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skydivetom posted 07-26-2012 08:38 PM ET (US)
Hello: I recently posted another thread, Launching and Loading Single-Handed in THE GAM forum. The responses were extremely useful and will help me in my decision-making process for buying the right boat.
Up until this point, I've been doing primarily research on the boat itself and the associated cost for the boat loan. Now, I'm getting deeper into the weeds and do due diligence on the associated costs (storing, insurance, and fuel). Originally, I thought that a monthly fuel budget of $300 would be plenty (and maybe it is). However, when crunching some actual numbers, I was in for a wake-up call on the gasoline expense.
The purpose of this posting is to obtain a sufficient number of data points that will allow me to estimate an average, based on how I intend to use the boat, which will be probably more cruising than fishing. Here's how I came up with my estimates. I pulled engine performance data from BostonWhaler.com for the default engine options of the 190 Montauk and the 210 Montauk. Then, I applied some estimates as to what the monthly fuel costs may be. Below are the calculations for the 190 and 210. Note: I've not extracted the full range of RPM instead, I've just taken four values: slow, medium-slow, medium-fast, full throttle
***************************
190 Montauk (with 115 HP)
Knots | GPH
5.4 | 1.3
10.0 | 2.7
21.4 | 4.0
34.7 | 10.9
The following is based on running the engine for 25 hours/month and a fuel cost of $3.50/gallon:
1.3 GPH * 25 hours * 20% * 3.50 = $22.75
+
2.7 GPH * 25 hours * 30% * 3.50 = $70.88
+
4.0 GPH * 25 hours * 30% * 3.50 = $105.00
+
10.9 GPH * 25 hours * 20% * 3.50 = $109.75
--------------------------------------------
= 22.75 + 70.88 + 105.00 + 190.75 = $389.38
***************************
210 Montauk (with 150 HP)
Knots | GPH
5.3 | 1.2
10.1 | 3.5
24.0 | 6.1
36.0 | 13.8
The following is based on running the engine for 25 hours/month and a fuel cost of $3.50/gallon:
1.2 GPH * 25 hours * 20% * 3.50 = $21.00
+
3.5 GPH * 25 hours * 30% * 3.50 = $91.88
+
6.1 GPH * 25 hours * 30% * 3.50 = $160.13
+
13.8 GPH * 25 hours * 20% * 3.50 = $241.50
--------------------------------------------
= 21.00 + 91.88 + 160.13 + 241.50 = $514.50
***************************

Based on these estimates (I don't know if they're too conservative or too liberal), the monthly estimated fuel costs is close to $400 for the 190 Montauk and more than $500 for the 210 Montauk.
Again, they're based on driving the boat no more than 25 hours per month (which seems a very low number for right now). At the same time, it may be too large of a number given that it's covering 100% of cruising time. Obviously, there's plenty of anchoring time in between.
So, while everyone using the a boat differently (cruising vs. fishing, enjoying slow vs. fast speeds), I'm hopeful to get some feedback as to what a good baseline number maybe for monthly/seasonal cruising hours.
Thank you in advance,
Tom
bloller posted 07-26-2012 10:18 PM ET (US)
I am right about at 50-60 hours of use per year. That is spread out between the months of March and November. I think that is about the average use for the recreational boater. Now if you do hardcore fishing offshore your usage would be way higher. There are also a lot of people who only use their boats on holidays and the occasional weekend in the summer months. I doubt they put 20 hours a year on their engines. 25 hours a month seems high to me.

Teak Oil posted 07-26-2012 10:25 PM ET (US)
I think your numbers are flawed, there is no way you will be at WOT for 20% of the time, that figure will be more like 2-4%.
You will be at no wake speeds for more than 20% of the time most likely also, that will be 30-40% if you do any trolling at all, or rivers and inland waterways.
