| Author |
Message |
    
Liz Wardley
Visitor
| | Posted on Monday, September 24, 2007 - 03:43 pm: | 
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Does anyone know the fuel consumption at cruising speed for a 225 Ford Lehman engine? Your help would be greatly apreciated. |
captain William Myers 1
Visitor
| | Posted on Tuesday, September 25, 2007 - 11:44 pm: |
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Hard question to answer, if you use a 2000rpm as normal rpm as I do with my Lehman 135. but if you use 1800 or 2200 it would change quite a bit. At 2000rpm I burn about 2 gallons an hour. But its a lower horsepower engine w/ no turbo. I would say 6-8 gallons at 2000rpm. Also what type, lenght, and weight of the hull its in, would help me give you a better answer. |
Liz Wardley
Visitor
| | Posted on Wednesday, September 26, 2007 - 12:27 pm: |
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Hi, thanks for your reply and yes I didn't provide much info. In fact I haven't seen the boat as yet and I am delivering it from Australia up to PNG.
-So the engines are Dual Ford Lehman 225Hp
-She cruises at 8.5 knots and max 10knots
- Length 60 foot/ 18m
- Beam 19 foot/ 6m
- Draft 4.8 foot/ 1.4m
- construction GRP composite.
- Of course the spec sheet doesn't give me a weight but I'd go a guess of around 20 tons.
Any help in greatly appreciated.. Cheers |
CaptainBill
Visitor
| | Posted on Wednesday, September 26, 2007 - 09:34 pm: |
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Liz
My single 44ft is 34 net ton, this boat is much heavier then you think, 60 ton or so. Twin engines pushing that size boat at 8.5 knts you could burn up to 25 to 30 per hour per engine. I'm sorry to admit I don't know what PNG is, or how far or if its agains't pervailing currant, and wind or not. A true ocean going vessel of this size should be carrying 1000 US. gallons of fuel for any trip of extended distance. If this vessel has not been maintained to the highest standards I would think twice. WHen is the last time the fuel tanks where opened and cleaned. If not in the last 2 years I would have it done. Carry as many fuel filter as you can. Would love to hear more about your trip e-mail me direct if you like. As a deliverey captain I understand what your facing. Good Luck |
peter williamson
Visitor
| | Posted on Wednesday, April 09, 2008 - 03:04 am: |
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yes my 50 footer is 45 tonnes and with twin 2725ti's cruising 8.5 knots at 1800 rpm i use about 40 litres per hour ... running on one engine hardly reduces speed but close to halves fuel consumption so i tend to run on 1 and swap every couple of hours |
Paul Sheard
New member
Username: offthepoint
Post Number: 1
Registered: 04-2009
| | Posted on Sunday, April 19, 2009 - 02:14 pm: |
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I am interested in purchasing a 32' trawler yacht [1978] with single Lehman 120 hp. I notice that Lehman 135 fuel consumption is quoted here as 2gph @ 2000rpm, which I assume is cruising speed [7 knots?]. This must be close to the vessel I'm considering - unless the hull is significantly lighter. Am I correct in my assumption? |
Fred Frog
Member
Username: lilypad
Post Number: 44
Registered: 01-2008
| | Posted on Sunday, April 19, 2009 - 04:04 pm: |
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Over the years I've seen some remarkable claims for fuel economy. Generally the person making the claim is trying to sell something.
I have a FloScan meter on my single Lehman 120, inside a 40' Taiwan Trawler. At 1750 RPM I burn 2.2 GPH @ about 7 knots depending on current. This is double checked by fuel purchases and calculated independantly.
A problem you will have with economy in the shorter hull is hull speed. The faster you try to push the shorter hull the more fuel you will burn.
You will not get 2 gph at 2000 RPM. Watch your wallet around those who tell you that you will. And as a side note, 2000 RPM is not a speed you want to run a Lehman at if you are interested in the best longevity. Talk to the VP of Development for the marinization of the Ford Lehman, Bob Smith at American Diesel if you think maybe I'm blowing smoke your way. (Google search American Diesel and get the number)
K |
John Olson
New member
Username: free_bird
Post Number: 2
Registered: 04-2009
| | Posted on Sunday, April 19, 2009 - 06:08 pm: |
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We have just finished our 2nd loop in our boat with twin SP225 turbos. Over some 7000 miles, including going out to the Abacos, and in all conditions we averaged 2.23 miles per gal. We seldom exceeded 1700 rpm. |
Paul
New member
Username: offthepoint
Post Number: 2
Registered: 04-2009
| | Posted on Sunday, April 19, 2009 - 07:43 pm: |
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"A problem you will have with economy in the shorter hull is hull speed. The faster you try to push the shorter hull the more fuel you will burn. You will not get 2 gph at 2000 RPM."[Fred Frog]
Well, according to my calculations [1.4 x square root of waterline length], the theoretical maximum hull speed is 7.4 knots - which should mean cruising at 7 knots at well below 2000rpm [32' hull size being a lot lighter than 40']. |
Fred Frog
Member
Username: lilypad
Post Number: 45
Registered: 01-2008
| | Posted on Sunday, April 19, 2009 - 11:28 pm: |
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Are we talking about a typical trawler yacht with square chines or a displacement hull with round chines where you calculations are closer to accurate. (although even then not an absolute)
In actual practice you will find that the square chined boat (sometimes called semi-displacement)will try to climb the bow wave (plane). And the lighter boat will do that earlier. As you increase speed in the 34' you will start to lift the bow earlier than in the 40' boat. When the bow lifts, the economy drops.
