Fuel Usage

I know there have been several threads on fuel usage, GPH, MPG, etc. but I thought my recent info might be helpful to someone. I know that when I was looking for a boat to do the loop, fuel was a critical issue.

The boat is a 1978 Marine Trader 36' double cabin with a recently rebuilt Ford Lehman 120 engine. The bottom was pressure washed last may and divers have kept it in pretty good shape since then.

I filled at Hoppies on the Mississippi in September. Since then I have put on 293 hours and have used 724 glallons of Diesel. That works out to 2.47 GPH.

Speed varied depending on who I was traveling with but on average it was about 7 knots or in my world about 8.4 MPH (at 1,650 RPM).

This included down rivers, up rivers, a Gulf Crossing and down the ICW to Ft. Myers Beach where I just paid $3.81 a gallon.

All of this feels about right for the full 5,800 miles or so that I have traveled since last May but some of my detail was lost to the computer gods a while back so I don't have the data without a lot of reconstructing.

These old Trawlers can be great, comfortable, and economical traveling machines.

Arch

Hi Arch,

With all due respect, fuel usage in recreational power boating such as discussed on this forum ad-nasuem (sp?) DOESN'T MATTER. If you have sufficient fuel aboard to reach your next fuel stop, THAT'S ALL THAT COUNTS. All other issues, particularly related to cost, are lost in the noise for the vast majority of us. If one needs to be concerned with the cost of fuel during your time on the water, you're in the wrong hobby. Fixed costs (depreciation, moorage, insurance, taxes, etc.), and other variable costs of boat ownership (maintenance, repairs, upgrades, etc.) absolutely SWAMP fuel issues.

This is, of course, simply my opinion. However, it's backed by many, many years underway, and many, many miles under the keel of many different boats, both power and sail. I have kept meticulous track of all money out the door related to my boating experiences. The total dollars spent in boating absolutely makes my knees buckle, but given the return, I absolutely don't regret a penny spent. (Well, perhaps the $$ spent repairing my occasional dumb-ass mistakes, but that's another story!) I hope your trip on "the loop" is as much fun as advertised by others, and enjoy!

Regards,

Pete

36 ft boat with a waterline of about 34

Square root of 34 is 5.83095189. X 1.34 = 7.81 Knts per hour.

A 120 ford lehman is governed at 2500 rpm"s.

If in a perfect world you could reach that RPM at WOT. Your boat and prop would be set up for optimal fuel burn.

If you run at about 75 to 80% of the wide open throttle 17500 to 18500 would be the best load for the engine.
That being said I agree totaly with your ending comment.
Fuel burn never was the biggest expense on a boat. Just the most out of pocket at one time.

SD

Well guys, the cost of fuel on a 6,000 mile plus trip in a year is significant in my world. It played a large part in boat selection and in determining if I could afford this trip at all. I got a lot of helpful information from this forum while I was in the early stages of planning the trip, buying and outfitting the boat. This was an attempt to pay back a bit.

Having said that, I can see where this type of information is of far less value to the folks on this forum. I will keep this kind of cost information on the Great Loop Forum in the future.

Thanks for your feedback as I learn what is relevant to this forum.

Arch

It is all revelant. We all use our boats for different reasons.

Everyone talks about how much fuel we burn and cost of same.

Keeping water moving under the keel is what it is all about.

A few dock queens may disagree.

We are all on board one way or another.

It's only money.

Sd

Arch,

An expense in boating is alway significant, be it fuel, moorage, insurance, maintenance, etc. And the further we get along in terms of the cost of fuel going up, the more significant and more discussions you will see. Of course, there are other costs to boat ownership that usually out way fuel cost, but that doesn't make it insignificant.

I have a 600 gal fuel tank that is about half empty right now, and the common opinion for winter storage is to keep that tank full. Well that is 300 gal x $4/gal= $1,200 expense that I'm not excited about adding to the other expenses.

