# Westerbeke 27 - Diesel Consumption Rate



## craigtoo (Aug 17, 2007)

Hello,

I'm taking my boat up the ICW in a week or so. 

Sabre 34
approx. 12,000 lbs
Shoal Keel
Westerbeke 27 - 1700 hrs.

If we assume calm conditions, little or no wind - calm seas....
engine is in good working order.

She cruises between 5 and 6 knots at 2100 rpm.

Very roughly speaking...
How many Gallons per hour can I expect to burn?

Again.. I'm not looking for exact numbers.. just a rough idea.

I'm digging through old posts...and the Westerbeke website... to no avail...

Thanks,
Craig


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## Freesail99 (Feb 13, 2006)

I read something saying that a 23 to 27 hp diesel burns on average .33 to .38 gallons per hour. I can't find where I read that at the moment. I was looking at the same trip myself.


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## TSOJOURNER (Dec 16, 1999)

I have a 20 hp Yanmar three popper in a 11,500 pound Irwin Citation 34 and I'm averaging about 2.25 hours to a gallon which is really good.


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## tjaldur (Mar 1, 2008)

As a rule of thumb, a diesel engine uses 0,2 litres of diesel pr. HP/h. That is if the engine if 100 HP then you will use 80% of the total capasity in top revolutions. Assuming that this is 2000 r/min. Then you will use 16 litres/h. If you reduce the speed to 1000 r/min, the consumption will be 4 litres/h.

(Double the speed, square the consumtion, half the speed, squareroot the consumption, interpolate for values in between)


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## craigtoo (Aug 17, 2007)

Free, Citation thanks.. that's what I'm looking for...

tjaldur - Thanks for the information.. .Help me with my math.

27 HP @ 80% = 21.6 HP
21.6 HP x 0.2 Liters / hr = 4.32 literes / hr
3.8 litres / Gallon 

= 1.13 Gallons per hr 
This is way too high.. What did I do wrong?

Thanks again,
Craig


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## Rockter (Sep 11, 2006)

Everything hinges on how fast you motor.
This is not an exact science.
Nurse the motor and budget for about 2/3 US gal per hour.


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## camaraderie (May 22, 2002)

I think that 1/2 gallon/ hour would be a safe and conservative budget unless you are really pushing the engine. 
Of course you will find out shortly! Fill your tank and keep track of your miles and hours till your next fill-up...then simply divide by the number of gallons you take on. It is useful to have both numbers...and on the ICW since everything is done in mile markers...it is useful to know how many miles you get per gallon. 
Bring plenty of extra fuel filters and know how to use them!! Good luck with the trip!


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## billangiep (Dec 10, 2003)

Craig, I helped deliver a 34 Gemini. At 2800 rpm. we burned roughly 3/4 gal. per hr. and a 1 gal. if we pushed it.


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## craigtoo (Aug 17, 2007)

Thanks all..

Cam,
Fuel filters... I'm bringing three of the racor(sp). 

Also a spare water pump impeller.

Any other suggestions welcome.

thanks,
craig


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## camaraderie (May 22, 2002)

Alternator belts!


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## tjaldur (Mar 1, 2008)

The math seems sound to me. If you follow the link below you can see the bitter truth graphically. The speed in knots along the X-axis (horizontally) and the consumption in liters on the Y-axis (vertically). Now the values are for my ship and my engine, but the curve will be the same for any ship. A smaller engine than mine (90 HP) will enter at a lower level. As the ship is pushing close to the hull speed, the curve becomes vertical.

Beregninger


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## chef2sail (Nov 27, 2007)

Craig,
I would conservatively plann on .5-.6 gallons per hour. Trying to figur miles per gallon there are too many vaiables ie cureent with or against, wind with or against, etc.

Like Cam said. Plenty of filters. Do you have a two filter system or just a primary. At least 1 alternaor belt. Habdheld VHF along with the regular one. A marine book with ssrvice marinas. Unlimited BoatUS Towing also.

