Please don't laugh at me....

Status
Not open for further replies.
cymeyer

cymeyer

.
Jul 8, 2005
522
Jeanneau 389 Grosse Pointe Farms, MI
We have had a 321 for about 14 years and love the boat. Have not done any cruising and had never left Lake St Clair with our boat.
This weekend, we ventured out. We motored up the St Clair River and for the next 3 days we will be in Lake Huron, a huge Great Lake.

So when motoring (which we have not done much with), what is the best RPM? I remember reading a thread on this but could not find it. We motored at about 2600 RPM which was about 6.6 knts. Seemed good to us, but was not sure.

What is the best RPM for motoring for 8 hours?

Sorry for the stupid question....
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
Usually about 75-80% of WOT. Other thing is if you're going to motor for that long, change the rpms regularly. Like every 1/2 hour.
 
Stu Jackson

Stu Jackson

.
Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
'Cuz that's what a lot of diesel engine manuals suggest: don't run at the same rpm for extended times.
 
W

wufibugs

.
Aug 16, 2009
1,000
Hunter 1986 H31 California Yacht Marina, Chula Vista, CA
Cute, Stu, but I learned long ago not to question the soundness of your suggestions. What I was wondering was what might happen if you don't do the oscillating rpm thing?
 
J

Joe2954

.
Jan 22, 2008
169
Beneteau 343 Saint Helens, Oregon OR
I find an rpm that sounds good - nothing rattling, engine not straining etc about 70-80% wot. For my 3ym30 that's about 26-2800 rpm. A few rpm can sometimes make a big difference in what rattles.
Drop to 2000 in no wake zones. Push it up to wot for a few minutes every hour, drop down to idle when I need to use the head and let Otto drive.
Diesel generators run at a constant rpm, so I've never worried too much about ridges in the cylinders after breakin. Carbon in the exhaust elbow can be a problem for some engines thus the wot. I probably don't run it wot enough.
Long runs cause my alternator to heat up and shut itself off unless I run an exhaust fan that is noisy. I found I can open an inspection hole and remove the aft access hatch to the engine to keep it cool. Heats up the aft cabin though.

Joe
 
Status
Not open for further replies.

Top Bottom