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tpbrady



Joined: 08 Feb 2005
Posts: 891
City/Region: Anchorage
State or Province: AK
C-Dory Year: 2005
C-Dory Model: 25 Cruiser
Vessel Name: Bidarka II
Photos: Bidarka
PostPosted: Tue Nov 08, 2011 8:09 pm    Post subject: Reply with quote

20Dauntless

It is engine loading. Once I determined what it was, I started looking at props and watching the fuel flow meter. That's when I found the Quicksilver 14p 3 blade stainless as the combination that went best on my 22 loaded heavily. That let me cruise at 12-14 mph at around 3800 rpm and 4 mpg. As we used up fuel, water, wine/beer, and food the speed would creep up to 16-17 mph at 4000 to 4100 rpm before fuel consumption went up through the roof. They really need a little peanut light to tell you when you are in lean burn so you always operate with the light on unless you want to go really fast.

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22 Cruiser Bidarka 2004-2009
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berryst



Joined: 14 Aug 2011
Posts: 135
City/Region: Kingston
State or Province: WA
C-Dory Year: 1985
C-Dory Model: 22 Angler
Vessel Name: Margaret Ann
Photos: Sea Major
PostPosted: Wed Nov 09, 2011 11:50 am    Post subject: Reply with quote

There is a lot to learn here especially when pulling in the the fuel dock. No One wants to take out a second mortgage to fill the boat.

I have begun to look at fuel meters but as always this is complicated too. Does anyone want to suggest a flow meter?

I am trying to decide like we all do on the optimum speed for long distance travel balancing patience and economy. Factors, like I suspected include the obvious weight issue and the less obvious planing hull factor. This is all juxtaposed against tide and wind when timing is everything. It is not an easy answer.

If nothing else I will bring these fuel burn charts on my proposed 850 mile trip around Vancouver island to see how my results stack up

Chris

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irlboater



Joined: 26 Nov 2009
Posts: 47
City/Region: Melbourne Beach
State or Province: FL
C-Dory Year: 2000
C-Dory Model: 22 Cruiser
Vessel Name: Salty
Photos: Salty
PostPosted: Thu Nov 10, 2011 8:20 am    Post subject: Trip Fuel Statistics Reply with quote

I am just returning from a trip up the ICW from my home waters of the Indian River Lagoon to Savannah, Georgia and back via the St John's River to Lake Harney where I had a buddy pick me up with the trailer. I spent two weeks on board. I have a 2000 22' Cruiser with a 2000 carbureted Honda 90. Here are some of the statistics from that trip:
Total miles: 820 miles
Total fuel used: 189 gallons
Miles per gallon: 4.34 mpg
GPS total moving time (approximate): 60 hours
Average price for fuel: $4.37 per gallon
Total amount spent on gas: $826

On average it costs me $1.00 per mile to go on a trip in my C-Dory. This was all sheltered waters with only a few slow speed zones. I've gotten similar mpg numbers from my trip to The Bahamas last summer. Although the fuel cost more over there.
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berryst



Joined: 14 Aug 2011
Posts: 135
City/Region: Kingston
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C-Dory Year: 1985
C-Dory Model: 22 Angler
Vessel Name: Margaret Ann
Photos: Sea Major
PostPosted: Thu Nov 10, 2011 10:25 am    Post subject: Reply with quote

irl boater
What were your speeds and how did you track your miles. I assume the boat was fully loaded
Chris
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irlboater



Joined: 26 Nov 2009
Posts: 47
City/Region: Melbourne Beach
State or Province: FL
C-Dory Year: 2000
C-Dory Model: 22 Cruiser
Vessel Name: Salty
Photos: Salty
PostPosted: Fri Nov 11, 2011 9:32 pm    Post subject: Reply with quote

My average speed according to my GPS was 13 mph. I ran at 20 -23 mph for a lot of the trip. Total miles was calculated using GPS and backed up by ICW mile markers on my charts.
We were loaded for a two week trip. I guess that means we were fully loaded. It didn't seem like we were over loaded. Minimal gear for cruising, boat camping style.
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JamesTXSD



