest carry for the life of the loan is $1,991.20 or about $33.19 a month(10 gallons of Fuel). So a new motor with much improved fuel economy and the peace of mind that goes with it for $216.52 per month. Something to think about.
jimh posted 08-08-2006 12:48 PM ET (US)
A very thorough analysis of the costs of purchasing a new engine was the outcome of a previous discussion on that topic. If you are interested, re-visit:
New Engine: When to Buy
http://continuouswave.com/ubb/Forum1/HTML/010777.html

As an outgrowth of that discussion, a university professor in economics used the problem in his teaching, and he developed a spreadsheet for analysis. This is explained in:
Engine Cost Analysis Spreadsheet
http://continuouswave.com/ubb/Forum1/HTML/010848.html
Buckda posted 08-08-2006 04:33 PM ET (US)
By JimH's calculations, I've switched from .35 GPM to .25 GPM.
I've already travelled over 1,000 miles aboard this year. I figure I'm good for another 500 by year's end.
That represents a 150 Gallon fuel savings on the year, or about $450 at the current $3.00 or so a gallon I'm paying.
Of course, this will slide higher as gas continues to be more expensive.
I sold my old engine for $1,500, minus $50 to have it de-rigged off the boat, and I sold the control separately ($75) and the props ($200 and $75) - for a grand total of 1,800 residual value in the old engine.
Take that from the cost of the new engines, guages, installation, brackets, controls, hydraulic steering, guages and props (about $14,000) and we have a figure of $12,200.
At current use and at $3/gallon, it will take 27 years to recoup the cost of this investment.
Good thing it wasn't a strictly financial decision - and that of course does not take into account the further depreciation of the old motor (minimal) or the depreciation of the new motors (significant at first), nor does it include the cost of repairs.
Finally, and for me the biggest oversight in all calculations available - it fails to consider the value of peace of mind - the values of my own personal motivations for buying new power. That intangible - be it the altruistic end of a less polluting motor or the safety factor or the quiet benefit...whatever it is - is the factor that tips the scales for MOST buyers.
And don't forget to include the silence from the copilot's seat when doing the calculations. When you're wrenching on an old oily, smokey motor in the middle of the Lake, that motor can cause an awful lot of noise from the co-pilot's chair that lasts long after the engine is running again! :)
towboater posted 08-09-2006 02:20 PM ET (US)
well, i sure had a tough time deciding & rest assured, if I could afford it, your numbers prove in most cases new engines are a no brainer.
My situation...needing twins,
the biggest thing was trying to talk myself into putting $30k investment (incl financing) on the back of a GSA $8k somewhat abused hull that might reach $15k restored value without considerations for how much the time & materials cost to get there. I will clean it up, make it presentable & serve my needs but overall, I am going to continue to abuse it.
Im not in this to make money, but, I cant afford to toss it away either.
In 3 years, I MIGHT get $25k high estimate return out of a $30k engine + $10k low end estimated restoration cost
= $40k
= a ballpark $15k loss.
The 3 year difference in fuel/oil saving est should not exceed $6k if I run almost every day all summer.
Whether or not I get tired of filling up .32 times more often to go the same distance will be the issue.
a big issue.
thx jim.
mk