Maybe we could start a TF fuel kitty we all put into for cruising. Say, everyone throws in $50/ month?

Hmmm, maybe that would work. I could cancel one of my Internet services and come up with that

Arch,

Thanks for the information, it is useful to many of us. Please keep posting. To those who don't find it useful, great, but why do you need to denigrate another's opinion? Sheesh!

Bob Cofer said:

Arch,

Thanks for the information, it is useful to many of us. Please keep posting. To those who don't find it useful, great, but why do you need to denigrate another's opinion? Sheesh!

Click to expand...

Agree Bob. Some people just like to hear themselves talk or in this case, read there own words.

Keep posting Arch!

Arch said:

Well guys, the cost of fuel on a 6,000 mile plus trip in a year is significant in my world. It played a large part in boat selection and in determining if I could afford this trip at all. I got a lot of helpful information from this forum while I was in the early stages of planning the trip, buying and outfitting the boat. This was an attempt to pay back a bit.

Having said that, I can see where this type of information is of far less value to the folks on this forum. I will keep this kind of cost information on the Great Loop Forum in the future.

Thanks for your feedback as I learn what is relevant to this forum.

Arch

Click to expand...

Agree that fuel cost impact some of us...those that don't care fine...but only part of the boating world.

For those that run the miles...the costs can become significant enough to watch...be the highest bill of the year...no but that doesn't mean some of us can't use that extra $1000 or so in savings for other things.

I throttle back even further than you and get about 1.9gph burned and 6.3 knots average speed for about 3.3 NMPG. If I'm really not in a hurry and maybe have a fair current much of the day...I'll throttle back even more to make up for the times I push harder to make a bridge or fight a foul current.

Last year my trip worked out to be about $1.00 per Nautical Mile...I kinda like that mentality as it is easy to estimate the budget how far I'm going to go that year.

I agree that if you can't afford the fuel you should not be in recreational boating, but there's little point in wasting fuel.

For me, that means cruising at near hull speed when possible. For us, the trip is as important or more important than the destination so watching the world go by is part of the enjoyment. When I say hull speed, that's speed over water so at a constant RPM, the speed over ground varies depending on the current.

If there's a weather issue or we need to be at a marina before closing time, I'll kick it up a bit.

If you can't afford the fuel..you tie up till you can or don't go as far or as fast as you would like...you just don't sell the boat.

So if going really slow meets the fuel saver cruiser's need and makes the "trip" more enjoyable for those...I don't see the point?

I'm not rich by any standard, my boat cost me $6K plus another 1K in upgrades, my insurance is free as part of my house policy, the marina is $1200 for the season, and getting under 2 gph at cruising speed is the only thing that allows me to go boating (away from the dock!) whenever I wish. I have learned in my limited experience that two things keep those thousands of twin-engine dock queens tied to the dock: fear of handling the boat and fuel cost.

Some people live in a different world than mine, where fuel cost does make a difference. A couple years ago I went out on a sportfish boat with twin 12V71 turbo egnines. The fuel useage on plane worked out to about 4 gallons per mile. At $4.00 per gallon that is $16.00 per mile. My little boat runs close to Arch's, very close, which comes out about $1.00 per mile. My wife and I just finished a trip of about 1000 miles. The fuel cost difference does affect my world.

Arch,
Everybody's scope on this is different.
I think your numbers are good, honest and useful.
We burn 1gph so it's not an issue and Pete burns probably 10gph (or so) but as he pointed out it's not (by a long shot) a big cost considering all the other costs. Our moorage in Alaska was $570 a year. Now in western Washington it's $268 a month plus more for electric. At a gallon an hour I'd be hard pressed to burn more than my moorage. Pete is right though that for most of us fuel is only a small cost.