I have used my 22 Outrage a lot since I purchased it in March, (80 hours or so) and with a 225hp 2 stroke have not had a month over $250 in gas. I use an 8hp kicker for no wake speeds which helps considerably.
boatdryver posted 07-26-2012 11:11 PM ET (US)
I think that even if your monthly fuel costs are accurate, the difference of about $110 per month in fuel expenses is trivial compared to the aggregate of depreciation, insurance, and interest (if there is a boat loan) and maintenance.
Get the boat that serves your needs, meets your budget, and you can tow without changing tow vehicles. Don't worry about fuel.
JimL
Buckda posted 07-27-2012 12:02 AM ET (US)
The general rule of thumb for big boats that I've heard thrown around is 10% of purchase cost, PER YEAR in maintenance and operational expenses (moorage, fuel, insurance, etc) for a seasonal boater. Given that smaller boats are often used more than very large boats, I think that this is a pretty good rule to consider...I've found that with a big trip per year thrown in, it comes close - no big trip, then it's on the high side...
...and you need to use the retail price of a new boat - not whatever deal you got on an old/used boat.
That might also be high based on the high initial cost of a new Whaler these days - and it may throw the whole thing out the window...but give it a shot when crunching the numbers and see how close it comes....
I also agree that the duty cycle of the engine will likely have much more time at idle - like 50 percent...
...and you'll likely operate the boat fewer than 25 hours each month once you get through your initial honeymoon phase with the boat (and the cost realities hit you where it hurts - your wife's shoe budget).
1) Your engine duty cycle will likely reflect a more modest throttle use. See: http://www.continuouswave.com/whaler/reference/ETEC_EngineHistoryReport. html for some real world, no B.S. info on this.
2) I've often heard the "rule of thumb" for boat ownership is to factor in 10% of the overall purchase cost (when new) for the annual maintenance, fuel, storage, etc. costs. ...so if you get your Montauk 190 for around $30K, then you would find that 300/month, when averaged throughout the year, should cover most, if not all of your costs.
Neither of these will be true for every user, but I'm pretty sure that the boat manufacturers figure in 50 hours a year of operation for "normal recreational" users, and I felt like the use of my E-TEC engines, as described above, was pretty "normal"...and I put more like 75-100 hours a year on them, especially that first year when you're in the honeymoon phase.
Your results may vary...
20dauntless posted 07-27-2012 01:04 AM ET (US)
300 hours a year is a lot. I've never done that until this year (I'll do 700 probably), but these numbers are skewed by 3.5 months of living on the boat and cruising from Seattle to SE Alaska.
Remember that you're generally not just driving the boat all day when you're on it. You'll anchor, tie up to docks, or just drift, so engine hours are lower than the actual numbers you'll use the boat.
skydivetom posted 07-27-2012 08:18 AM ET (US)
Plenty of good info here... thanks!!
As Buckda indicated, I can see myself being on a "honeymoon period" for several seasons.
I checked out the RPM profile and adjusted my numbers to
45%, 30%, 15%, and 10%, respectively.
The new fuel consumption estimates are $270 (for 190) and $340 (for 210).
I'll keep on researching additional RPM profiles (using one data point is generally speaking not sufficient). However, if these number hold up, these $$ are much more reasonable.
Again, thanks for all the info... 'much appreciated.
Tom
andygere posted 07-27-2012 11:36 AM ET (US)
I think you are really over estimating how much time the boat will be running, and particularly at the WOT rate of speed.
Using your estimate, you will be traveling 1,882 NM per month in your boat! If you used your boat an average of 20 days per month, this is a bit over 94 NM per day. Your monthly estimate is higher than what many of us will run in an entire year.
Consider that in a typical boating day, a lot of time is spend doing things other than running the boat at a high throttle setting. Looking at the stats from my Outrage 22, I run at WOT about 1% of the time that the engine is running. I've had that particular outboard for about 6 years and have around 300 hours on it.
My guess is that you monthly fuel burn will be somewhere between a quarter and a half of what you estimate, and that's still doing a lot of boating. Bottom line: the difference in fuel used between the two boats is negligible. Buy the boat that you want based on how you will use it, how many folks will typically be on board, on-water conditions where you boat, etc.
bluewaterpirate posted 07-27-2012 12:24 PM ET (US)
We've averaged 430 hours a year (35.9 hours per month) on our 210 Ventura over the last ten years. We use our Whaler about 75% of the time offshore fishing and the other 25% on family outings.
