Bukh DV20 fuel consumption

Carib

Carib

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www.sailinginlimbo.blogspot.com
What should approximate fuel consumption for a Bukh DV20 look like? Our cruising revs are in the region of 1500 - 2000. Just working out how much we might need to use cross-channel if there's no wind..

Much appreciated!
 
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There is a rule of thumb for any constant running diesel (ie, not a vehicle) is each 10hp uses 1 litre per hour,
We have the slightly more powerful DV24 based on the same engine and cruise at around 2000 rpm. I assume we use 2.5L an hour doing 5.5 knots to cover 70nm, which means we use around 32 liters to cross from Chichester Bar to Cherbourg, about 1/3 of our tank. In reality I think we use less but cant say exactly how much less.
 
Carib said:
What should approximate fuel consumption for a Bukh DV20 look like? Our cruising revs are in the region of 1500 - 2000. Just working out how much we might need to use cross-channel if there's no wind..

Much appreciated!
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Wow, is it a gas turbine.:D

I think you have a Samphire, we had a Southerly 95 for years and tended to average about 5.6 -5.7 knots on motor.

I have fuel consumption for later years when we only did about 500nm per season and it was in the 1.2 - 1.6 litres per hour between 2005 - 2009. I don't have figures to hand for earlier years but might be able to find them. We had the same boat for about 24 years.

I would imagine the Samphire would be lighter but the Southerly 95 was a very easily driven hull. 1.6-1.8 litres per hour might not be far away.
 
Mistroma said:
I think you have a Samphire, we had a Southerly 95 for years and tended to average about 5.6 -5.7 knots on motor.
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No longer - I must remove that link or update it. I have a Rustler 31 now . Assume these numbers are for a Bukh? That sounds about right. [Yes - I edited my post to correct the ambitious RPM!]

seumask said:
There is a rule of thumb for any constant running diesel (ie, not a vehicle) is each 10hp uses 1 litre per hour,
We have the slightly more powerful DV24 based on the same engine and cruise at around 2000 rpm. I assume we use 2.5L an hour doing 5.5 knots to cover 70nm, which means we use around 32 liters to cross from Chichester Bar to Cherbourg, about 1/3 of our tank. In reality I think we use less but cant say exactly how much less.
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That's helpful thanks - rules of thumb always good!
 
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Carib said:
No longer - I must remove that link or update it. I have a Rustler 31 now . Assume these numbers are for a Bukh? That sounds about right. [Yes - I edited my post to correct the ambitious RPM!]


That's helpful thanks - rules of thumb always good!
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We probably covered about 20,000 miles in that boat. Figures quoted were for doddling around the West Coast of Scotland when we only did about 500nm per season. Pre-2000 trips tended to be longer, sometimes round trip up East coast through to West and cruises from Forth to Belgium, Holland as far as Germany. I could probably dig out figures for those trips but information you have is probably good enough for a short cross-channel trip. I'm guessing 70-75 nm and 20 - 25 litres would be about right unless you are motoring straight into foul weather.

I assume that, like most of us, you will be trying to leave with a good weather window.:D
 
On our Sadler 32 with the Bukh 20 I used to plan at 1/2 gallon an hour at 6 knots, but used a lot less at 5.

Folding prop.

We fitted the allegedly more efficient Bukh 24 just before lockdown. Yet to have a fill up this year...
 
I think the 1 litre per 10 HP assumes that all of the 10 HP are being used. In cruising mode this is unlikely to be the case. We replaced a Bukh 20 with a Yanmar 3GM30F that has consumed 1.5 litres per hour measured over the past 10 years. I never measured the consumption of the Bukh but since we cruise at about the same speed in the same boat I assume the consumption of the Bukh was not a lot different. Sadler 34, Bruntons 2-blade feathering prop.
 
I've been logging fuel consumption for the DV20 on our Westerly Merlin (3-blade fixed prop) for the 4+ years we've had the boat. It very consistently uses between 1.3 and 1.4 litres per hour. That's calculated each time I fill up, so it is an average over a variety of running conditions. Steve
 
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Carib said:
What should approximate fuel consumption for a Bukh DV20 look like? Our cruising revs are in the region of 1500 - 2000. Just working out how much we might need to use cross-channel if there's no wind..

Much appreciated!
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If you keep to 2k revs you will not use more than 2.5l per hour. But in the event of having to rev up and push against adverse conditions, usage runs up quickly - even 3.5l per hour. Plan accordingly.

PWG
 
vyv_cox said:
I think the 1 litre per 10 HP assumes that all of the 10 HP are being used. In cruising mode this is unlikely to be the case. We replaced a Bukh 20 with a Yanmar 3GM30F that has consumed 1.5 litres per hour measured over the past 10 years. I never measured the consumption of the Bukh but since we cruise at about the same speed in the same boat I assume the consumption of the Bukh was not a lot different. Sadler 34, Bruntons 2-blade feathering prop.
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Are diesels around the 0.25 to 0.3 litres per kwH mark? which would be around 0.2 litres per HP.hr?
That's power actually used, not the nominal max power of the engine.

I've always found fuel consumption to be less than expected in flat water and remarkably more than expected bashing into wind and waves.
A clean bottom and slow enough not to make waves doesn't need much power when it's calm.
 
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