Joined: 01 Mar 2005
Posts: 7444
City/Region: from island boy to desert dweller
State or Province: AZ
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: "Wild Blue" (sold 9/14)
Photos: Wild Blue
PostPosted: Fri Nov 11, 2011 10:11 pm    Post subject: Reply with quote

Some leisurely cruising today: 26.8 miles according to the GPS, 4.2 gallons of fuel used, according to the fuel flow meter. Trying for best economy, I kept RPMs at 1800 max, which resulted in speeds from 5.5 to 6.4 knots. That works out to 6.38 mpg... as long as you aren't on a schedule. I used the autopilot for a good portion of the day, idled around while we watched the dolphins for a while, tossed out the anchor and shut down for lunch, but mostly we just enjoyed the beautiful day and being out on the water.

While our landlubber friends would be appalled with 6.38 mpg, it seems pretty darn good for a boat. Of course, not the "hair blowing in the wind" (maybe that's where my hair went?), spray flying scenes you see in most boat advertisements, but what a nice day. Very Happy

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breausaw



Joined: 18 Jan 2006
Posts: 1222
City/Region: Anchorage
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: Triple J
Photos: Triple J
PostPosted: Sat Nov 12, 2011 1:04 am    Post subject: Re: Trip Fuel Statistics Reply with quote

irlboater wrote:
I am just returning from a trip up the ICW from my home waters of the Indian River Lagoon to Savannah, Georgia and back via the St John's River to Lake Harney where I had a buddy pick me up with the trailer. I spent two weeks on board. I have a 2000 22' Cruiser with a 2000 carbureted Honda 90. Here are some of the statistics from that trip:
Total miles: 820 miles
Total fuel used: 189 gallons
Miles per gallon: 4.34 mpg
GPS total moving time (approximate): 60 hours
Average price for fuel: $4.37 per gallon
Total amount spent on gas: $826

On average it costs me $1.00 per mile to go on a trip in my C-Dory. This was all sheltered waters with only a few slow speed zones. I've gotten similar mpg numbers from my trip to The Bahamas last summer. Although the fuel cost more over there.


That is about as good of fuel economy as can be expected with your setup. I have the same motor although newer but still it’s the same. Interesting to see how much difference weight plays into the equation. Best I have ever got is 3.6 MPG on any given weekend, but that’s fine with me. We are usually heavily loaded with tender, kicker, tender motor, large iced cooler, outdoor gear, fishing gear, shrimp pots, and usually 15 to 25 gallons of extra fuel.
Sometimes loaded out of port I can only make 20 mph at 90% throttle, returning with light fuel and water the same speed is achievable at 75% throttle.
These days I really don’t care much about fuel economy, life is too short.

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2007 22ft C-Dory Triple J 2007-2012
2007 25ft C-Dory Triple J 2012-2018
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colbysmith



Joined: 02 Oct 2011
Posts: 4523
City/Region: Madison
State or Province: WI
C-Dory Year: 2009
C-Dory Model: 25 Cruiser
Vessel Name: C-Traveler
Photos: C-Traveler and Midnight-Flyer
PostPosted: Sun Apr 22, 2018 5:49 pm    Post subject: Reply with quote

Thought I'd reopen this thread, rather than starting a new one. I've been monitoring my fuel consumption, and after a year or so, here are my numbers.

I have a 2007 CD-22, with the Mercury 115hp 4 stroke EFI. I'm probably about as heavy as most other boats my size with the larger engine. I've been running a Permatrim on the outboard, and mostly run regular 97 octane gas. I've switched between 2 props. A 4 blade: Solas Rubex 4 Blade Aluminum 13.25" dia. X 13" pitch SR, and a 3 blade: : 14 x 13 Mercury Black Max Aluminum. Over the past year, these are the numbers I came up with.

4 Blade, running all speeds (average fuel use) came out to about 3.5 mpg. Running the Chicago River last year, where I was doing hull speed (5 mph) a little more than half the time, I got about 3.8 mpg.