Here are some real numbers on a typical offshore run.
Hours spent on the water: 12
Transit distance/speed: 98 miles - 29 - 32 mph
(dependent on sea state)
Trolling distance/speed: 45 miles - 5 - 7 mph
Average gas used: 69 gallons
Average DFI oil used: 1.7 gallons
Avg gal of gas burned at 32 mph (4300 rpms) 13.5
Avg gal of gas burned at 5-7 mph (1k-1.3k rmps) 1.9
Transit time to and from the fishing grounds averages around 4 hours with the remainder of the time spent trolling).
Our Ventura is powered by a Mercury 225 Optimax (the original motor that came with the boat). When fishing offshore we leave the dock fully loaded at about 5100 pounds (includes 92 gal of gas, 3.3 gal of oil, 10 gal water, 3 souls, 80 lbs of ice, fishing gear, 77 lb liferaft, food/beverages, and assorted safety equipment). Boat and motor weigh in at 3800 lbs.
We run the boat at full throttle for about 10 minutes each underway period the rest of the time on plane is spent at 4200 - 4500 rmps (sweet spot).
If we fish offshore 3 times a month our gass/oil costs average $853.00 (we use nothiing but marine grade gasoline $4.00 per gallon).
Tom
jimh posted 07-27-2012 12:34 PM ET (US)
There is a model for boat fuel usage based on the amount of time spent at various engine throttle settings: the ICOMIA model. The ICOMIA model has been thoroughly discussed in a number of prior discussions. Let me point to one:
http://continuouswave.com/ubb/Forum4/HTML/006191.html
Some engine manufacturers publish the engine fuel flow rate per hour based on the ICOMIA model, called the "ICOMIA five" model because there are five speed points.
If you can get the ICOMIA fuel data for an engine, you can use the data to predict your fuel consumption if you have a good estimate of your seasonal running time.
For example, the ICOMIA figure for my engine is 4.4-gallons-per-hour. Based on my own records, my seasonal use of the boat averages about 70-hours of engine running time. I can estimate my season fuel use as 70 x 4.4 = 308-gallons.
martyn1075 posted 07-28-2012 03:24 AM ET (US)
Tom you might benift from a flow meter. Like yourself I find my budget is real tight and in result I have really payed attention to my performance data. It won't pay the gas bill but it assures me not to worry about it so much. To my surprise it wasnt as bad as I thought and much better than most will believe. In result I can accurately plan a trip and know how much gas I will need to put in the tank it's accurate to the liter.
A boat equipped with a flow meter is extremely useful tool in measuring the amount of gas you burn as well understanding how to operate your boat and it's tendencies to burning gas as well saving gas. It will work with any boat but the larger ones can really benefit greatly from a flow meter. I know if I need to push it that will cost me and how much more at certain rpm changes the equation. You will get really good with it and it becomes less stressfull and more of a challenge like a game.
The biggest IF that will cripple a calculated plan working under a flow meter is unexpected water conditions worsen somewhere in your route in that case the average mpg especially in a large Whaler will start decreasing quickly and the gas bill goes up way up sometimes. It doesnt miss a beat what started out promising ends up costing but in a smaller whaler like the 19 it may not be as noticeable.
Martyn
skydivetom posted 07-28-2012 07:02 AM ET (US)
Some good stuff here... thank for all the feedback.
andygere -- I totally question your calculation of 1,882 NM per month. No idea how you got those numbers.
Based on my calculation (using the modified RPM profile), I'll get 102.33 NM/month with the 190 Montauk and 92.6 NM/month with the 210 Montauk. [Sorry, but I just couldn't leave this unaddressed in this forum]. ;)
Tom
elaelap posted 07-28-2012 12:59 PM ET (US)
Whichever boat you decide upon, mount a kicker and use it as often as you can. This will save a great deal of money on fuel, save putting unnecessary hours on your much more expensive to replace main motor, and will provide get-home power in an emergency.
