perkins M30 idle

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dan8152

dan8152

.
May 26, 2013
45
catalina c22 C30TR Winthrop Harbor Marina
I have a new to me catalina 30 with a perkins 30hp engine and trying to figure out what the idle should be. the mid setting on the throttle is about 1200rpm and that is what the PO used as idle. It goes lower though and the surveyor said it should be quite low. When under 1200rpm the charging warning light comes on though and the idle is rough (boat has 4 batteries and large alternator).

I'm not liking having to coast a lot when docking as at 1200rmp its doing over 3knts. I have to shift in and out of gear to come in slow. The owners manual just says min idle speed 900rpm


thanks for any information
 
Bill Roosa

Bill Roosa

.
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
I'd not worry about the alternator charging below 1200 RPM. a 30 HP P should idle at 800ish RPM or lower. If your alternator / crankshaft pulley ratio is wrong then you will get alternator alarms. No worries as you will not be doing that much and the battery bank "should" be able to supply the power in those situations. I'd not try and "dock the boat for 3 hours" and don't thing that is the issue. Typical pulley ratios are 3:1 so check that. If you have the right ratios then the regulator is suspect. In all cases it is not a problem that would keep me from (really) "idling" the motor to dock the boat. If she will not idle (800ish RPM) then there is a problem
 
dan8152

dan8152

.
May 26, 2013
45
catalina c22 C30TR Winthrop Harbor Marina
Bill Roosa said:
I'd not worry about the alternator charging below 1200 RPM. a 30 HP P should idle at 800ish RPM or lower. If your alternator / crankshaft pulley ratio is wrong then you will get alternator alarms. No worries as you will not be doing that much and the battery bank "should" be able to supply the power in those situations. I'd not try and "dock the boat for 3 hours" and don't thing that is the issue. Typical pulley ratios are 3:1 so check that. If you have the right ratios then the regulator is suspect. In all cases it is not a problem that would keep me from (really) "idling" the motor to dock the boat. If she will not idle (800ish RPM) then there is a problem
Click to expand

thanks so much for the response! I did find the engine owners manual and it said "MIN idle 900rpm" that sounds a bit high I'll double check the model and the manual when I get home from work.
 
Bill Roosa

Bill Roosa

.
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
If the manual is saying 900 then go with that.
 
dan8152

dan8152

.
May 26, 2013
45
catalina c22 C30TR Winthrop Harbor Marina
Bill Roosa said:
If the manual is saying 900 then go with that.
Click to expand
I also noticed that its a perama m30 and the PO had the idle at 1500 not 1200. It sounds great at1000 though some vibration at 900.
 
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