That's of course not to mention that at the 2000 RPM he spoke of, the Lehman will burn more than 2 GPH.
K |
Paul
New member
Username: offthepoint
Post Number: 3
Registered: 04-2009
| | Posted on Monday, April 20, 2009 - 03:16 am: |
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I can see how the waterline length rule doesn't fully apply to semi-displacement trawler hulls - and how the lighter hull will lift earlier. However, if I am happy with a slightly slower cruising speed - say 6.5 knots at <2000rpm - then the advantages of the lighter loading should come into play and give an economical ride of, say, 2.2gph/3mpg. |
Fred Frog
Member
Username: lilypad
Post Number: 46
Registered: 01-2008
| | Posted on Monday, April 20, 2009 - 09:40 am: |
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Yes. You should get 6.5 knots at probably 1700 RPM or maybe lower, 1675 or even 1650. At that RPM your fuel economy will go to 1.9 or so.
What you will do is find a happy medium with how fast you want to go and how much money you want to spend on fuel. I can save money by going slower and sometimes I do when I'm waiting for the tide to turn or waiting for slack at a narrows. But most of the time 1750 is a good middle ground for speed and economy for me.
And we haven't talked about making sure you work the engine hard enough to keep it at optimum temperature or other things that come into play as you look for engine longevity.
K |
Paul
Member
Username: offthepoint
Post Number: 4
Registered: 04-2009
| | Posted on Monday, April 20, 2009 - 10:09 am: |
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OK, so it's a balance between revs and temperature - I know that diesels like to be worked fairly hard. I'll find that out by T & E; so, what 'other things' need to be considered? |
Paul
Member
Username: offthepoint
Post Number: 5
Registered: 04-2009
| | Posted on Monday, April 20, 2009 - 01:21 pm: |
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....that is, apart from oil purity maintenance, being gentle with the gear box, and general servicing, for which I have access to an excellent local engineer. |
Fred Frog
Member
Username: lilypad
Post Number: 47
Registered: 01-2008
| | Posted on Tuesday, April 21, 2009 - 09:27 am: |
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Working an engine "fairly hard" is sometimes misleading on it's face. The engine wants to be up to temperature and be working at an efficient level. So, if you run at 1400 RPM and the temp is at 170 then the cylinder is not as hot as it's designed temp, possibly allowing carbon to build up slowly over time in the ring lands and top or pistons, valves, etc.
The moisture in the oil doesn't get evaporated as quickly. Especially if you typically run short runs which I would put at under an hour. (purely arbitrary number)Do you know someone who runs their boat in the slip for 15 minutes every couple of weeks in the winter? (typical in my area PNW where we are in the water year around) If they don't load the engine by running in gear they aren't building up the heat to clean everything up.
Many engine manufacturers used to recommend running wide open for 15 minutes or so every X number of hours of running. This was to make sure everything was cleaned up. Running at WOT every so often will also alert you to developing cooling problems.
Lehman 120's like clean oil, they like the injector oil changed often (I do mine every 50 hours, the book recommends at least every 100 hours). They like clean fuel even though their tolerances are not as close as modern engines.
Warm up your engine properly. Don't let it idle for too long after a cold start. Start the engine, unplug, untie and idle out. Don't leave the marina, get outside the breakwater and run up to cruising RPM. Instead run it up to 1000 RPM or so and let the heat build up to 160/170, then bump it up to cruising R's. This takes about 10-15 minutes in my boat.
Imagine taking a glass out of the freezer and putting the hottest part of the tip of a propane torch to the side of it immediately. What would you expect to happen to the glass? Or, take the glass out of the freezer and slowly play the feather edge of the flame over the glass, watching the ice crystals melt and run off, then getting a little closer and playing the flame, watching the glass get hotter. Finally you can take the flame and put the tips hottest portion directly on the glass until it melts. Which way would work best for your engine?
The same is true when shutting down. Let it cool while approaching the marina, idle in, let the temp go back down to 160 or so before shutting off. This is a little easier to do since it generally takes about the right time to get in and tied.
K |