Between my partnership Revenge 21 and my personal classic Montauk, I put around four or five hundred hours per year on my motorboats, and I use the kickers at least half time. For example, yesterday I fished solo in the Revenge, fairly close to our little harbor. We re-fuel after every use, so I know the exact amount of gas I used. Our boat is powered by a 140 hp four stroke and its kicker is a 6 hp four stroke. I was on the water from 7:30 am to around 1:30 pm -- six hours or so -- and I burned only 5.4 gallons of fuel, since 90 percent of the time I was trolling with the kicker.
Tony
andygere posted 07-28-2012 01:07 PM ET (US)
Tom,
I see my mistake: I calculated each fuel burn @ 25 hours, not a total of 25 hrs. per month. Makes more sense that way, though I still think 25 hours of running time per month is a lot. Even when I'm on the water fishing for a full day, running time is typically less than 2-3 hours.
Peter posted 07-28-2012 06:56 PM ET (US)
I think you will spend more than 20 percent of the operating time at the lowest fuel burn rate in your data array. It will probably be more like 30 percent and your WOT time will be something less than 5 percent as others have mentioned.
In looking at the performance report for the Montauk 190, you will not spend much time between 5 knots and 15 knots because this is the on plane transition zone. You will probably spend 35 to 40 percent of the operating time at 20 to 25 knots.
I think you profile could look more like this:
40
15
40
5
The ICOMIA industry standard operating profile is
Idle = 40 percent
40-percent throttle = 25 percent
60-percent throttle = 15 percent
80-percent throttle = 14 percent
100-percent throttle = 6 percent
Under this profile, a modern fuel efficient 115 HP outboard burns approximately 2.3 GPH. A modern fuel efficient 150 HP outboard motor burns approximately 3.2 GPH.
If we assume that the 190 Montauk and the 210 Montauk powered by 115 and 150 HP motors respectively tend to go the same speed at the throttle load, then the 210 Montauk will use about 0.9 GPH more per hour to do the same tasks. At $3.50 per gallon, the 210 Montauk operating fuel cost is about $3.15 per hour more. Over 50 operating hours, the 210 Montauk will cost just a bit more than $150 more to operate, everything else being equal.

skydivetom posted 07-28-2012 07:42 PM ET (US)
Peter:
Perfect... the information (i.e., 40, 15, 40, 5) you provided is exactly what I was hoping to get from in the thread.
Thanks for much... after having modified the above values (plus 20 hours/month) of usage time, the estimated fuel consumption is much more reasonable now.
Again, thanks!!
Tom
martyn1075 posted 07-28-2012 10:02 PM ET (US)
It sounds more reasonable and we always want more reasonable but the problem is you just dont really know unless you can manage your gas with a meter and a gas log program or simple pen and paper. Over time you will know what you spend and how it works without complication on what others think they know.
For example I had a discussion a few months back on my gas milage and according to a few they had it all figured out, ICOMIA, weight vs Mercury enigine stats vs whatever. My numbers wouldn't work for them lol even though I'm the owner the one that puts the gas in it and manages hours under all different circumstances. What I figured out was they were a whole 1-2 mpg off! It varies in every boat and engine choice as well ocean conditions rpms trim tabs. On average it makes sense and planning a trip you will know what you will need without stress. ICOMIA won't help anyone this way nor can many here unless they have the same boat and motor as well use it the same way. That in itself holds quite a large amount of variance.
It does make for good discussion I guess. Good luck and enjoy!
Martyn
jimh posted 07-28-2012 11:45 PM ET (US)
ICOMIA does not predict fuel economy. If just sets a standard for engine loading so that a reasonable average for fuel flow rate can be determined. Fuel economy in miles-per-gallon is influenced by many things which are not even considered in the ICOMIA standard.
skydivetom posted 07-29-2012 01:21 PM ET (US)
Copy all... thanks!
