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02-01-2010, 14:58
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#1
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Registered User
Join Date: Dec 2009
Posts: 66
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Average Fuel Usage for 38'ers
Please forgive my ignorance , I am a new member , and am extremely keen to learn as much as possible before purchase .
Im looking at a Cat in the 38ft range .
I have had some confusion with fuel burn amounts .
eg Lagoon claim to use 3lt/hr while Leopard owners are claiming closer to 7lt/hr.
Have I got this right , or are the lagoon threads Ive read possibly refering to per side .
Im not only looking at Lagoon or Leopard , but these are more recognized .
Does anyone know the fuel economy of a few known 38ft cats . I certainly dont want to disregard Leopard if I am simply confused. But that fuel usage would be considered to high for my liking, not that I intend to motor everywhere of course but still is a consideration with our much higher fuel prices here in Aus.
Hope you can help and look forward to hearing from you.
Regards , cheers Darren
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02-01-2010, 16:34
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#2
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Registered User
Join Date: Mar 2008
Posts: 92
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Quote:
Originally Posted by Mate
Please forgive my ignorance , I am a new member , and am extremely keen to learn as much as possible before purchase .
Im looking at a Cat in the 38ft range .
I have had some confusion with fuel burn amounts .
eg Lagoon claim to use 3lt/hr while Leopard owners are claiming closer to 7lt/hr.
Have I got this right , or are the lagoon threads Ive read possibly refering to per side .
Im not only looking at Lagoon or Leopard , but these are more recognized .
Does anyone know the fuel economy of a few known 38ft cats . I certainly dont want to disregard Leopard if I am simply confused. But that fuel usage would be considered to high for my liking, not that I intend to motor everywhere of course but still is a consideration with our much higher fuel prices here in Aus.
Hope you can help and look forward to hearing from you.
Regards , cheers Darren
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You may find it depends on the size of the motors, and whether you are thrashing into the weather or running from it.
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02-01-2010, 17:07
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#3
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Registered User
Join Date: Apr 2007
Location: SF Bay Area, CA, USA
Boat: Privilege 39
Posts: 664
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Our Privilege 39 has Yanmar 3GM30F engines (1990 vintage), which are 3-cylinder fresh-water cooled. They burn a pretty consistent 1/2 gallon per hour per engine...
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02-01-2010, 18:25
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#4
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Registered User
Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 21,188
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All diesels are similar - about 200 gr/hp/hour used. You can judge the hp from how many revs you make (there is a rv / hp chart in engine's specs).
Example:
- 10 hp engine at full revs = 2 ltrs / hr
- same engine at half revs (look up the engine graph, say it is 5 hp at half revs) = 1 ltr per hour
b.
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02-01-2010, 18:57
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#5
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Registered User
Join Date: Dec 2009
Posts: 66
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Thanks guys , anymore info is always good.
I am trying to get an average fuel usage in average conditions , doing an average cruise speed of 6-7 knts. Im thinking this is about the optimum cruise speed and would think most cats could cruise / motor at this speed confortably.
Im mainly thinking this way because the first few years of cruising for me will be weekends and weeks only, so time will not necessarily be in my favour eg , one motor , less speed , less fuel. NO wind.
Thanks again , Im very curious about the Leopard burn , seems alot .
Cheers Darren
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02-01-2010, 19:09
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#6
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Registered User
Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 21,188
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If your engines are modern enough then you can get a digital fuel flow/clock/speed meter that will tell you where the economy speed is. No need to guess.
b.
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03-01-2010, 02:54
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#7
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Marine Service Provider

Join Date: Jul 2007
Location: Amstelveen Netherlands
Boat: FastCat 445 Green Motion
Posts: 1,651
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Using a 30 HP Lombardini during 6 days from the Azores to the gulf of Biscaye ( no wind at all ) we burned 2.5 liters per hour at 6 knots one engine running all the time.
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03-01-2010, 04:58
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#8
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Registered User
Join Date: Dec 2009
Posts: 66
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Fastcat , 2.5lt at 6 knots , thats pretty good. If you run both motors and drop the revs can you achieve the same speed ?
Not to get off the subject of fuel burn because it is of importance to what I purchase , so please keep the info coming .
But , how well does a cat handle running one motor , or one side . Does it put extra stress on other parts eg , rudder etc.
