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Author Topic: Fuel Consuption  (Read 5167 times)

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CIAO

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Fuel Consuption
« on: July 30, 2007, 08:08:41 AM »

I wander what is the estimated M25 engine fuel consuption on my 1987 C34 fully loaded (cruise mode) I am going down to Baja California. Over there I expect running with moderate currents and winds.
 Ciao, Juan
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sdaly66

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Re: Fuel Consuption
« Reply #1 on: July 30, 2007, 08:34:08 AM »

I burn about 3/4 galon per hour at cruising speed.

I always estimate 1 gallon per hour in order to be conservative,  i'm always on the high side in my estimate.

Hope this helps.
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wind dancer

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Re: Fuel Consuption
« Reply #2 on: July 30, 2007, 08:40:06 AM »

I burn about 1/2 gallon per hour (M25XP). 
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Jay Guard, 1996 Catalina 380, #3, "Aquila", Seattle

Larry Robertie

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Re: Fuel Consuption
« Reply #3 on: July 30, 2007, 08:50:16 AM »

Having my boat just this year I had as a task for myself to figure out the fuel consumption - and how accurate (or not) the fuel gauge is.  

I can't speak directly to your consumption as I have the M35b engine in mine.  But I can tell you that it does vary quite a bit.  For instance, the rated consumption at 2200 rpm is .8 gallons per hour.  If I push it above that (say 2800) when I'm looking to get to the next port in calm waters I've seen .9 gallons.  Two weeks ago we came out of the Narragansett into 12-15 foot choppy waves and a 20 knt. wind on the nose.  I was pushing the engine pretty hard just to stay ahead of the situation.  The consumption rate was 1.1 gallons.

My Catalina 27 had an M18 that burned about .5 to .6 an hour.

I think the 1 gallon per hour estimate, unless extraordinary circumstances, is appropriate.

As for the gauge - It seems to "sit" on full for about the first 5 gallons.  I've estimated it at 5 gallons per 1/4 tank mark thereafter.  Tanks are shaped funny though, and depending on the conditions of the seas you are in the darn needle can bounce all over the place.  Best to keep an engine log.
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Larry Robertie
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Salem, MA

BillG

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Re: Fuel Consuption
« Reply #4 on: July 30, 2007, 09:11:07 AM »

I have an 87 and I think the literature says about .6 gal per hour and I  have found that to be pretty close.
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Bill
Rock Hall, MD

wind dancer

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Re: Fuel Consuption
« Reply #5 on: July 30, 2007, 11:51:16 AM »

Larry, I think the mileage you are getting might be  indicative of the larger engine?  You have a 30 hp engine, while CIAO's is 21hp.

I think BillG's number is probably right on.
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Jay Guard, 1996 Catalina 380, #3, "Aquila", Seattle

Ron Hill

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Re: Fuel Consuption
« Reply #6 on: July 30, 2007, 05:34:22 PM »

Caio : I believe that you've got a M25XP (1986s had an M25 21hp).  I'd figure on .5 gal per hr. fuel consumption. 
I've been using that for 20 seasons and it's pretty much right on!!   :thumb:
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Ron, Apache #788

CIAO

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Re: Fuel Consuption
« Reply #7 on: July 30, 2007, 08:24:31 PM »

Thanks you all

              I intent to sail as much as the wind allows me... I will make myself pretty sure that I won't run out of fuel even if I have to go 4 days without wind power. I guess that is why the cherry cans has been invented.

                                Ciao, Juan
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Ron Hill

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Re: Fuel Consuption
« Reply #8 on: August 02, 2007, 07:15:25 PM »

Caio : I forgot to mention that even if you have only a slight breeze - roller out the head sail. 
You'd be surprised how the torque of the engine drops (along with the fuel consumption) at the same RPM - when that sail fills with only 4 or 5 knots of wind!! 
A thought.   :thumb:
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Ron, Apache #788

sail4dale

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Re: Fuel Consuption
« Reply #9 on: August 04, 2007, 09:40:46 AM »

I suggest when talking fuel consumption you also mention the engine involved. 
I have a Mk II with a M35b engine and get about .8 Gal per hour at 2200 RPM.  That will give me about 6.8 knots.  some times 7 knots in smooth water.  Yes the main up helps!  Does this sond like what others are getting with the same engine?

My fuel gauge is almost worthless.  recent fill up when the gauge registered 1/8 full took 11.5 gal. to the full mark.  :donno:

Anyone with a good solution to gat accurate gauge readings?
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Cat34 Mk II True Luff #1582  2001
San Pedro, CA (Port of Los Angeles)

Stu Jackson

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Re: Fuel Consumption
« Reply #10 on: August 04, 2007, 09:50:21 AM »

Try this for starters: http://c34.org/bbs/index.php?topic=559.0

I had emailed Juan with my often mentioned fuel use spreadsheet.  Anyone wants a copy, email me.  One of these days I'll convert it into a picture file and post it.  (DONE - see the link below)  It completely eliminates the need for a fuel gage.  The fuel gage is linear, the tank gets narrower at the bottom, that's why it seems "off."

Make it even simpler, if you know how much fuel your engine uses, start with that guess and KEEP TRACK of how much you fill up with and how many hours.  You only need do this a few times (don't need to be as compulsive as I am -- 9 years, 43 fuels).  Then you'll know.

1/2 gph = 10 gallons every 20 hours.  Do the math...

Also see: http://c34.org/bbs/index.php?topic=3841.0  FUEL LOG This includes an attachment with the fuel log posted.
« Last Edit: August 07, 2007, 12:12:55 PM by Stu Jackson »
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."
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