Another extremely helpful thread.
Again, thanks.
Tom

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Author	Topic: Estimating Fuel Burn
skydivetom	posted 07-26-2012 08:38 PM ET (US) Hello: I recently posted another thread, Launching and Loading Single-Handed in THE GAM forum. The responses were extremely useful and will help me in my decision-making process for buying the right boat. Up until this point, I've been doing primarily research on the boat itself and the associated cost for the boat loan. Now, I'm getting deeper into the weeds and do due diligence on the associated costs (storing, insurance, and fuel). Originally, I thought that a monthly fuel budget of $300 would be plenty (and maybe it is). However, when crunching some actual numbers, I was in for a wake-up call on the gasoline expense. The purpose of this posting is to obtain a sufficient number of data points that will allow me to estimate an average, based on how I intend to use the boat, which will be probably more cruising than fishing. Here's how I came up with my estimates. I pulled engine performance data from BostonWhaler.com for the default engine options of the 190 Montauk and the 210 Montauk. Then, I applied some estimates as to what the monthly fuel costs may be. Below are the calculations for the 190 and 210. Note: I've not extracted the full range of RPM instead, I've just taken four values: slow, medium-slow, medium-fast, full throttle *************************** 190 Montauk (with 115 HP) Knots \| GPH 5.4 \| 1.3 10.0 \| 2.7 21.4 \| 4.0 34.7 \| 10.9 The following is based on running the engine for 25 hours/month and a fuel cost of $3.50/gallon: 1.3 GPH * 25 hours * 20% * 3.50 = $22.75 + 2.7 GPH * 25 hours * 30% * 3.50 = $70.88 + 4.0 GPH * 25 hours * 30% * 3.50 = $105.00 + 10.9 GPH * 25 hours * 20% * 3.50 = $109.75 -------------------------------------------- = 22.75 + 70.88 + 105.00 + 190.75 = $389.38 *************************** 210 Montauk (with 150 HP) Knots \| GPH 5.3 \| 1.2 10.1 \| 3.5 24.0 \| 6.1 36.0 \| 13.8 The following is based on running the engine for 25 hours/month and a fuel cost of $3.50/gallon: 1.2 GPH * 25 hours * 20% * 3.50 = $21.00 + 3.5 GPH * 25 hours * 30% * 3.50 = $91.88 + 6.1 GPH * 25 hours * 30% * 3.50 = $160.13 + 13.8 GPH * 25 hours * 20% * 3.50 = $241.50 -------------------------------------------- = 21.00 + 91.88 + 160.13 + 241.50 = $514.50 *************************** Based on these estimates (I don't know if they're too conservative or too liberal), the monthly estimated fuel costs is close to $400 for the 190 Montauk and more than $500 for the 210 Montauk. Again, they're based on driving the boat no more than 25 hours per month (which seems a very low number for right now). At the same time, it may be too large of a number given that it's covering 100% of cruising time. Obviously, there's plenty of anchoring time in between. So, while everyone using the a boat differently (cruising vs. fishing, enjoying slow vs. fast speeds), I'm hopeful to get some feedback as to what a good baseline number maybe for monthly/seasonal cruising hours. Thank you in advance, Tom
bloller	posted 07-26-2012 10:18 PM ET (US) I am right about at 50-60 hours of use per year. That is spread out between the months of March and November. I think that is about the average use for the recreational boater. Now if you do hardcore fishing offshore your usage would be way higher. There are also a lot of people who only use their boats on holidays and the occasional weekend in the summer months. I doubt they put 20 hours a year on their engines. 25 hours a month seems high to me.
