CapnWill and all;
Thanks, CapnWill, for the engine data. It was interesting. There is one other
source of valuable engine performance that is available. It is the Propeller
Law Curve and is available from most engine manufacturers, such as Cummins.
Cummins calls it a Marine Performance Curve. It more accurately portrays how
horsepower and fuel consumption relates to RPM using a "typical" propeller
and allows for normal transmission losses. Cummins sent me a copy for the
6BT5.9M engines I have. They went so far as to Fed Ex it to me! Can't beat
that. The accuracy of these curves relative to a specific boat usually is
dependent upon how well matched the wheel is to the engine and boat as a
unit. Past experience with these curves have proven them to be quite
accurate. I have not had the opportunity to check the Cummin's Marine
Performance Curve against our Albin 43 and its Cummins 210's, but it will
give a very good estimate at any rate. The Marine Performance Curve that
Cummins sent to me does not exactly coincide with the data in the Operation
and Maintenance Manual for these engines, as the data in the manual is more
generic.
Usually, the Propellor Law Curve data is included with other performance
graphs for marine engines so it is just a matter of picking out the right
curve. Be sure to read all the notes to fully understand what the graphs are
telling you.
Caterpillar marine performance curves for current production engines are
available on the Internet and can be downloaded and printed. These might not
be accurate for older engines though.
If these curves are requested from an engine manufacturer, they will probably
want the same data Cummins did; complete model number, serial number and date
of manufacture, to be sure they are providing the correct data.
Wayne
M/V Celestial
Albin 43
CapnWill and all;
Thanks, CapnWill, for the engine data. It was interesting. There is one other
source of valuable engine performance that is available. It is the Propeller
Law Curve and is available from most engine manufacturers, such as Cummins.
Cummins calls it a Marine Performance Curve. It more accurately portrays how
horsepower and fuel consumption relates to RPM using a "typical" propeller
and allows for normal transmission losses. Cummins sent me a copy for the
6BT5.9M engines I have. They went so far as to Fed Ex it to me! Can't beat
that. The accuracy of these curves relative to a specific boat usually is
dependent upon how well matched the wheel is to the engine and boat as a
unit. Past experience with these curves have proven them to be quite
accurate. I have not had the opportunity to check the Cummin's Marine
Performance Curve against our Albin 43 and its Cummins 210's, but it will
give a very good estimate at any rate. The Marine Performance Curve that
Cummins sent to me does not exactly coincide with the data in the Operation
and Maintenance Manual for these engines, as the data in the manual is more
generic.
Usually, the Propellor Law Curve data is included with other performance
graphs for marine engines so it is just a matter of picking out the right
curve. Be sure to read all the notes to fully understand what the graphs are
telling you.
Caterpillar marine performance curves for current production engines are
available on the Internet and can be downloaded and printed. These might not
be accurate for older engines though.
If these curves are requested from an engine manufacturer, they will probably
want the same data Cummins did; complete model number, serial number and date
of manufacture, to be sure they are providing the correct data.
Wayne
M/V Celestial
Albin 43