But you know how far you will be going so you can fairly accurately predict what that cost will be. And that's planing and planing is a big important part of navigation and boating in general. Planing is good and if I hadn't married a planer I could be lost. I actually got lost w her on board and years ago I got lost in Glacier Bay w three women on board constantly turning my chart up side down. The girls all flew home from Gustavus and I was left to find my way home. And I was pleased about that.

I really enjoy posts like this that tell me how much fuel a particular boat has used. What is less important to me is miles travelled, gallons per hour and totall fuel purchased. MPG is king, period. In Statute miles, which we all understand. And I do agree, if you are stuck to the dock you may be a little peeved at those actually burning fuel, well, suks bein you.

kulas44 said:

I really enjoy posts like this that tell me how much fuel a particular boat has used. What is less important to me is miles travelled, gallons per hour and totall fuel purchased. MPG is king, period. In Statute miles, which we all understand. And I do agree, if you are stuck to the dock you may be a little peeved at those actually burning fuel, well, suks bein you.

Click to expand...

Not positive you are looking at it quite right yet....

In reality...only thousands of miles under your keel actually give you the real sense of cruising....waiting for bridges, locks, dockmasters, etc...all eat into your miles per gallon...I only think in Nautical miles per gallon...everyday it pisses me off some NON-BOATER came up with statute miles for the ICW...but that's me.....

Plus I can't be bothered after awhile separating out what my diesel heater and generator uses..so I say..."who cares"...because as I travel it does average out..obviously a little less if I travel in warmer weather or anchor out less...but then my marina costs go up.

So after a trip and some...that lasts thousands of miles and many months...you can pretty much narrow down what cruising costs, time, distances possible, etc...etc will be.

In my current state of work/play where I get the 4 months of winter off from my job...my budget for EVERYTHING..is $1000 per week for the 4 months...as long as that happens I'm good. As I get more time off...my money will go down and my time cruising will go up so at some point my budget might be closer to $500 per week. That means going slower (hard to imagine), less marinas and dinners out, etc....

Actually my financial planning may keep the budget close to the same...but it is possible to really play with the numbers once you have a trip up/down the ICW once or twice....

So to be fair...and annual fuel burn and miles traveled may well be a much better indicator for your future than miles per gallon, gallons per hour or anything else...

Uh wrong, MPG taken when actually moving in a given boat of a given size is the only factor that can tell me or anyone else looking at different boats an idea of what to look for. I do understand current and wind, and at 8 mph they can make a huge difference. So, lets go with SOG@MPG most can understand that. I've been retired 15 years, since I was 38, and have travelled a lot of miles in boats. My biggest expense is fuel, by far. But, I do everything on my boats and I am a frugal shopper. And I dont mind getting greasy. I do understand that if you have just so much time, dont worry about the cost.

What is wrong with statute MPG? The 1000 mile trip I finished last month was marked entirely in statute miles on rivers and the GIWW. If I were on the high seas I woiuld change to nautical miles, but when in Rome.

kulas44 said:

Uh wrong, MPG taken when actually moving in a given boat of a given size is the only factor that can tell me or anyone else looking at different boats an idea of what to look for. I do understand current and wind, and at 8 mph they can make a huge difference. So, lets go with SOG@MPG most can understand that. I've been retired 15 years, since I was 38, and have travelled a lot of miles in boats. My biggest expense is fuel, by far. But, I do everything on my boats and I am a frugal shopper. And I dont mind getting greasy. I do understand that if you have just so much time, dont worry about the cost.

Click to expand...

MPG is the most variable of any indicator we normally discuss.....so as I said...it's only really accurate if the reporter is accurate over thousands of miles/hours..whatever.

Sure...MPG, gallons per hr and speed in still water and air (a true rarity) are all intertwined...but to say one is a better indicator than another....well...whatever....but it leaves out that identical boats could still have subtle differences like flybridge enclosure, different trim based on captain loading...etc...so many things that only averages are truly accurate..none of the instantaneous readings really mean a thing for long distance cruising.

bikeandboat said:

What is wrong with statute MPG? The 1000 mile trip I finished last month was marked entirely in statute miles on rivers and the GIWW. If I were on the high seas I woiuld change to nautical miles, but when in Rome.

