[Sentoa] Fuel usage Cummins 330

[David Cheyette]

I'm not on the boat right now, but I'll check out the speed differential
between 1500 & 1750 next time out - this makes sense.  Thanks for those
answers, very helpful.

David Cheyette
Maisy 37-100
Seattle, WA 

-----Original Message-----
From: sentoa-bounces at lists.samurai.com
[mailto:sentoa-bounces at lists.samurai.com] On Behalf Of Irwin "Scotty"
Scott
Sent: Tuesday, June 16, 2009 9:44 AM
To: 'South East Nordic Tugs Owners' Association (SENTOA)'
Subject: Re: [Sentoa] Fuel usage Cummins 330

Hi All,

I've received a couple of emails requesting the chart as an .xls file.
I don't know if this list will allow attachments or not but I'll give it
a try.  If not, I've posted it on my server:
www.irscott.net/temp/nt_37_fuel_burn.xls

To respond to David's questions:

1.  The rpm, gpm, and speed numbers were taken from the sea trial report
for my boat, an early 2002 NT 37 (37-063).  The other numbers were
calculated based on that data.  I just noticed that the Range numbers
were off on my posting.  They've been corrected on the attached
spreadsheet.

2.  Statistics don't lie, but....  I've been led to understand that
1,750 is the engine speed for the boat to reach hull speed.  If this is
correct, I find it plausible that an inefficiency would precede that
point.  If this assumption is correct, your observation would highlight
it.  Keep in mind that I'm high on common sense but low on education.
I'm interested on hearing other opinions on this.

3.  We'll have to hear from Jim on this query.  It'll be interesting to
see the differences.

I found it interesting at WOT the fuel burn was the highest, but the mpg
was better than the next lower engine speed.

If others have their rpm, gpm, mpg sea trial data it would be
interesting to see it in order for everyone to make comparisons.  It
would be even more interesting if anyone with a Flo-Scan has this
information on an engine with over 1,000 hours and the boat in use and
real-life condition.

Irwin "Scotty" Scott
Three Jeans (NT 37-063)
Concord, CA



-----Original Message-----
From: sentoa-bounces at lists.samurai.com
[mailto:sentoa-bounces at lists.samurai.com] On Behalf Of David Cheyette
Sent: Tuesday, June 16, 2009 8:50 AM
To: South East Nordic Tugs Owners' Association (SENTOA)
Subject: Re: [Sentoa] Fuel usage Cummins 330

I am curious about several items:

1. What is the source of the table? (single boat, NT, Cummins?)

2. I wonder why the difference of 250 RPM only gives .1 knot (1500-1750)
- seems wrong to me - and doesn't work that way on my 330...

3. Where is the table that Jim referred to for the common rail version

Thanks,

David Cheyette
Maisy 37-100
Seattle, WA