Good luck to you. Hope to see you on the Magothy in a few weeks. VTW go to the Chesapeake forum on here and look at our Sailnet rondevous June 14&15 in Rock creek. We would love to have you participate.

Dave


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## tjaldur (Mar 1, 2008)

Craig, your hullspeed is 6,7 knots (through the water), squareroot(1,34*34). It is more or less imposssible for your boat to go faster than that. The question is, what is the maximum rpm for your engine? Because it is at this maximum that all the capasity is used. If 2100 rpm is the maximum rpm that your engine can bear, and the speed is between 5 - 6 knots, than either your engine is a wee bit too small, or you need to clean it under the waterline. (provided the engine is working properly and that the propeller is the correct size with the correct pitch).

Anyway, you should aim to go about 1 knot slower than the hull speed, that is around 5,5 knots in your case, that is good for the economi end the engine.


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## sailingdog (Mar 19, 2006)

Tjaldur-

Your hull speed calculation is a bit off. It should be* 1.34 * sqrt (34) *or 1.34 * 5.83 or *7.8 knots*.


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## SailorMitch (Nov 18, 2005)

The hull speed formula is based on LWL and not on LOA. I don't know what the LWL is for a Sabre 34 off the top of my head but using 30 feet as something close the hull speed will be around 7.3 kts.


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## HerbDB (Sep 30, 2000)

I too am getting ready to start north. On my trip south, in a Beneteau 36 center cockpit with a Yanmar 27 HP engine, I averaged 10 statute miles per gallon. My cruise RPM is 2700, which gives me between 7 and 8 SM/hour. I find it convenient to use statute miles on the ICW because that is how the charts are set up.

We are planning to leave Jacksonville the week after Easter. I sure hope the weather is warmer.


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## tjaldur (Mar 1, 2008)

sailingdog said:


> Tjaldur-
> 
> Your hull speed calculation is a bit off. It should be* 1.34 * sqrt (34) *or 1.34 * 5.83 or *7.8 knots*.


Saildog:

You are right. I could not find the squarerootsign in this font, so in the haste I got the parenthesis wrong, thank you. (I was planning to wright the 1/2 behind the parethesis)


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## sailingdog (Mar 19, 2006)

very true...but he had the formula wrong. 


SailorMitch said:


> The hull speed formula is based on LWL and not on LOA. I don't know what the LWL is for a Sabre 34 off the top of my head but using 30 feet as something close the hull speed will be around 7.3 kts.


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## camaraderie (May 22, 2002)

The speed formula is based on waterline length...not boat length and the S34 has either a 26'3" waterline or a 28'3" waterline depending on if it is a Mark1 or 2 respectively. 
This gives 6.87 knots and 7.12 knots as hull speed on the two models.


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## sailingdog (Mar 19, 2006)

Thanks cam.  I can do twice that on a good day.


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## craigtoo (Aug 17, 2007)

sailingdog said:


> Thanks cam.  I can do twice that on a good day.


...and feel like you're on a barge while doing it!   

*duck* *run*

Thanks ALL for the info...! Awesome.

Max RPM on the engine is 2850 rpm. 
She cruises well at about 2000 - 2100
Mark II Hull speed just over 7.1 ...

