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Old 01-25-2014, 12:33 AM   #41
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Doesn't matter a bit what equation you to measure the efficiency of your boat vs. another... as long as you can figure one vs. the other.

The two years we had the Sea Ray Express we used A LOT of fuel.. but had a ball and I knew it wasn't a long term acquisition. On Plane at about 19kts the boat burnt about 30 gph. 45' of leather interior with air conditioning. I had a "mental budget" figured at $ 4000.00 per year for fuel.. and both years that is within $ 100.00 if what we actually spent. Was it expensive? you bet. I spent more per year on fuel than I did the entire time I owned Volunteer!. We did have a blast though!.. now I am back to the 2/3 gph zone in the Ocean Alex.

I prefer to look at boat fuel in "smiles per gallon".. because that is why I boat.
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Old 01-25-2014, 12:36 AM   #42
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Smiles per gallon! +1
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Old 01-25-2014, 12:46 AM   #43
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smiles per gallon! +1
+ 2
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Old 01-25-2014, 06:52 AM   #44
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I'll stick with litres per fortnight . . .
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Old 01-25-2014, 07:49 AM   #45
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A lot of people pretty forceful in opinions where they aren't walking in another's shoes.

Fuel cost DOES mean something to some here and being able to control them contributes to their quality of cruising.

So if you want to say fuel costs are a small part of a persons boating expenses and share your spreadsheets of how you spend your money .....GREAT!

You post probably has NOTHING to do with the discussion between those that ARE trying to control fuel costs.
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Old 01-25-2014, 07:58 AM   #46
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>If in a perfect world you could reach that RPM at WOT. Your boat and prop would be set up for optimal fuel burn.<

Not at all, you would be set up to operate at max hp and have the vessel go as fast as it can.

Probably huge stern wave and really lousy MPG.

The best MPG will be about the sq rt of the lwl, about 1/3 slower and 2/3 less fuel burn.

Operating near max RPM & hull speed is mostly for the rich or sailors where the wind is free.

For most folks the throttle is about the best way to operate at lower cost.

A slick bottom might save 10% , a cruising prop 10%-15% , but with a 65%+ change in fuel burn , just by closing down from full tilt , slow is king.
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Old 01-25-2014, 08:23 AM   #47
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To the original post, I think 2.47 gal per hour is a little high for a Lehman 120 running at 1650 rpm. That's where I run (usually 1700) and I'm at around 1.8 gph.
I don't run at that rpm to save fuel, it's more because that's where my rig "seems" most comfortable.
Fuel cost means something to me, but I consider the difference not significant if I were to run a few hundred rpm more.
In the past I have used nautical miles as my distance measure, however that past 2 seasons I have been on the inland rivers and lakes, and have changed to statute miles while there. It only makes sense as all my charts and guide books use that measure. Why would I want to continuosly do the conversions?
And to me, miles per gallon is the measure that makes sense. That is what I use for planning, again because I don't have to keep doing the math.
There are many tools in the toolbox, use what you are comfortable using. If they are not the same tools I use, I willdo the math to see how it compares.
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Old 01-25-2014, 08:26 AM   #48
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I like mpg, mostly because I am mathmatically challenged and most of my boating is in statute mile areas right now. Sorry to come off a little grouchy yesterday, my BrotherInLaw and I are in the retail propane bidness and I got my a$$ handed to me several times, by customers and suppliers. I'm VERY happy my boat does not run on propane. $5 per gallon. My cost. Anyway, I agree with FF, reaching max rpm is not really the most efficient use of diesel power. It does however keep you from "hurting" the engine. On the flip side you could pick your ideal cruising rpm (most efficient) for the boat and prop, which would probably be seriously overloaded at wot, but fine at a lower setting, and reset the gov. for that rpm. Or just add a simple throttle stop on older mech. injected engines.
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Old 01-25-2014, 08:48 AM   #49
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Love talking fuel burn.

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Nothing...just after over hundreds of thousands and possibly millions of miles in nautical measure...I don't relate well to statute readings....
That's pretty impressive. I spent 22 years in the Navy and made 8 deployments worldwide and have been boating since I was a kid and I haven't racked up that much mileage under my keel. To this day I still use statue miles. Living on the east coast it makes since since nowadays I primarily boat the ICW and planning a few trips to the Bahamas.

