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Old 08 September 2011, 20:34   #1
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Mercury 6hp Fourstroke WOT fuel....

...consumption.

Anyone know what it is?
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Old 09 September 2011, 05:23   #2
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Working hard as an aux or on a small tender? I don't think they reach anywhere near max revs when they are pushing a rib along as an aux.

Not exactly what you wanted but I was motoring on my Merc 4hp aux for a while the other day (I use about 3/4 throttle as the rest just seems to add noise rather than speed) and took a very rough observation of fuel use for future reference, it used about 1/2 of the approx 1L tank in about 20 min doing about 4 knots. I reckoned a full tank would give roughly 45min endurance pushing the Vipermax.

Must carry my 12L portable tank more often...
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Old 09 September 2011, 05:55   #3
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...consumption.

Anyone know what it is?
I have the same engine, i believe made by tohatsu???

Here are NISSAN/TOHATSU consumption charts:

Nissan Marine Outboards - Authorized Distributor Offering Boat Motor Products, Technical Information, & Dealer Locations for the U.S. & Canada."

For a merc 6 at WOT you are looking at about 2L/hour at 5500 revs.

My 20hp twatshzu burns 6.2 l/hour at WOT, apparently. This is a lot when you pay £1.50 per L on the west coast of Scotland!
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Old 09 September 2011, 08:26   #4
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.
My 20hp twatshzu burns 6.2 l/hour at WOT, apparently. This is a lot when you pay £1.50 per L on the west coast of Scotland!
Would you like to borrow my SIB's bigger brother? Burns 65l/h at WOT
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Old 09 September 2011, 08:29   #5
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Working hard as an aux or on a small tender? I don't think they reach anywhere near max revs when they are pushing a rib along as an aux.
It'll be on the tender Steve. I was wanting worst case sernario and was wondering roughly how much time I could spend on the water for a given amount of fuel.
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Old 09 September 2011, 09:05   #6
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Would you like to borrow my SIB's bigger brother? Burns 65l/h at WOT
Oh lordy!


Would love to - assuming, of course, that it comes with free petrol vouchers???? Is that correct??

Kind of happy i only have a 3.8M sib and a 20hp engine!
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Old 09 September 2011, 16:35   #7
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Approx 1.6 ltrs an hour at wide open throttle.
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Old 09 September 2011, 16:44   #8
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Thanks TD
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Old 13 September 2011, 16:23   #9
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Would you like to borrow my SIB's bigger brother? Burns 65l/h at WOT
Very surprised at that! At WOT we burn over 100lph certifiable by a number of members on here

65lph would be a normal heavy load high(er) speed cruise figure but of course that doesn't tell the whole economy story.
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Old 13 September 2011, 16:54   #10
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Very surprised at that! At WOT we burn over 100lph certifiable by a number of members on here

65lph would be a normal heavy load high(er) speed cruise figure but of course that doesn't tell the whole economy story.
And what size of outboard do you have sitting on the transom of your Vipermax?
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Old 14 September 2011, 04:07   #11
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Well there is a simple calculation thats used to work out the approx fuel consumption.
For a conventional 2 stroke its a third of the HP at wide open throttle per hour.
For a Four stroke/DFI you take a third off that figure again.
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Old 14 September 2011, 10:13   #12
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12miles pushing a 400KG Drascombe roughly 5 litres on 1/4 throttle Honda 4 stroke
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Old 14 September 2011, 12:18   #13
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Well there is a simple calculation thats used to work out the approx fuel consumption.
For a conventional 2 stroke its a third of the HP at wide open throttle per hour.
For a Four stroke/DFI you take a third off that figure again.
I wish it were.

That would make my 150 DI, 35 l/h at WOT

I have a fuel flow gauge which is pretty accurate (5% overestimation) and that reads 65l/h at WOT
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Old 14 September 2011, 15:28   #14
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33.4ltrs actually!!
Its a approximate calculation that Merc/Mariner use. Every boat is different depending on weight etc.
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Old 14 September 2011, 15:45   #15
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So I guess that the fact I burn 65l/h in real terms means this calculation isn't all that "rule of thumb" then?
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Old 15 September 2011, 19:39   #16
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Highest I have seen on my Etec at WOT or very nearly that is 56lph so the thumbs are quite variable in length
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Old 16 September 2011, 06:47   #17
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I like Turbodiesels thumbs Then it's back to reality
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Old 17 September 2011, 07:12   #18
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Well i guess Etec's break the rules for Economy then. I thought they were supposed to be good on fuel.
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Old 17 September 2011, 17:53   #19
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Good until you use full moo I guess

Mine does consistently 1.1 - 1.2 nm/ltr in the cruising range 25-30 knots, but I think that drops to 0.7 ish when you get close to WOT. To be honest on the odd occasions I get to that speed I'm usually too busy holding on to be peering at ickle writing on the iCommands
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