Hours per litre of a Yanmar 2GM20!

[Zagato]

Just interested to see if mine is about right as my fuel gauge is stuck.

Mine did 24 Litres in 30 hours from the last fill - pretty frugal I think

 

[Georgio]

Depends on RPM but that could be spot on, I have the same engine and at low RPM is sips diesel.

 

[Georgio]

http://www.simplicity-marine.com/pdf/Yanmar/123 GM INBOARD.pdf

1L/hr at 2000 RPM

 

[Tranona]

Consumption is a function of power used, rather than revs. Typical fuel consumption on that size engine would be about 1.25l an hour - which is roughly what you are getting. Your boat should be propped so that the cruising speed is at around 2600 and maximum around 3400.

 

[maby]

Consumption is a function of power used, rather than revs. Typical fuel consumption on that size engine would be about 1.25l an hour - which is roughly what you are getting. Your boat should be propped so that the cruising speed is at around 2600 and maximum around 3400.

Do the sums again - he's reporting 0.8l per hour - seems a bit low to me - more like what we used to get out of a 1GM10 - but it is very dependent on the type of boat and style of usage. I never did the sums in detail, but I think our delivery crew probably managed little more than 2l per hour with a 55hp Yanmar on a 43 foot boat.

 

[NDG]

We get about 0.75 to 1 litre per hour on our 2GM, about the same as you.

 

[Zagato]

Thanks for that I can now gestimate how much is in the tank. I don't use it hard, probably mid revs most of the time as I tend to go with the tides apart from a few port entrances like Poole that needed a bit of go over a longer period.

It maybe more like .9 - 1L per hour also as I did top it up a few times this time around as the diesel does throth up quite bit.

 

[onesea]

I recon on 1.5 ltrs an hour but:
1) I boat is 35 foot
2) That allows me a little in hand in fuel calculations (I think)
3) I have never properly measured it.
4) I hate listening to engines so I am prone to running it a little hard...

 

[Tranona]

Yes you are right - I transposed the figures in my faulty mental arithmetic! If he is getting that low a consumption he is probably running the engine too slow. As you say that is 1GM type consumption.

 

[stuey_two]

I seem to remember a rule of thumb was 1litre/hr/10hp. Look up the power output of your engine at your usual cruising rpm and do the sum.
The rule works for my nanni 21hp

 

[Twister_Ken]

I seem to remember a rule of thumb was 1litre/hr/10hp. Look up the power output of your engine at your usual cruising rpm and do the sum.
The rule works for my nanni 21hp

And for my 3YM20.

 

[Spyro]

20l in 14 hours for me at 5.5knts average, flat sea 32 ft boat.

 

[vyv_cox]

I think the litre/hr/10 HP has more to do with the power being used than what is installed. My 3GM30 driving a 35 ft boat has averaged 1.5 litres per hour over the past seven years, more than 1500 hours of motoring. Considerably less than the guideline would suggest. I also assume it has a lot to do with the slipperiness of the hull being driven.

 

[snowleopard]

I seem to remember a rule of thumb was 1litre/hr/10hp. Look up the power output of your engine at your usual cruising rpm and do the sum.
The rule works for my nanni 21hp

My 3GMs use 2.5 l/hr at 2700 rpm which agrees pretty closely. OTOH at 1700 it's less than 1 l/hr

This graph is a typical consumption profile:

 

[Sybarite]

Feeling 9m20; 3.8 tonnes; 31' long; 18hp Volvo; 2300rpm; 1.5 l/hr @ 6 knts.

6 knots is a good cruising speed = 1 mile every ten minutes.

 

[Sybarite]

My 3GMs use 2.5 l/hr at 2700 rpm which agrees pretty closely. OTOH at 1700 it's less than 1 l/hr

This graph is a typical consumption profile:

Your graph could do with including boat speed at different rpm settings.

 

[MM5AHO]

At about 2000 rpm = 5knots (Rival 32) we use just under 1 litre per hour.

 

[lw395]

Your graph could do with including boat speed at different rpm settings.

+1.
I've found it to vary hugely, a lot of fuel if motoring against tide wind and chop, surprisingly little if motorsailing and the sails are contributing most of the time.
On a 32ft boat, the engine is doing a lot more work at 5.5knots than 5. At 4.5 knots on flat water, very little work at all.