Fuel burn is always a concern. I'm still going to travel where I want, but to me it's a little bit of a game to see how low I can burn with 6-71 Detroit's and running a 15kw genny. The best so far was last December. Jacksonville to St. Augustine, just under 7 gallons an hour for a 33 mile trip. Average 8 kts. I never thought that the Amar La Vida would burn that little but since we were heading to Fort Pierce for New Years it was nice to know. However, I completely blew that burn in the Indian river to Cocoa beach where I ran 15-16 kts but still averaged out to 18 gallons total so it wasn't too bad for a 50k pound boat. Entire trip averaged out to 1.3 mpg. I generally use one gallon per mile when trip planning. That seems to keep me out of trouble due to the fact we all know how accurate fuel gauges are!
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Old 01-25-2014, 09:55 AM   #50
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That's pretty impressive. I spent 22 years in the Navy and made 8 deployments worldwide and have been boating since I was a kid and I haven't racked up that much mileage under my keel. To this day I still use statue miles. Living on the east coast it makes since since nowadays I primarily boat the ICW and planning a few trips to the Bahamas.

Fuel burn is always a concern. I'm still going to travel where I want, but to me it's a little bit of a game to see how low I can burn with 6-71 Detroit's and running a 15kw genny. The best so far was last December. Jacksonville to St. Augustine, just under 7 gallons an hour for a 33 mile trip. Average 8 kts. I never thought that the Amar La Vida would burn that little but since we were heading to Fort Pierce for New Years it was nice to know. However, I completely blew that burn in the Indian river to Cocoa beach where I ran 15-16 kts but still averaged out to 18 gallons total so it wasn't too bad for a 50k pound boat. Entire trip averaged out to 1.3 mpg. I generally use one gallon per mile when trip planning. That seems to keep me out of trouble due to the fact we all know how accurate fuel gauges are!
20+ years of flying (probably +500,000 miles right there) plus much OFF that flying of 18 deployments on ships , plus lot's of commercial marine /recreational...you are probably right that it certainly isn't much over a million as I was a helo guy and not a fixed wing guy....still a lot of thinking in terms of Nautical because that's what we used.

For most of that steaming and flying...there was no GPS or LORAN to do the nav for you...much of it was in my mind or scratched notes on a kneeboard....with the ship steaming around and you with not even homing to get back to the ship some days, constant DR was critical. With constant 2 handed flying and no co-pilot or navigator....in your head was the best you had some days. They call it the "old days" for a reason...

Jay Leonard's post is about where I am or about to go...it's easier to let my girlfriend follow the guide books and statute mile marks on the ICW charts so I may switch the mental calcs to statute to keep us thinking together....certainly on some runs or partial runs I worry more about time than fuel consumption...not that it changes my life that much because we are talking gallons difference because the limited time I don't worry about it...but for a years worth of cruising... around 400 hrs at 2gph is 800 gallons at $4 a gallon that's $3200...at 3gph it's 1200 gallons or $4800 or a $1600 difference wich for me is an extra night out a week on my trip and only cuts off maybe an hour or so of travelling every day. The payback of going maybe a knot faster isn't there and does crimp my recreational budget underway.

If I burned 50% more fuel and got there in a half day versus a full day of steaming...and it only cost $1600 more a year....you bet I would find a way to pay for it....but to only save a little time that I have anyway....NOT worth it.

For those that have money...great...I used to have it too....even on a serviceman's salary...but things can change in the blink of an eye...so $1600 for going a little slower is worth it to me and probably others.

Most of this was not intended for you Knotheadcharters....
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Old 01-25-2014, 10:56 AM   #51
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Any discussion of "Miles Per Gallon", be it nautical miles or statute miles, is meaningless unless you're boating on a pond with no wind. Once you leave that pond or the wind kicks up, you have current and wind to deal with. Think of driving a car but the road is moving as well as the car. Going with the current, you use less fuel to go a given distance (over ground). Going against the current, you use more fuel to go the same distance. And of course your boat has no odometer so you have no way of knowing exactly how far you travelled.
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Old 01-25-2014, 11:20 AM   #52
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I like mpg, mostly because I am mathmatically challenged and most of my boating is in statute mile areas right now. .
As mentioned earlier navigation based upon nautical charts, latitude and longitude results in nautical miles being the standard distance measurement. If one uses a Road Atlas you could end up on the rocks.
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Old 01-25-2014, 11:48 AM   #53
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I'm with the group that believes that fuel is a non issue in boating but only because I have a trawler (as opposed to a fast boat) and I rarely use my boat. If I used my boat like some others here, fuel expense will probably be felt and will have some significance. We all boat differently, and have different pocket depths.

Sunset, boats that are rarely used, in my opinion, are likely owned by people that are busy with other life interests, and not because they are afraid of fuel cost or handling their boats. Take myself as an example - I use my boat approximately 6 weekends a year because there are activities that are more important to us for now than boating to occupy our weekends.

