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Crow

Diesel fuel consumption

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Crow    12

I've timed the km marker boards on the witham.  And it's taking 8 mins / km. I need to work out my throttle position to get a 5 mph position may be I was going to fast on my previous test.  What i did do was fill a liter tin and run it dry   , and 

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Crow    12

You were right about coming back there's quite a bit of flow on ,and weed . In the end going it used 5 gall going 50 km. mostly at 6 km/ hr  will see what I used on return to lincoln tomorrow, but we came back at 4.5 to 5 km

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Tony Brooks    593
11 hours ago, Crow said:

I've timed the km marker boards on the witham.  And it's taking 8 mins / km. I need to work out my throttle position to get a 5 mph position may be I was going to fast on my previous test.  What i did do was fill a liter tin and run it dry   , and 

Thats what I thought you may have done - see my first post in this thread. Doing that is no good on a diesle unless you also redirected the leak back that normally runs to your tank into the Litre can. I think half your fuel wet back to the tank,

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Crow    12

Tony ,since I put that engine in nothing comes out the spill pipe ,may be the odd drip , and I mean odd drip every 1/2 hr,don't know what that's all about but it runs well enough,regarding prop size may be I could go to a 14 inch ,it's a bit hit and miss,I put all data in to Vic prop and other sites ,Jan (Dislandra )  assisted with calcs as it's his hobby/ job   ,trouble is at £200 a shot for a prop I'll maybe leave it as it is,I've a real worn out 10 inch unknown pitch,but good boss,I might make and weld some bigger blades on it over winter just for the hell of it,and balance it on a motorbike wheel balancer ,true up in lathe ,maybe it's the shape of hull/ swim that's causing a load of drag.what I can say is it's better on fuel than the outboard was,I can charge battery's ,and gas oil is cheaper than petrol,I'm not living on it ,it's only a weekend toy so overall fuel isn't really a issue but was just curious as to what the average boat used per hr,thanks all for your comments and input,nick 

 

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Tony Brooks    593

I think Vetus also spill back from the injector pump inlet or Y connector near the fuel filter, not just the injector leak off pipe. The fuel from the injector leak off will be much as you say with good injectors but the spill from the the low pressure side will be far more. Your engine may not have this spill and if it does not then that could explain a lot about your previous problems in that there would be no way for the system to self vent itself of small amounts of air. Olaese confirm you are talking about the total return to the tank and not just the injector leak off pipe.

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ditchcrawler    379

I have a Beta BD3 and I get enough diesel back through the leak off to keep the Dickinson running. There is also a spill from the top of the filters to bleed them.

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Crow    12

I'll photo all items when I get Moored up,but there is only 1 spill/ return and that's the one I'm talking about ,I can't see, or understand it ,although I said it's a vetus ,it's a L3e Mitsubshi out a gang mower(same base unit) ,maybe vetus modify filter housings / pump fittings accordingly

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Bargebuilder    23

Hi Crow,

I actually run a 25hp 3 pot diesel. It is a direct shaft drive which might be a bit more efficient than a 'z' drive, but probably not much. The cruiser it drives is 30ft long with a 6'10" beam with a fairly shallow 'v'  shaped hull profile. I keep a marine gps on board which I always have switched on whilst I am cruising so I know exactly what speed I am doing, together with the exact number of miles I cover and the exact average speed, both whilst actually moving and also whether moving or stationary but with the engine running.

The Vetus will push the boat along at 4mph with engine revs of 1450 in fairly wide, fairly deep canals, but in shallow, narrow canals it needs 1600rpm. The engine consumes between 0.5 and 0.6 litres per hour at these speeds/rpm levels. Over the last 600 miles my average speed overall has been 1.7mph including time spent stationary in locks etc.

If I back the revs down to just 1200rpm the boat's speed only drops to about 3.5 to 3.8mph, for a considerable saving in fuel, but cruising at 4mph suits me very nicely as the engine purrs nicely and the boat handles brilliantly at this speed. Anyway, the extended running of 'modern' diesels at low engine revs is rather bad for them, leading to bore glazing.

Most narrow boats are very understanding of the different characteristics of grp cruisers and courteously wave us past; so thank you everyone.... 

I have taken the boat onto rivers with higher speed limits, but to achieve just 5mph I need 2000rpm from the engine and three times as much fuel, more noise and much gurgling and wash.

As I said, 4mph is optimum for this boat and in an average cruising day of 6 hours, the Vetus M3.10 only costumes about 3 litres of diesel; cheap hobby!

 

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Crow    12

Thanks for that,it's made me feel worse than ever,after a good run last weekend from Torksey to Boston  50 k. I used 4 1/2 gallon each way ,I need to slow down a bit  and try to find a 14 inch prop,I've only just payed £200 for a 13 x8. You live and learn do I get a 14x8 or 

13x9.  I think 14x 9 would kill the engine,who knows ,it's a dear trial and error 

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Bargebuilder    23

Hi Crow,

Have you tried entering the information into a propeller sizing calculator such as the one on the vicprop.com Web site?

