On Mon, 26 Nov 2007 19:36:09 -0500, Wayne.B
wrote:

On Mon, 26 Nov 2007 23:03:52 +0700, Bruce in Bangkok
wrote:

Interesting. Have you tried other fractions of "hull speed" to see if
the same ratio of one engine fuel consumption to twin engine
consumption remains the same?

I have tried 1.0SQRT(LWL) and 1.1 - as Beebe and others predict, 1.0
is more efficient. 1.0 is about as slow as I'm willing to go, and
then only over longer distances where I'm already committed to running
day and night.

As an aside all 6-71's weren't rated at the same power and one of the
differences was the injector s. They came with different colored tags
as I remember. If you are interested in improving fuel economy (and
losing horse power) talk to an experienced Detroit diesel mechanic
about changing injectors. It might give you a bit better economy, if
you are interested.

Yes, I've considered replacing the injectors and may do it at some
point.

Injector N55, Fuel Output Min.24 - Max.30
''''''' N60 "''''''''''''' 30 - '' 36
'''''''' N65 ''''''''''''''' 40 - '' 46
'''''''' N70 ''''''''''''''' 38 - '' 44
'''''''' N80 ''''''''''''''' 44 - " 50

I believe that I have the N80s at this point, so in theory I could go
all the way down to N55s. That would clearly reduce power and torque
but it's not obvious what the impact on economy would be. It could
also have an adverse impact on the present reduction gear ratio and
prop pitch.


True, but this raises the question of whether you are actually
developing " X" amount of horsepower at "Y" RPM. I assumed from a
previous post that you were calculating H.P. from fuel consumption
figures which is really just a ballpark calculation.

Given that the 71 series are no longer made what are rebuilt injector
prices like? Or have they gone out of sight because a lot of people
would rather have the old all mechanical engines then the new
electronic models?


Bruce-in-Bangkok
(Note:remove underscores
from address for reply)