This past March, I put the 3 blade on before going down to the St. John's River gathering. Running mostly hull speed (5 mph), I got about 4.7mpg. Then in Arkansas in April (both these times, relatively cooler weather), running mostly on plane (18-20mph), 3.9mpg. It appears that perhaps the 3 blade is just a tad bit more fuel efficient than the 4 blade. Also, unless running the entire time at hull speed, you don't gain much if you are still running on step half the time. Put this in Gallons per hour, and if I did my math right, it breaks down to 1.06 gph at hull speed and about 4.7 gph at planning speeds. While mpg is improved doing hull speed, it is also taking about 3-4 times longer to get somewhere. Mr. Green

Colby
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Sun Apr 22, 2018 6:25 pm    Post subject: Reply with quote

Colby with as many variables you had: different props, different rivers, current, wind, amount at hull speed (whoever that is--many C Brats seem to think it is 8 knots, yet is is really in the 5 or so knot category..) etc. I am not sure you can really come to any conclusions unless you do either fuel consumption tests with a calibrated container, or a calibrated fuel flow meter.

How about speed vs RPM graph to start with for each prop?

In the C Dory it seems to vary from different boats also. The C Dory 22's seem to be most efficient at a mid range speed. The 25's seem to be more efficient at higher speeds (from several C Brats own curves).

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Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018 to Oct. 2021
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ssobol



Joined: 27 Oct 2012
Posts: 3358
City/Region: SW Michigan
State or Province: MI
C-Dory Year: 2008
C-Dory Model: 22 Cruiser
Vessel Name: SoBELLE
Photos: SoBelle
PostPosted: Sun Apr 22, 2018 7:05 pm    Post subject: Reply with quote

I have a FF sensor on my 22 with a BF90D, above 4000 rpm the mpg doesn't change much. Usually we travel in the range ~18-20 mph. If conditions allow we will go faster, but the usual speed range works best for the conditions we normally encounter. The usual mpg is 3.3-3.5.

I use the standard Honda 3 blade prop.
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Marco Flamingo



Joined: 09 Jul 2015
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City/Region: Seattle
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C-Dory Year: 2004
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Vessel Name: Limpet
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PostPosted: Sun Apr 22, 2018 7:08 pm    Post subject: Reply with quote

20dauntless wrote:
I don't have a fuel flow meter on board so I don't have precise figures, but this has been my experience based on 300 or so hours.


Before I found a NOS Faria Fuel Management system (no longer made) for my boat, I bought one of these for fuel.

http://www.digisavant.com/PDF/DF0671L-34-Spec.PDF

The company makes many different variations, but I found a "micro flow fuel" version that is supposedly accurate to about .5 gallon per hour. It hooks up just like the Faria, but is powered by AA batteries and doesn't have a nautical looking gauge for the helm. It was about $50. By far the cheapest fuel monitoring gauge I found (because it isn't just for boats). It could be used to generate a table and then removed from the fuel line if you didn't want a permanent install.

I use mine some for economy but mostly for a really accurate fuel tank reading. I know to the liter how much to refill without a spill. It usually shows "zero gallons per hour" usage at slow hull speed. But after a few hours of that my total gas usage will have dropped a liter so I know that it is registering something even when it reads zero.

I have never had to use the Digiflow, but I'm now addicted to the Faria and would install it if the Faria goes out. The sending units look very similar, but the possibility of the Digiflow sender working with the Faria gauge isn't likely.

Mark
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colbysmith



Joined: 02 Oct 2011
Posts: 4523
City/Region: Madison
State or Province: WI
C-Dory Year: 2009
C-Dory Model: 25 Cruiser
Vessel Name: C-Traveler
Photos: C-Traveler and Midnight-Flyer
PostPosted: Sun Apr 22, 2018 8:33 pm    Post subject: Reply with quote