I put in what I thought might be your figures and the recommended prop size was even bigger!

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Naughty Cal    728
9 hours ago, Bargebuilder said:

Hi Crow,

I actually run a 25hp 3 pot diesel. It is a direct shaft drive which might be a bit more efficient than a 'z' drive, but probably not much. The cruiser it drives is 30ft long with a 6'10" beam with a fairly shallow 'v'  shaped hull profile. I keep a marine gps on board which I always have switched on whilst I am cruising so I know exactly what speed I am doing, together with the exact number of miles I cover and the exact average speed, both whilst actually moving and also whether moving or stationary but with the engine running.

The Vetus will push the boat along at 4mph with engine revs of 1450 in fairly wide, fairly deep canals, but in shallow, narrow canals it needs 1600rpm. The engine consumes between 0.5 and 0.6 litres per hour at these speeds/rpm levels. Over the last 600 miles my average speed overall has been 1.7mph including time spent stationary in locks etc.

If I back the revs down to just 1200rpm the boat's speed only drops to about 3.5 to 3.8mph, for a considerable saving in fuel, but cruising at 4mph suits me very nicely as the engine purrs nicely and the boat handles brilliantly at this speed. Anyway, the extended running of 'modern' diesels at low engine revs is rather bad for them, leading to bore glazing.

Most narrow boats are very understanding of the different characteristics of grp cruisers and courteously wave us past; so thank you everyone.... 

I have taken the boat onto rivers with higher speed limits, but to achieve just 5mph I need 2000rpm from the engine and three times as much fuel, more noise and much gurgling and wash.

As I said, 4mph is optimum for this boat and in an average cruising day of 6 hours, the Vetus M3.10 only costumes about 3 litres of diesel; cheap hobby!

 

A boat with a stern drive should in theory be more efficient than a boat with a shaft drive.

7 hours ago, Crow said:

Thanks for that,it's made me feel worse than ever,after a good run last weekend from Torksey to Boston  50 k. I used 4 1/2 gallon each way ,I need to slow down a bit  and try to find a 14 inch prop,I've only just payed £200 for a 13 x8. You live and learn do I get a 14x8 or 

13x9.  I think 14x 9 would kill the engine,who knows ,it's a dear trial and error 

100km to 9 gallons of fuel isn't that bad!

11km per gallon or 7 miles per gallon.

About as good as we ever get on the canal.

On that run when we can get a bit more revs on and the speed up a bit (6mph limit) we usually average about 5mpg. 

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Bargebuilder    23

Just found the fuel consumption curve for the Beta 25 and at 1400rpm it does 0.5l/hr, at 2900rpm it does 3l/hr.

Shorter boats are 'harder' to push through the water than longer ones, with the beam, draft and Hull shape also having a big effect. The propeller is critical, but certainly not the only reason for poor fuel consumption. 

Are the injectors atomising the fuel efficiently? 

What revs were you showing for the trip?

 

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Crow    12

Injectors all done  at Parkinson's, they charge you well for the pleasure of telling you there ok, I haven't got  a Rev counter on it,but I'm on Trent next week so will hold my old hand held smiths one on the crank end and note throttle positions at various revs,14 inch is maybe the biggest prop Enfield do as it's getting a bit near the cavitation plate,leg ratio is 1.6:1 waterline length 23 ft  average draft 25 inch.  Beam 6 -6". Weight 3000 kg.  I think max touque is at 18 /1900 of top of my head ,it's a queer old swim and shape but if you look from underneath the bows to the stern and prop on land ,the props all in view.  well , either side a narrow extended  knife edge keel I fitted. I just posted the question to get some idea of other people's consumption , I'm not going to lose sleep on it but it just niggles me a bit that I could get more,     cal, I feel better now that I'm getting 2 mpg more than you ,no seriously for what my old home made boat and engine/ drive set up is it's near enough just to have a few weekends away from working.Nick

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Tony Brooks    593

If this helps.

On displacement boats the maximum speed is governed by wave making and as soon as the stern drops into the trough of the bow wave the hull will simply not go any faster, you just burn more fuel making ever bigger waves. Also water resistance goes up by the square of the speed so doubling the speed increases the water resistance by four.

I have put your length (21 ft as the waterline length) into formula for maximum hull speed for displacement craft using 1.2 as the hull constant ( we do not know what your hull constant is but about 1.2 to 1.3 is unlikely to be far off the mark). This gives a maximum hull speed of just over 5 knots (5.7 mph). This is in free open water, it will be  worse the more restricted the channel.

Because we do not know your hull constant I suspect that you might be over driving the boat and wasting fuel.

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Crow    12

Tony ,I think your right, to many years on piece work hasn't helped ,every thing I do seems to be at full chat,I'm just going to slow everything down,Chesterfield canal next sat for a week so that will definitely slow things up,it should be running on fumes or the vapours  of a oiley rag ,nick

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