Teak Oil	posted 07-26-2012 10:25 PM ET (US) I think your numbers are flawed, there is no way you will be at WOT for 20% of the time, that figure will be more like 2-4%. You will be at no wake speeds for more than 20% of the time most likely also, that will be 30-40% if you do any trolling at all, or rivers and inland waterways. I have used my 22 Outrage a lot since I purchased it in March, (80 hours or so) and with a 225hp 2 stroke have not had a month over $250 in gas. I use an 8hp kicker for no wake speeds which helps considerably.
boatdryver	posted 07-26-2012 11:11 PM ET (US) I think that even if your monthly fuel costs are accurate, the difference of about $110 per month in fuel expenses is trivial compared to the aggregate of depreciation, insurance, and interest (if there is a boat loan) and maintenance. Get the boat that serves your needs, meets your budget, and you can tow without changing tow vehicles. Don't worry about fuel. JimL
Buckda	posted 07-27-2012 12:02 AM ET (US) The general rule of thumb for big boats that I've heard thrown around is 10% of purchase cost, PER YEAR in maintenance and operational expenses (moorage, fuel, insurance, etc) for a seasonal boater. Given that smaller boats are often used more than very large boats, I think that this is a pretty good rule to consider...I've found that with a big trip per year thrown in, it comes close - no big trip, then it's on the high side... ...and you need to use the retail price of a new boat - not whatever deal you got on an old/used boat. That might also be high based on the high initial cost of a new Whaler these days - and it may throw the whole thing out the window...but give it a shot when crunching the numbers and see how close it comes.... I also agree that the duty cycle of the engine will likely have much more time at idle - like 50 percent... ...and you'll likely operate the boat fewer than 25 hours each month once you get through your initial honeymoon phase with the boat (and the cost realities hit you where it hurts - your wife's shoe budget). 1) Your engine duty cycle will likely reflect a more modest throttle use. See: http://www.continuouswave.com/whaler/reference/ETEC_EngineHistoryReport. html for some real world, no B.S. info on this. 2) I've often heard the "rule of thumb" for boat ownership is to factor in 10% of the overall purchase cost (when new) for the annual maintenance, fuel, storage, etc. costs. ...so if you get your Montauk 190 for around $30K, then you would find that 300/month, when averaged throughout the year, should cover most, if not all of your costs. Neither of these will be true for every user, but I'm pretty sure that the boat manufacturers figure in 50 hours a year of operation for "normal recreational" users, and I felt like the use of my E-TEC engines, as described above, was pretty "normal"...and I put more like 75-100 hours a year on them, especially that first year when you're in the honeymoon phase. Your results may vary...
20dauntless	posted 07-27-2012 01:04 AM ET (US) 300 hours a year is a lot. I've never done that until this year (I'll do 700 probably), but these numbers are skewed by 3.5 months of living on the boat and cruising from Seattle to SE Alaska. Remember that you're generally not just driving the boat all day when you're on it. You'll anchor, tie up to docks, or just drift, so engine hours are lower than the actual numbers you'll use the boat.
skydivetom	posted 07-27-2012 08:18 AM ET (US) Plenty of good info here... thanks!! As Buckda indicated, I can see myself being on a "honeymoon period" for several seasons. I checked out the RPM profile and adjusted my numbers to 45%, 30%, 15%, and 10%, respectively. The new fuel consumption estimates are $270 (for 190) and $340 (for 210). I'll keep on researching additional RPM profiles (using one data point is generally speaking not sufficient). However, if these number hold up, these $$ are much more reasonable. Again, thanks for all the info... 'much appreciated. Tom
andygere	posted 07-27-2012 11:36 AM ET (US) I think you are really over estimating how much time the boat will be running, and particularly at the WOT rate of speed. Using your estimate, you will be traveling 1,882 NM per month in your boat! If you used your boat an average of 20 days per month, this is a bit over 94 NM per day. Your monthly estimate is higher than what many of us will run in an entire year. Consider that in a typical boating day, a lot of time is spend doing things other than running the boat at a high throttle setting. Looking at the stats from my Outrage 22, I run at WOT about 1% of the time that the engine is running. I've had that particular outboard for about 6 years and have around 300 hours on it. My guess is that you monthly fuel burn will be somewhere between a quarter and a half of what you estimate, and that's still doing a lot of boating. Bottom line: the difference in fuel used between the two boats is negligible. Buy the boat that you want based on how you will use it, how many folks will typically be on board, on-water conditions where you boat, etc.