Bob, there are a lot of variables, and I think you realize the time and cost it would take to do an exacting test! Surprised However, I think over a length of time, one can get a pretty good feel for what their average fuel flow is. And in reality, isn't that really all that is important, since nobody is going to run in perfectly controlled conditions? The result of my earlier fuel monitoring is what I posted. I think I can safely use the figures of 3.5 or 4.7 when figuring out how far I can go between gas stations. If I'm hull speed the entire time, I'll use the 4.7. Or if I know I have to go 200 miles between gas pumps, I'd better carry another 5 gallons of gas, and plan on only doing 5 or 6 mph. OTOH, if I only need to go 140 miles between gas pumps, let er rip! Mr. Green The 3 blade vs. 4 blade thing may not be as accurate, since the only data I have was the last two trips. Of course one of those was mostly at the hull speed of 5-6mph, so it might be nice if some time this summer I try using the 4 blade again at the slower speeds to see if it performs the same as the 3 blade.
Regarding River current, yes that is a factor, but again, averaging while going both up and down current, I think works ok. I think it gives a good representation of what I can expect in tidal waters of the same currents. I just need to realize that current will have an effect on my mileage!

Talking with others, and finding out what they are pumping into their tanks at the same time I am, seems like the 3.3-3.5 mpg range is about what our 22's get, when running faster than hull speed.

One other note, regarding fuel flow sensors in the fuel line. With an EFI outboard, they will not be accurate, except perhaps for an average over time. At least with my Merc, it has an internal fuel module that fills with fuel, then stops until it reaches a certain point, before filling again. So any inline fuel flow meter before that fuel module is going to read zero at times when it's not filling with fuel, and then what ever the max fuel lift pump input is when it needs fuel.Very Happy Colby
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Sun Apr 22, 2018 10:18 pm    Post subject: Reply with quote

Yes, Colby, the injected engines, have a minor challenge, but the average over a period of time works out quite accurately. I have had fuel flow meters on several injected engines, and the fuel flow gives you a lot of information--especially if you are going to AK! (Where there may be marginal runs between fuel stops, and unpredictable conditions).

The "average" you have fine works OK for reasonably smooth waters, and hopefully you have a way of knowing to some degree what the river currents are doing. But there are times when weather conditions will make a huge difference in your fuel consumption.

Here is a fuel flow compilation from the C Dory 25 Sea Weed, taken over several days up and down a mild current area with the boat loaded for cruising. The owner has a good idea what the consumption will be at various RPM. (Weather will still have some effect).



The owner also made curves for RPM vs consumption and RPM vs speed.
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ssobol



Joined: 27 Oct 2012
Posts: 3358
City/Region: SW Michigan
State or Province: MI
C-Dory Year: 2008
C-Dory Model: 22 Cruiser
Vessel Name: SoBELLE
Photos: SoBelle
PostPosted: Sun Apr 22, 2018 10:22 pm    Post subject: Reply with quote

colbysmith wrote:
...

One other note, regarding fuel flow sensors in the fuel line. With an EFI outboard, they will not be accurate, except perhaps for an average over time. At least with my Merc, it has an internal fuel module that fills with fuel, then stops until it reaches a certain point, before filling again. So any inline fuel flow meter before that fuel module is going to read zero at times when it's not filling with fuel, and then what ever the max fuel lift pump input is when it needs fuel.Very Happy Colby


This only occurs at low engine speeds. My Honda engine does this. At idle the fuel flow will alternate between some value and zero as the low pressure pump cycles. Once the engine speed is above about 1000 rpm, the fuel flow out of the engine fuel accumulator needs to be constantly refilled and the FF reads whatever the fuel flow is (not the max pump lift). My FF meter seems to be pretty accurate.

The amount of fuel held in the engine is basically what is in the fuel filter and internal water separator and doesn't amount to a whole lot of fuel.
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colbysmith



Joined: 02 Oct 2011
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City/Region: Madison
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C-Dory Model: 25 Cruiser
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Photos: C-Traveler and Midnight-Flyer
PostPosted: Sun Apr 22, 2018 11:08 pm    Post subject: Reply with quote

I like that chart Bob. Just don't have the time or equipment to be that accurate right now. Ideally I would like to hook my Merc up to the smart gauge capability on my Garmin GPSMAP chart plotter. However, I don't believe my outboard has the transmitter or "box" to currently do that. I started to look into it some a year or two ago, but didn't get far. Perhaps I need to delve into it again this year. Colby
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