I spend about $1000 a year in fuel and how I wish it was more.
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Old 01-25-2014, 11:49 AM   #54
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Any discussion of "Miles Per Gallon", be it nautical miles or statute miles, is meaningless unless you're boating on a pond with no wind. Once you leave that pond or the wind kicks up, you have current and wind to deal with. Think of driving a car but the road is moving as well as the car. Going with the current, you use less fuel to go a given distance (over ground). Going against the current, you use more fuel to go the same distance. And of course your boat has no odometer so you have no way of knowing exactly how far you travelled.

Agree, agree, agree ... but ...

1. The MPG is a pretty good calculated indicator of state of the engine and/or boat configuration on test runs in known environment. Conveys the fuel needs over distance and is as good as GPH (fuel needs over time) since both are mathematically related.

Me thinks ... if you go fast and measure your trip in miles you might prefer MPG, if you go slow and measure your trip in hours you might prefer GPH ... just a matter of preference.

2. Both, MPG and GPH, suffer from the same environment induced inaccuracies. If you consider GPH and the time delta between the time needed to get upriver and the time needed to get back ... you have the same quandary.

3. Regardless of which one you use, either one averages over time and distance traveled. Either one will indicate the same average "score" for a particular boat.
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Old 01-25-2014, 11:53 AM   #55
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Sunchaser ----> +1
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Old 01-25-2014, 11:56 AM   #56
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Mahal ---> no slight intended. I read an article recently that took a survey that suggested that those were the most common reasons for folks partying at the dock.
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Old 01-25-2014, 12:35 PM   #57
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I once ran an OB boat from Prince Rupert to Juneau w no charts, no GPS, no cruise guides, no binoculars and a hiking compass w a needle that quivered. But I knew I burned 3.5gph! And I had a map. And of course it was not calibrated in knots ... nor did I care.

Was a busy year for cruisers and all the charts were sold out. I had just built the boat and it wasn't even finished. Cabin was not done. Had a 4 X 7' temporary cabin to keep things dry and slept under the foredeck.

Knowing my fuel burn per hour was about all I had and I've navigated ever since by that and done well. I bought for the trip a sizable map (put out by the US Forest Service) that they sold to the tourists on the ferries. It was basically green and blue .. land and water. Had a millage bar in the water somewhere (on the map) so if I allowed for all the turns and bends I could figure out basically how far (statute miles) my next planned destination was from where I was starting out. So distance and mpg or gph and speed is all one needs to know. And Tom (Sunchaser) I would have liked to have had a road map or two. But knowing your speed on seawater is often not easy. But mpg or gph works just fine. Frequently in the fall how much daylight left is a limiting factor on how far you can go and if you'll make it that far. gp HOUR may bring us closer to time realities.

I think boaters that are concerned about their nautical image (and we have many here that are) wouldn't be caught dead using statute miles on their boat. You're more salty if you use knots. Less experienced boaters will (of course) use statute miles because they don't know any better. If you're using a chart converting all of one's distances to statute miles must get tiresome after a bit. But if your navigational equipment is calibrated in statute miles it would seem stupid to constantly be converting everything to knots. So I think a non pretentious person person would use one or the other depending on where one was and what one had to navigate with.

But there's no good reason to look down on skippers that use statute miles where it's appropriate. The measure of a statute mile is as accurate as a nautical mile and better to use if your navigational equipment is calibrated in statute miles. With a GPS chart plotter all one needs to do is punch a button and pick w one to use. The temptation is to pick what one is used to and often that is statute miles because of all out land experience. But if you want to communicate w other boaters, the Coast Guard and have fewer troubles w distances and infrastructure relating to maritime issues one needs to buck up and learn the nautical system. But if you struggle and stumble forcing the statute miles to work at sea then perhaps the salty boys have a right to look down on you.

A parting fact is that MPG is not independent of nautical or statute miles. GPH will work equally well w either.
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Old 01-25-2014, 01:17 PM   #58
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Like captain Ron said "we must be close cause I only put in enough fuel to get there and we are almost out" excellent navigation
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Old 01-25-2014, 01:28 PM   #59
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I grew-up(?) using statute miles on land with mpg, no inland water, and nautical miles & knots on the water. Our charts (CHS) were marked in nautical miles & fathoms as were the depth sounder and radar (later acquisitions). Run the "measured mile" to get your boat speed. Knowing gph make allowances for current, wind, etc.gave us what we needed.
NOW,,,the***CHS through our elected ( grafters?) have switched to kilometers and (HORRORS) meters for depth.
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Old 01-25-2014, 01:35 PM   #60
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Ted the metric system is better and the sooner we get there the better.

We're WAY BEHIND in the US.
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