I still think the economy of the Leopard 38 to be high , why do they have such big hp compared to others the same size, (the older ones anyway)my only thought is because they were primarily for charter and maybe motoring more so less stress on larger motors. My thoughts only , dont realy have a clue. Got so much to learn , and loving every minite of it .
Cheers Darren
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03-01-2010, 05:40
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#9
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Marine Service Provider

Join Date: Jul 2007
Location: Amstelveen Netherlands
Boat: FastCat 445 Green Motion
Posts: 1,651
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Hallo Darren, yes off course you can run both motors with lower revs to achieve the same speed but fuel economy suffers big time , same speed 2 motors running 3.5 liter per hour or about 40 % higher fuel consumption and more noise.It handles well with one motor, harbor maneuvering is tough with only one motor running but can be done.
Larger motors come in handy with strong wind on the bows, the windage is high on cats.
In general one can say that a catamaran needs about 6 hp per metric ton loaded weight and that will be enough in most conditions.
Greetings
Gideon
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03-01-2010, 05:48
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#10
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Registered User
Join Date: Nov 2007
Boat: Seawind 1000xl
Posts: 7,461
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On our Sunstar with Yanmar 3gm30's we burn .5 gallons per hour per motor. Under 1 motor the speed is mid to upper 6's. under both motors mid to upper 7's.
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03-01-2010, 08:51
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#11
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Registered User
Join Date: Feb 2008
Location: Darwin, Northern Territory, Australia
Boat: Bob Oram Design, 44C, 13.5m -
Posts: 34
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Quote:
Originally Posted by Mate
Please forgive my ignorance , I am a new member , and am extremely keen to learn as much as possible before purchase .
Im looking at a Cat in the 38ft range .
I have had some confusion with fuel burn amounts .
eg Lagoon claim to use 3lt/hr while Leopard owners are claiming closer to 7lt/hr.
Have I got this right , or are the lagoon threads Ive read possibly refering to per side .
Im not only looking at Lagoon or Leopard , but these are more recognized .
Does anyone know the fuel economy of a few known 38ft cats . I certainly dont want to disregard Leopard if I am simply confused. But that fuel usage would be considered to high for my liking, not that I intend to motor everywhere of course but still is a consideration with our much higher fuel prices here in Aus.
Hope you can help and look forward to hearing from you.
Regards , cheers Darren
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Good Day Mate,
If you are Australian or in Australia, please look at Australian designs, there is more variety than any where else in the world. Be aware that the designs you are looking at are primarily for charter use and are in the main heavy for size.
Regards
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03-01-2010, 10:04
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#12
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Registered User
Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 21,188
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Running one engine then giving it a break when running the other I believe a common practice on cats. Have not heard any issues related to stress or anything. Service, oil check-up etc. -wise you can't beat it. One of great advantages of a cat over most monos.
b.
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03-01-2010, 10:10
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#13
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,766
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"Our Privilege 39 has Yanmar 3GM30F engines (1990 vintage), which are 3-cylinder fresh-water cooled. They burn a pretty consistent 1/2 gallon per hour per engine... " Yep, our Lagoon 42 with the same engines burned about the same amount as that, boat was very heavily loaded also... if the wind was blowing harbor manuevering with one engine would not work. I would have liked a little more horsepower personally, although the boat moved along well in all sea states... If your builder offers a little larger engines I would seriously think about them. The fuel penalty would be very small...
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03-01-2010, 11:21
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#14
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Registered User
Join Date: Jun 2007
Location: kefalonia ,ionian islands
Boat: Solaris Sunstar 38, Wild Honey
Posts: 150
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more sunstar fuel figures ....
Quote:
Originally Posted by smj
On our Sunstar with Yanmar 3gm30's we burn .5 gallons per hour per motor. Under 1 motor the speed is mid to upper 6's. under both motors mid to upper 7's.
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My 10hp v/pentas use 1 litre per hour each and can scoot along at 5 knots using only 1 engine . 2x engines = 2.5 litres per hour at 7 +knots
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03-01-2010, 13:59
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#15
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Registered User
Join Date: Dec 2009
Posts: 66
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Gidday again , These are the sorts of figures I thought I was reading and make cat ownership all the more appealling for cruising . To me.
Why would the leopard then be so high , one spec I read said 2 gallens per hour . In my turms thats over 7.5ltr / hr , far to high . Are there any leopard owners who can verify my findings. I may contact the owner if posible and make sure it wasnt just a typing error.
Keep it coming , I find this very interesting.
Thanks for all your comments so far , cheers Darren
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