bluewaterpirate	posted 07-27-2012 12:24 PM ET (US) We've averaged 430 hours a year (35.9 hours per month) on our 210 Ventura over the last ten years. We use our Whaler about 75% of the time offshore fishing and the other 25% on family outings. Here are some real numbers on a typical offshore run. Hours spent on the water: 12 Transit distance/speed: 98 miles - 29 - 32 mph (dependent on sea state) Trolling distance/speed: 45 miles - 5 - 7 mph Average gas used: 69 gallons Average DFI oil used: 1.7 gallons Avg gal of gas burned at 32 mph (4300 rpms) 13.5 Avg gal of gas burned at 5-7 mph (1k-1.3k rmps) 1.9 Transit time to and from the fishing grounds averages around 4 hours with the remainder of the time spent trolling). Our Ventura is powered by a Mercury 225 Optimax (the original motor that came with the boat). When fishing offshore we leave the dock fully loaded at about 5100 pounds (includes 92 gal of gas, 3.3 gal of oil, 10 gal water, 3 souls, 80 lbs of ice, fishing gear, 77 lb liferaft, food/beverages, and assorted safety equipment). Boat and motor weigh in at 3800 lbs. We run the boat at full throttle for about 10 minutes each underway period the rest of the time on plane is spent at 4200 - 4500 rmps (sweet spot). If we fish offshore 3 times a month our gass/oil costs average $853.00 (we use nothiing but marine grade gasoline $4.00 per gallon). Tom
jimh	posted 07-27-2012 12:34 PM ET (US) There is a model for boat fuel usage based on the amount of time spent at various engine throttle settings: the ICOMIA model. The ICOMIA model has been thoroughly discussed in a number of prior discussions. Let me point to one: http://continuouswave.com/ubb/Forum4/HTML/006191.html Some engine manufacturers publish the engine fuel flow rate per hour based on the ICOMIA model, called the "ICOMIA five" model because there are five speed points. If you can get the ICOMIA fuel data for an engine, you can use the data to predict your fuel consumption if you have a good estimate of your seasonal running time. For example, the ICOMIA figure for my engine is 4.4-gallons-per-hour. Based on my own records, my seasonal use of the boat averages about 70-hours of engine running time. I can estimate my season fuel use as 70 x 4.4 = 308-gallons.
martyn1075	posted 07-28-2012 03:24 AM ET (US) Tom you might benift from a flow meter. Like yourself I find my budget is real tight and in result I have really payed attention to my performance data. It won't pay the gas bill but it assures me not to worry about it so much. To my surprise it wasnt as bad as I thought and much better than most will believe. In result I can accurately plan a trip and know how much gas I will need to put in the tank it's accurate to the liter. A boat equipped with a flow meter is extremely useful tool in measuring the amount of gas you burn as well understanding how to operate your boat and it's tendencies to burning gas as well saving gas. It will work with any boat but the larger ones can really benefit greatly from a flow meter. I know if I need to push it that will cost me and how much more at certain rpm changes the equation. You will get really good with it and it becomes less stressfull and more of a challenge like a game. The biggest IF that will cripple a calculated plan working under a flow meter is unexpected water conditions worsen somewhere in your route in that case the average mpg especially in a large Whaler will start decreasing quickly and the gas bill goes up way up sometimes. It doesnt miss a beat what started out promising ends up costing but in a smaller whaler like the 19 it may not be as noticeable. Martyn
skydivetom	posted 07-28-2012 07:02 AM ET (US) Some good stuff here... thank for all the feedback. andygere -- I totally question your calculation of 1,882 NM per month. No idea how you got those numbers. Based on my calculation (using the modified RPM profile), I'll get 102.33 NM/month with the 190 Montauk and 92.6 NM/month with the 210 Montauk. [Sorry, but I just couldn't leave this unaddressed in this forum]. ;) Tom
elaelap	posted 07-28-2012 12:59 PM ET (US) Whichever boat you decide upon, mount a kicker and use it as often as you can. This will save a great deal of money on fuel, save putting unnecessary hours on your much more expensive to replace main motor, and will provide get-home power in an emergency. Between my partnership Revenge 21 and my personal classic Montauk, I put around four or five hundred hours per year on my motorboats, and I use the kickers at least half time. For example, yesterday I fished solo in the Revenge, fairly close to our little harbor. We re-fuel after every use, so I know the exact amount of gas I used. Our boat is powered by a 140 hp four stroke and its kicker is a 6 hp four stroke. I was on the water from 7:30 am to around 1:30 pm -- six hours or so -- and I burned only 5.4 gallons of fuel, since 90 percent of the time I was trolling with the kicker. Tony
andygere	posted 07-28-2012 01:07 PM ET (US) Tom, I see my mistake: I calculated each fuel burn @ 25 hours, not a total of 25 hrs. per month. Makes more sense that way, though I still think 25 hours of running time per month is a lot. Even when I'm on the water fishing for a full day, running time is typically less than 2-3 hours.