Click to expand...

Nothing...just after over hundreds of thousands and possibly millions of miles in nautical measure...I don't relate well to statute readings....

I would say that over 99 percent of the people in the U.S. relate to statute miles, and mpg. And speak English, but if you wanna speak Portugese thats ok to.

litres per 100 kms up here, not mpg. The gallons are bigger up here as well! And that doesn't translate well to nautical life. For non-linear weekend cruising as we do, gph or lph has much more relevance.

kulas44 said:

I would say that over 99 percent of the people in the U.S. relate to statute miles, and mpg. And speak English, but if you wanna speak Portugese thats ok to.

Click to expand...

99% of the people in the US shouldn't captain a cruising vessel either...

No one I know in the maritime professions...just yachties going down the ICW following the magenta line and trip planning via waterway guide....

kulas44 said:

I really enjoy posts like this that tell me how much fuel a particular boat has used. What is less important to me is miles travelled, gallons per hour and totall fuel purchased. MPG is king, period. In Statute miles, which we all understand. And I do agree, if you are stuck to the dock you may be a little peeved at those actually burning fuel, well, suks bein you.

Click to expand...

Actually I use Nautical miles and Gallons Per hour. That is the method to my madness

Greetings,
It gets better...

miles per US gallon → L/100 km: 235 / mpgUS = L/100 km miles per Imp. gallon → L/100 km: 282 / mpgImp. = L/100 km L/100 km → miles per US gallon: 235 / (L/100 km) = mpgUS L/100 km → miles per Imp. gallon: 282 / (L/100 km) = mpgImp.

Further 1"=2.54cm....And the clincher is: one torr is exactly 101325/760 ≈ 133.3 pascals.
So there!

kulas44 said:

I would say that over 99 percent of the people in the U.S. relate to statute miles, and mpg. And speak English, but if you wanna speak Portugese thats ok to.

Click to expand...

Why the insult,? I speak Nautical Miles and I speak English. The US Navy uses Nautical miles both in Surface and Aviation navigation.

You aren't the most correct because you are the loudest...

I can use my burn rate per hour on an ERPM chart to determine best speed for efficiency and use that the estimate my GPH for a very accurate fuel state for cost and distance. I couldn't be as accurate using a MPH fuzzy math guesstimate.

If using charts with latitude and longitude, than it's only logical to use nautical miles and therefore knots.

If using rand McNally maps, then use your odometer.

On another note, the USAF used nautical in Europe, but statute miles in conus. Since air and wind speeds were in knots, that didn't make any sense, but then have I told you about the ROE in Vietnam recently?
Nuff said.

I use nautical miles (knots) cause I'm on a boat!

And knowing fuel consumption is useful, if for no other reason than helping in planning your fuel stops.

MPG is a stupid measure. Dependent variable in the denominator. Better to use volume burned per distance traveled, but whatever.

I burn 1.9gph at 950rpm, 7.7kts, right at 4nmpg. I burn 11gph at 2000rpm, 20kts, right at 1.8nmpg.

I can afford to run fast, but I damn sure need to be in a hurry to do so. If in no hurry, I go slow and enjoy the ride.

And saying the fuel is a small part of the money equation: Absolutely correct. However, once you have bought a boat and secured a slip and done the maintenance, etc, etc, those costs are sunk. Can't control them. Drive the boat fast, slow, or not at all, those numbers don't change (much). But when traveling, you do have a choice at speed and burn rate. And that choice will affect what is in your pocket!!

I can run 7.7, 20, and up to 25kts. I run 7.7. And every now and then just for kicks, it is super nice to knock back some serious miles quick, or shake off some annoying boat behind me!!

Mere mortals do need to consider fuel cost.