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Old 04 April 2005, 08:43   #1
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Country: UK - Channel Islands
Town: Sark
Boat name: Braveheart 11
Make: Ocean
Length: 8m +
Engine: Outboard Twin 225 hp
Join Date: Mar 2005
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Yamaha 225 Four stroke

Can anybody help

I have a twin 225 Yammy four stroke installation on a 3 ton Rib. At first we burned between 4 and 7 miles per gallon. I was delighted. Gradually over a period of 18 months the consumption grew. Now it is at a miserable 1-2 miles per gal. I am very dissapointed.

The bottom is clean etc. Does anyone else have any similar experience with yammy 225 four strokes.

What technical areas can I have my engineers look at.
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Old 04 April 2005, 10:56   #2
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The fuel gauge, sounds like it reading correctly now, as I can't believe you ever got "4-7 miles per gallon" from a pair of 225's on a 3 ton rib!

Maybe the petrol fairy kept filling your tanks when you weren't looking!
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Old 04 April 2005, 11:13   #3
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Quote:
Originally Posted by Mike Doyle
......What technical areas can I have my engineers look at.
Your right hand Des
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Old 04 April 2005, 12:23   #4
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Engine: 44lbs of thrust....
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I'm with the Nobba on this one...... 1-2 "MPG" sounds about right... my much lighter boat with a single 250 4 stroke manages about 2.5 "MPG" so 1-2 has gotta be close....
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Old 04 April 2005, 12:31   #5
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I could believe 3mpgish on the basis of oh say cruise at 30kts burning 20lph per engine = 40 lph total or approx 9 gph gives 3 mpg. 4-7 must have been with a strong tide in your favour Anyway isn't petrol in the CI free or as near as damit makes no odd?!
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Old 04 April 2005, 14:07   #6
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Country: UK - England
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Is that all ???

Oh dear, my last boat, a 23' sports cruiser did 2.25 mpg cruising at 30 kts with an old 5.7 litre V8 Volvo + duoprop.

Surely the "modern" outboards can do better than this?

Whilst on the subject, I shall be taking delivery of a new RIB in May 2006 - Can't do this year - I am committed to major DIY between now and Christmas!

I am currently thinking of an 8 metre Humber with a 250 hp outboard and 70 gallon tank (plus a further 18 gallons in a reserve tank). But what 250 hp engine is likely to give me great performance and run on air? Well OK, a small amount of fuel then!

Should I be looking at the E-tec or a 4 stroke. If the latter, what seems to be the best at the moment? Alternatively, even if the E-tec uses the same amount of fuel as a 4-stroke, how much oil would I expect to use and at what cost?

I've been off the site for a few months, having cancelled a RIB last year, for medical reasons. But now I'm back

I look forward to hearing from you!

Cheers!

Chris.
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Old 04 April 2005, 14:46   #7
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Quote:
Originally Posted by Dirk Diggler
I can't believe you ever got "4-7 miles per gallon" from a pair of 225's on a 3 ton rib!
Me neither.

We reckon 5mpg as a rule of thumb with 1x 200hpdi on about 1.5 ton boat.
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Old 04 April 2005, 15:20   #8
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Quote:
Originally Posted by Jono
I'm with the Nobba on this one......
Watch it, or I'll send the boys up!
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