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Old November 11th 05, 07:07 AM
Bill Kiene
 
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Default Help with fuel consumption?

Hi All,

A fishing buddy has a 17.5' Crestliner walk through aluminum boat with a
Volvo 3.0 GS (4 cylinder 120 hp) I/O.

It goes 30 mph @ 4000 rpm and top speed is 39 mph.

What should his fuel consumption be for this boat while cruising @ 30 mph?

He is wondering if his boat is consuming more fuel than it should be.

Thanks for any help.

-
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA

Web site: www.kiene.com




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Old November 11th 05, 12:35 PM
Dr. Dr. Smithers
 
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Default Help with fuel consumption?

Bill,

This is a fairly light boat, 4000 rpm might not be the most fuel efficient
cruising speed. The boat will probably plane at 3000 rpm. I had a Volvo 6
cyl. a few years back, and the best mpg was at 3600 rpm.

Your buddy can buy a Floscan fuel meter for about $300, or he might be able
to borrow one at his local marina mechanic. This will give his boat's best
mpg and gph.


"Bill Kiene" wrote in message
om...
Hi All,

A fishing buddy has a 17.5' Crestliner walk through aluminum boat with a
Volvo 3.0 GS (4 cylinder 120 hp) I/O.

It goes 30 mph @ 4000 rpm and top speed is 39 mph.

What should his fuel consumption be for this boat while cruising @ 30 mph?

He is wondering if his boat is consuming more fuel than it should be.

Thanks for any help.

-
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA

Web site: www.kiene.com





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Old November 11th 05, 12:58 PM
 
Posts: n/a
Default Help with fuel consumption?


Bill Kiene wrote:
Hi All,

A fishing buddy has a 17.5' Crestliner walk through aluminum boat with a
Volvo 3.0 GS (4 cylinder 120 hp) I/O.

It goes 30 mph @ 4000 rpm and top speed is 39 mph.

What should his fuel consumption be for this boat while cruising @ 30 mph?

He is wondering if his boat is consuming more fuel than it should be.

Thanks for any help.

-
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA

Web site: www.kiene.com



The two most efficient speeds for a planing hull are

1) the point at which it rises over the bow wave and is "on plane"
2) dead slow.

A wild guess is that your friend's boat might get roughly double the
nmpg at 30 that it realizes at 40. If you check the fuel consumption
chart for most engines, the curve gets extremely steep in the last
15-20% of the RPM range. If he's running at WOT to make that 40, he's
also spending a lot of money that's invisible (for now) on additional
maintenance and a premature rebuild.

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Old November 11th 05, 03:53 PM
Lloyd Sumpter
 
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Default Help with fuel consumption?

On Fri, 11 Nov 2005 07:07:55 +0000, Bill Kiene wrote:

Hi All,

A fishing buddy has a 17.5' Crestliner walk through aluminum boat with a
Volvo 3.0 GS (4 cylinder 120 hp) I/O.

It goes 30 mph @ 4000 rpm and top speed is 39 mph.

What should his fuel consumption be for this boat while cruising @ 30 mph?

He is wondering if his boat is consuming more fuel than it should be.

Thanks for any help.


Hmmm... most replies don't seem to be addressing the question: ie what
SHOULD his fuel consumption be (not "how to improve fuel consumption").

I'll take a Wild Stab: I had an 18ft Campion with a 120hp 4-cyl
Mercruiser. It was quite a bit heavier that yours, had a top end around
30mph iirc. And iirc (it was a few years ago) I got about 4-5mpg at
cruise (20-25mph). I'd guess you should be getting around 5 or so.

Does this help?
Lloyd Sumpter
"Far Cove" Catalina 36

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Old November 11th 05, 04:44 PM
Bill Kiene
 
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Default Help with fuel consumption?

Thanks for the help.

--
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA

Web site: www.kiene.com


"Bill Kiene" wrote in message
om...
Hi All,

A fishing buddy has a 17.5' Crestliner walk through aluminum boat with a
Volvo 3.0 GS (4 cylinder 120 hp) I/O.

It goes 30 mph @ 4000 rpm and top speed is 39 mph.

What should his fuel consumption be for this boat while cruising @ 30 mph?

He is wondering if his boat is consuming more fuel than it should be.

Thanks for any help.

-
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA

Web site: www.kiene.com







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