Have:
BOATUS membership number etc. (Wait.. where is my card?)
Insurance (Allstate also covers towing costs with policy)
Beer
Filters
hand held VHF
Beer
New instruments wind, depth, speed (ST60 thanks Giu or Gui)
New standing rigging
Beer
new bottom (14 coats of Epoxy - thanks Dog)
Garmin 478c (thanks for the recommendation cd)
Beer
back-up hand held GPS
New inflatable life jackets
Beer
Harnesses / jacklines (there will be a wee bit of night time sailing up the pamlico)
New foulies (Henri Lloyd TP2000 or whatever that number is...)
Beer
Warm clothes per "Staying Warm and Dry at Sea" thread.
Loads of guides and charts
Loads of flashlights
Batteries
Beer (Erdinger Dunkles Weizen)
Spotlight and 2 - 12V outlets in the cockpit (one forward to limit night blindness)
Cleaned and serviced Seackocks / plumbing
Good German Bread 
Landjaeger
My Centerboard IS NOT STUCK... But if it did.. Who cares... I can fix it while underway....!!!!!!
and and and... 
Full wiring check and redid (some) grounding / rewired some nav lighting (including masthead light)
Spare bulbs for everything.
Load of hose clamps of random sizes
Nigel's books
Beer
New engine compartment ventilation fan
Beer
New Dock lines
Fenders
Beer
Serviced engine new oil... ran 16 hours already. Purrs like a kitten - Steady temp. Oil pressure behaving well!
New bottom paint - 1 hard 2 ablative - (thanks Fastbottms and chef(s)...or was it SailorMitch?)
Beer
Water pump impeller
iPod(s) / charger / FM transmitter
Tigger...!
http://homepage.mac.com/craigtoo/.Pictures/0223081439a.jpg

There is a bunch of stuff I didn't mention here.. suffice it to say.. I'm much better prepared having hung out here for the last 6 months or so....

Oh... and my brother and Dad drink some weird stuff.. called Scotch? or something... I dunno.. they told me to bring a Gallon of 18 year old Glen Livet(sp) or something. All I know is that it's not beer.... yik.

I'll call the yard tomorrow and tell them to throw in an alternator belt. Thanks for that tip.

Chef
Already signed up for the Chessy raft-up....! Wherever the heck it happens to be....!

Thanks,
craig


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## chef2sail (Nov 27, 2007)

Think you may be short on BEER


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## sailingdog (Mar 19, 2006)

Craig-

Don't know what you sail, but I've never seen a sailing barge that could do 14 knots under sail... your boat probably just handles like one... 


craigtoo said:


> ...and feel like you're on a barge while doing it!
> 
> *duck* *run*


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## chucklesR (Sep 17, 2007)

For what it's worth. I used precisely 62 gallons with my Westerbeake 30b, 74 engine hours - very little idling - mostly running about 2800 RPM. If I had to put a number on it I'd say 68-70 hours at 2800, 3-6 at less than that and 1 hour total time at 1000 rpm/idle.

I calculated at one point that my burn rate was .8 gals per hour at 2800 rpm, 2800 RPM gets me 7.2kts in flat water.


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## craigtoo (Aug 17, 2007)

Got the alternator belt...ready to go..!

Chuckles,
Thanks for the info... Cat's get really good mileage... I bet a monohull wouldn't get near that at 2800.

Dog,
http://thames.me.uk/s01290_files/image008.jpg

There's me boat! Thanks again for all the help... ya big AFOC. (That goes to you too Chuckles..)

craig


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## sailingdog (Mar 19, 2006)

Craig-

I can see why you have such problems sailing upwind... given your boat.


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## craigtoo (Aug 17, 2007)

Can someone please Photoshop the Sabre logo on the sail????

heh...

When I put those "Bat-wings" down... Watch out...!


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## chucklesR (Sep 17, 2007)

It's not the mileage Craig, it's the engine run time that matters.

The major difference is the age of the engine, technology has changed even in the past 5 years to produce a much more efficient diesel.


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## craigtoo (Aug 17, 2007)

chucklesR said:


> It's not the mileage Craig, it's the engine run time that matters.
> 
> The major difference is the age of the engine, technology has changed even in the past 5 years to produce a much more efficient diesel.


Yeah...good point...my 20 yr. old engine can't match the diesels of today.

If I ran my boat at 2800... it would suck down the diesel... heh..

I worked for BOSCH for many years. Do marine diesel engines use high pressure direct injection as do Audi/VW and others? (Bosch invented the technology...)

craig


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