JayR posted 08-10-2006 08:03 AM ET (US)
I used to have an Eastport with a 1988 88 HP Evinrude on the back.
Quick comparison has me getting similar fuel usage in my ribbed Outrage with the 150 HP E-TEC. 6 gallons per hour at 30 mph. At least that's what the I-Command system is telling me....
I did 29.2 miles last weekend on about 9 1/2 gallons of fuel. That's a rough guess looking into the portable tank and guesstimating the remaining fuel.
mfrymier posted 08-11-2006 12:03 AM ET (US)
i'm a bit surprised that more people haven't mentioned environmental impact as one of their reasons for re-powering. We all enjoy being out on the water, be it a lake, ocean, river, bay, etc. The less gas we all put in those bodies of water, the more they will be enjoyed by future generations. I guess i'm a bit of a Northern California (or central californian if you listen to Kriz) liberal, but it was likely THE deciding factor for me.
And MK -- i think you made a great choice in your "work boat" situation. You picked up 3 150 BLACK MAX's for under $8k? Twins and a full set of parts? thats a no brainer....
Jimh -- it's a good analysis nonetheless. I think conservation doesn't really "pay" in many cases, but the fact that we're using less materials has got to be 'good" at some level eh? Leaves more gas for MK!!!!
highanddry posted 08-11-2006 03:55 AM ET (US)
The total cost analysis is valid but I imagine the difference would be greater than 1.0 MPG. I get 30 MPH at 6 GPH with the 150 Opti and at 24 to 26 it drops to 4.5 or so. At 22 to 24 it approaches 6 MPG.
The Judge posted 08-11-2006 11:36 AM ET (US)
2 things...
1)I did mention EPA impact on my post.
2) Jay if you are burning 6gph @ 30mph, then why did you burn 9.5 @ 29.2 miles?
JayR posted 08-12-2006 08:45 AM ET (US)
Good question....
JayR posted 08-12-2006 08:48 AM ET (US)
I suppose running above 5000 rpm's for a considerable time had something to do with it.
I've still less than 10 hours on the motor. Limited exposure to it at this point.
JayR posted 08-12-2006 03:22 PM ET (US)
Gotta stop answering questions before the coffe has started working...
This is why I got only 29 miles with 9 plus gallons of fuel http://img485.imageshack.us/img485/3207/08062006010jb0.jpg
The trip back from the island was with this prop. Duh!!!!
See the end of this thread for more http://continuouswave.com/ubb/Forum4/HTML/004303.html
Heck, I'll save ya the trouble..

quote:
JayR posted 08-06-2006 09:15 PM ET (US) Profile for JayR Send Email to JayR Well.... just as predicted
http://img137.imageshack.us/img137/9366/08062006003ad2.jpg
http://img485.imageshack.us/img485/3207/08062006010jb0.jpg
Thankfully I made it back to the ramp 18 miles away :-) Not even a bit of wobble or shake in the motor despite the prop being smashed.
In the dark, I failed to stay on my GPS track through a boulder field as I was passing between two islands. I was just thinking I should shut it down, lift the motor and drift my way through when I heard a light thump.
I actually thought I hit a lobster buoy. I did not see the damage until it was on the trailer. No marks on the hull or the lower unit. I must have just caught the boulder.
Very happy I opted to stick with the aluminum propeller at this point. I'll get another and possibly have this one repaired for use as a spare.
VI Jamie 22 posted 08-12-2006 07:03 PM ET (US)
JayR, I respect jimh too much not to help him get this posting in its correct forum. It is clear to me and I am sure to everyone else that the prop should not be in this forum , but rather THE MARKETPLACE FORUM. Please correct your oversight immediately.
swist posted 08-13-2006 07:42 AM ET (US)
Someone mentioned including oil in the calculations. A little arithmetic shows this is not a huge deal now that gas is so high. In a 20-stroke with 50:1 oiling, if gas is $3.50 and decent tcw-3 oil is $15/gal, that works out to around 8.5% additional for the oil.
For a 4-stroke, most do not use oil between changes, so assuming 100 hrs between changes, and some modest consumption like 5 gph, and that your engine uses 6 qts at $6/qt, that works out to about 2% additional for the oil.
The 4-stroke numbers are obviously highly dependent on your fuel consumption and hours between changes, but you can easily work them out for your own situation. And the prices in here are just guesses based on prices I have paid.
JayR posted 08-13-2006 08:31 AM ET (US)
VI, what the he77 are you talking about? Nothing for sale here...
I am answering the Judge's question about why I got the gas milage I stated above when I was getting a reading of 6 GPH at 30 MPH.
Where's your head man?
VI Jamie 22 posted 08-13-2006 02:14 PM ET (US)
Jayr, It was a joke, The prop is mangled and useless, hence the joke that it should be in the marketplace forum. Get it??
JayR posted 08-13-2006 05:18 PM ET (US)
Sorry! Over my head.... :-(
JayR posted 08-13-2006 05:18 PM ET (US)
Can't it be repaired????
tan and white posted 08-18-2006 11:12 AM ET (US)
Don't forget to factor in the opportunity cost in Jim's original scenario. The $11,000, if not spent on the motor, could earn at least 3% simple interest, or $330, less federal income tax. There's your extra gas money.

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.