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Old 11 February 2013, 19:53   #11
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Is any one outboard inherently more economical than another? that's what I should have asked first.

I want to take the hull out of the equation. I don't care what hull, I want the engine tests to be on the same hull, don't care what. Any boat, any hull, if you take two of them and try the different engines on the two what kind of variation might you see?

The makers tech bulletins are great but what I want is for them to use the same boats so we can eliminate the hull from the equation.

It would be safe to narrow it down to 4 strokes.

How crazy do I have to get deciding what engine I get?

Jason
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Old 12 February 2013, 05:01   #12
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Problem is you can't take the hull out the equation!

With boats there are so many variables (e.g I bought a used engine for my Rib, and after one trip I needed to up the prop pitch by 3" to stop the engine killing itself by over revving - it was pushing a small cabin cruiser along in it's previous life. - The "unmeasurable" factror in this was the previous engine was a long stroke 2 Cyl of almost equal horsepower. Sounded great when you opened the throttle & let it sing at WOT, but after a couple of hours of cruise downing speed by 4 knots & running it at 3/4 throttle was a lot less grating on the eardrums. the "new" 3 Cyl goes "quiet" at not far off WOT, so I tend to crusie now around 1000 rpm higher than the old machine....

There really are a LOT of factors in real world fuel economy.

The only "general" one you can safely say is that a modern 4 - stroke will drink less than an oldschool 2- stroke IF you do a LOT of low speed / close to idle throttle boating.


FWIW I get 0.83L / Nautical mile out of a 30YO boat and a 25YO engine (0.96 Statute miles - yep, 1L/mile as a round number! )
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Old 12 February 2013, 05:42   #13
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Originally Posted by 9D280 View Post
Problem is you can't take the hull out the equation!
I think what the OP wants is for someone to take the all the 250hp outboards from the various manufacturers over the past 5 years or so and stick them, one by one, on the back of the same hull, run it for a bit at different speeds etc, and then tell him whether the most fuel efficient one is more than 10% more efficient than the least efficient one, and roughly what the spread is.

Given that no-one is going to actually perform this experiment the next best thing is for someone with experience of a wide variety of engines (i.e. not me) to give their opinion on whether the spread is likely to be greater than 10%.

Sorry if I have misinterpreted you Jason....
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Old 12 February 2013, 07:28   #14
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This subject comes up on here every now and again. I seem to remember someone posting a list of engines with stats, including fuel consumption figures, which came from a test done somewhere in Scandinavia (I think).

I think it was re posted in a similar thread not too long ago. Of course, I can't remember when or where, but it does exist.

If you have a lot of time, maybe the search function will find it for you?

PS Last year I got 1.56 nautical miles per litre. 5.3m RIB Honda 90. Cruising speed 23-25 knots.
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Old 12 February 2013, 09:24   #15
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This subject comes up on here every now and again. I seem to remember someone posting a list of engines with stats, including fuel consumption figures, which came from a test done somewhere in Scandinavia (I think).

I think it was re posted in a similar thread not too long ago. Of course, I can't remember when or where, but it does exist.

If you have a lot of time, maybe the search function will find it for you?

PS Last year I got 1.56 nautical miles per litre. 5.3m RIB Honda 90. Cruising speed 23-25 knots.
Ah you West coast boys know how to squeeze the last drop!!

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Old 12 February 2013, 10:49   #16
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Yes, Clamchowder hit it right on the head.

We have the third highest gas prices here in CA, which I think are the highest un the US, so yes, squeeze everything I can. Now I know that is still nothing compared to the price in the rest of the world.

I did a search but it's kind of an ambiguous topic and I didn't run across it. I got lots of results.

Jason
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Old 12 February 2013, 11:12   #17
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Ah you West coast boys know how to squeeze the last drop!!

Sent from my iPhone using Rib.net
Put it through twice mate.

I was initially disappointed with the consumption (1.3mpl) of the new Honda - my old carbed Mercury 90 managed 1.6 mpl - but now the engine is loosening up it's doing much better. Really smooth and quiet now too. With a bit of luck it may get even better this year.

Cheers, Tony.
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Old 12 February 2013, 11:24   #18
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Originally Posted by Bigtalljv View Post
Yes, Clamchowder hit it right on the head.

We have the third highest gas prices here in CA, which I think are the highest un the US, so yes, squeeze everything I can. Now I know that is still nothing compared to the price in the rest of the world.

I did a search but it's kind of an ambiguous topic and I didn't run across it. I got lots of results.

Jason
I know this was a serious question, but sounds like you can't afford a boat in the first place... Or go less than WOT. Or get a smaller less powerful boat.

If you got the money for a 250hp you should NOT be whining about fuel costs. If you are, get a 175hp...
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Old 12 February 2013, 11:43   #19
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Yes, Clamchowder hit it right on the head.

We have the third highest gas prices here in CA, which I think are the highest un the US, so yes, squeeze everything I can

Well BooHoo Try paying 6 quid a gallon (around $9.50) admittedly that's for a proper gallon, not one of your piddly little US ones
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Old 12 February 2013, 11:53   #20
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Well BooHoo Try paying 6 quid a gallon (around $9.50) admittedly that's for a proper gallon, not one of your piddly little US ones
Aye!! the US gallon is 2 pints short...I don't know how the Yanks put up with that
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