What is the recommended RPM?

[Bert]

Fellow Sailors,I reach my hull speed at about 2200 RPM with my 1982 Yanmar 3HM. The Yanmar specs don't provide the recommended cruising RPM and I hear that other folks run their Yanmar at 3400 to 3600 to keep their engine in shape. Does anybody know?Thanks folks.

 

[Steve Dion]

80-90% of max rated RPM.

Bert:The rule of thumb is 80-90% of the max rated RPM. If you engine is rated at 3600 max, then you should be running it at 2500-2900 rpm.Hull speed is a theoretical speed. You engine should be able to turn 3600 rpms in neutral and 3400-3600 in gear. If you CANNOT, then you may be over propped and that is why you are getting hull speed at a lower RPM. If you cannot run at 2900 rpm all day without belching black smoke you have some type of problem (mixing elbow, fouled prop, dirty bottom, over-propped etc.)

 

[David]

RPM

Bert, you may want to double check the engine model. Hunter installed the very heavy duty QM series at least as late as 1981. They turn a much lower RPM than the more light duty GM and HM series. By the way is your Tanzer 10.5 a pilothouse?

 

[Paul Akers]

3HM?

My Legend 37 has a 3HM35F and the Yanmar manual rates it at 3200rpm. I beleive the 3GM30F has 3600rpm rating.

 

[Guest]

If your max rating is 3200....

If you max rating is 3200, then you would have a normal operating range of between 2200 - 2600 RPM's.This would indicate that Bert is doing well moving the boat at or near hull spead at 2200.

 

[Bert]

3HM Series

David,It is definitely a 3HM, as written both on the motor and in the specs, and yes, the Tanzer 10.5 is a Pilot House.