Looking for real life fuel usage on 2006ish Azimut 46 CAT C9 and Azimut 50 CAT C12

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HelloBoat

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Hi,

Does anyone have either a 2006ish Azimut 46 or Azimut 50 and is willing to share actual fuel consumption data?

I am looking around 2005/2006 models where the Azimut 46 would have CAT C9 575hp engines and the Azimut 50 would have CAT C12 670hp.

Any feedback is much appreciated :-)

Thanks!
 
Your C12 will be 180/200 L/ hr at cruise planing .
I,am using my fuel data from MAN 12.8 L ,6 cylinders of 700 Hp .

There’s some specific energy burn / Kg of fuel per Hp constant s .Does not matter where the 670 or 700 horses come from ,nor the name on the cam rocker box , be it a Volvo D12 , CAT C12 or MAN 12..8 L —— they burn basically the same .

Guessing the C9 s proportionally less 140/160 L / r

Theses are for a pair .
Speeds depend what they are in .

Here you are @1900 rpm ( tap on the image to enlarge ) that’s just the port engine , so 2x that
View attachment 73077
 
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Portofino said:
Your C12 will be 180/200 L/ hr at cruise planing .
I,am using my fuel data from MAN 12.8 L ,6 cylinders of 700 Hp .

There’s some specific energy burn / Kg of fuel per Hp constant s .Does not matter where the 670 or 700 horses come from ,nor the name on the cam rocker box , be it a Volvo D12 , CAT C12 or MAN 12..8 L —— they burn basically the same .

Guessing the C9 s proportionally less 140/160 L / r

Theses are for a pair .
Speeds depend what they are in .

Here you are @1900 rpm ( tap on the image to enlarge ) that’s just the port engine , so 2x that
View attachment 73077
Click to expand...

Thank you as always sir :-)
What speed are you doing at 1900rpm? I am guessing 27kn'ish?
 
Portofino said:
Revisit the pic and see the gps readout at the bottom of the plotter .
Click to expand...

Sorry, overlooked that. Thanks for sharing the info!
One last question, I have seen a post from you on VP D12-675 engines some time ago that you cruised around 1550rpm at 25kn using 70L per side. Was that with this engine as well?
 
HelloBoat said:
Sorry, overlooked that. Thanks for sharing the info!
One last question, I have seen a post from you on VP D12-675 engines some time ago that you cruised around 1550rpm at 25kn using 70L per side. Was that with this engine as well?
Click to expand...

Portofino’s boat is quite a different beast to any of the four FB boats you are considering.
His is a 40ft (ish) open high performance sports boat. The Azimut and Fairkine models you are looking at are considerably heavier so while his fuel consumption is a good yardstick load on his engines at a given rpm (except right at the top) is likely to be less therefore fuel burn a little lighter.

We have a 50ft boat running twin 550Hp engines but she’s much older than the boats you are looking at.
We trip plan on 0.5mpg if planing, 1.3mpg if plodding at hull displacement speed.

Pretty much though if you need 300hp to move at a given speed a Diesel engine will use pretty much the same fuel, assuming the engine is in good condition with no faults. I’d expect a boat with modern engines and lighter build to do a little better than ours hence my estimate of 0.7-0.8mpg
 
HelloBoat said:
Sorry, overlooked that. Thanks for sharing the info!
One last question, I have seen a post from you on VP D12-675 engines some time ago that you cruised around 1550rpm at 25kn using 70L per side. Was that with this engine as well?
Click to expand...

Yes
Recently I’ve been cruising in company and reducing further to around mid 1400 , to adjust to my mates 22 knot cruise .
It doesn’t feel right ,was not intended for this as there’s hardly any turbo boost registering and the EGTs are waaaaay low .

But I doubt the 50 FB ,s with 12 L engines that you are prospecting have the breadth of rpm range and still be able to plane as this boat .
Jez ^^^ has explained why .

You are gonna be doing north of 1750 maybe even over 2000 rpm ( if wot is 2300 or higher ) to get anywhere near 25 knots .Thats why I suggested figure on 200 L / h or a bit less if the boat can take less rpm and stay up .

As said D speed is completely different and completely slower passage planning as well of course .
Eg 825 / 875 rpm give me just under 20 L/h each ,so 40 in all for just over 9 knots ,
1st click tickover 600rpm is over 6 knots .

The various weights and in some respects hull forms of boats with 12 L lumps fitted translates into different amounts drag ,for the given hps of circa 700 Hp .
Hence the different speeds they all go ,but the fuel burns in L/ hrremains more / less the same .

How ever I might arrive earlier and switch off sooner thus mpg can be misleading that’s why I use L/hr .
What you do in that time say an hour ,or how far you go determines you total burn for the day .

Slowing down may look better on the L/ hr delta ,but you take longer thus the extra time running eats up any perceived saving .

As per another thread I just ( sea state permitting- usually plays ball:encouragement:) just set them at 80 % load which is a little lower rpm ( when the sterngear is clean ) say 1800 rpm and burn 90 L/hr per side running @28 knots ish ?
I feel that’s what the boat was designed and optimised for .

I just accept the fuel bills as is so to speak and don,t try and find a ultra eco running solution as I think unless @ D speed there isn,t one .

Done about 60 hrs this summer and it ain’t over yet in the SoF .
 
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You are looking at around 6.5 to 7 liters per mile on both the fifty footers you are looking and six liters per mile with the Azimut 46 and Fairline 46 Phantom.
The Fairline 46 Phantom with Tamd75 should be around 5.5 liter per nm at its cruise of around 22/23 knots.
 
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