Peter	posted 07-28-2012 06:56 PM ET (US) I think you will spend more than 20 percent of the operating time at the lowest fuel burn rate in your data array. It will probably be more like 30 percent and your WOT time will be something less than 5 percent as others have mentioned. In looking at the performance report for the Montauk 190, you will not spend much time between 5 knots and 15 knots because this is the on plane transition zone. You will probably spend 35 to 40 percent of the operating time at 20 to 25 knots. I think you profile could look more like this: 40 15 40 5 The ICOMIA industry standard operating profile is Idle = 40 percent 40-percent throttle = 25 percent 60-percent throttle = 15 percent 80-percent throttle = 14 percent 100-percent throttle = 6 percent Under this profile, a modern fuel efficient 115 HP outboard burns approximately 2.3 GPH. A modern fuel efficient 150 HP outboard motor burns approximately 3.2 GPH. If we assume that the 190 Montauk and the 210 Montauk powered by 115 and 150 HP motors respectively tend to go the same speed at the throttle load, then the 210 Montauk will use about 0.9 GPH more per hour to do the same tasks. At $3.50 per gallon, the 210 Montauk operating fuel cost is about $3.15 per hour more. Over 50 operating hours, the 210 Montauk will cost just a bit more than $150 more to operate, everything else being equal.
skydivetom	posted 07-28-2012 07:42 PM ET (US) Peter: Perfect... the information (i.e., 40, 15, 40, 5) you provided is exactly what I was hoping to get from in the thread. Thanks for much... after having modified the above values (plus 20 hours/month) of usage time, the estimated fuel consumption is much more reasonable now. Again, thanks!! Tom
martyn1075	posted 07-28-2012 10:02 PM ET (US) It sounds more reasonable and we always want more reasonable but the problem is you just dont really know unless you can manage your gas with a meter and a gas log program or simple pen and paper. Over time you will know what you spend and how it works without complication on what others think they know. For example I had a discussion a few months back on my gas milage and according to a few they had it all figured out, ICOMIA, weight vs Mercury enigine stats vs whatever. My numbers wouldn't work for them lol even though I'm the owner the one that puts the gas in it and manages hours under all different circumstances. What I figured out was they were a whole 1-2 mpg off! It varies in every boat and engine choice as well ocean conditions rpms trim tabs. On average it makes sense and planning a trip you will know what you will need without stress. ICOMIA won't help anyone this way nor can many here unless they have the same boat and motor as well use it the same way. That in itself holds quite a large amount of variance. It does make for good discussion I guess. Good luck and enjoy! Martyn
jimh	posted 07-28-2012 11:45 PM ET (US) ICOMIA does not predict fuel economy. If just sets a standard for engine loading so that a reasonable average for fuel flow rate can be determined. Fuel economy in miles-per-gallon is influenced by many things which are not even considered in the ICOMIA standard.
skydivetom	posted 07-29-2012 01:21 PM ET (US) Copy all... thanks! Another extremely helpful thread. Again, thanks. Tom