What RPM for Yanmar in continuous operation ?

[Delawaredave]

Newbie. Hunter 27. Yanmar 1GM.

What RPM do you run for "general cruising" ?

Looking at my manual, below, looks like 3,400 ? Sounds high - I've been running at 2,200.

Appreciate any insight. Thanks !

 

[BruceG]

Hi Dave,
I have a 1GM in my Hunter 27. I usually run between 2800 and 3000 rpm. 3000 is about max when transiting under power. The only time I can get it above 3000 is when I am dockside.

 

[kloudie1]

First thing to do is to check your tachometer .(Use a digital sort of like this http://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html .) The Yanmar supplied tachometers are notoriously geframitzed.. Then once you know what the tach means when it reads a number, use 2400-3000 (real RPM) or someplace in there to keep it happy.. Find a sweet spot and use it.. Too slow and you'll carbon up the elbow

 

[Sailgunner]

On the top of you engine is a plate. It will indicate what your continuous and maximum RPMS should be. If it says your continuous is 3400 then you can run 3400. The Yanmar rep said you should run at or near your continuous rating as much as possible. Now, your fuel economy will be less at the continuous rating so you might run at lower speeds at times if you are interested in economy. Frankly most people run their engines too slow. If in doubt call a Yanmar engine representative.

 

[Steve Dion]

http://yanmarhelp.com/operate.htm

If you are not getting the proper speed at the recommended RPM's you may need to have your prop checked. We have heard many complaints about lower speeds and it is usually an incorrect prop, assuming your engine is operating properly.

 

[RichH]

Industry standard 'rule of thumb' to result in longest service life of most diesel engines is to operate at 75% of max. rpm / or the '1 hour rating output'.

In this case 3600 rpm X .75 = ~2700 rpm .... your typical 'best' cruising rpm (assuming a 'properly pitched' prop).

 

[Sailgunner]

Industry standard 'rule of thumb' to result in longest service life of most diesel engines is to operate at 75% of max. rpm / or the '1 hour rating output'.

In this case 3600 rpm X .75 = ~2700 rpm .... your typical 'best' cruising rpm (assuming a 'properly pitched' prop).

I don't understand this kind of advice. Don't go with someone's "industry rule of thumb." Go with what the manufacturer recommends!

 

[RichH]

The manufacturer has NO input on the 'loading' thats placed on an IC engine ... and thats why you dont want to run an engine at its 'peak' on the HP vs. rpm curve that the engine manufacturer (can) supplies. This curve/plot will insure that the engine is operating at a relative minimum combustion chamber pressure and ensures or will indicate that the engine is not 'lugging' (too slow rpm vs. HP 'demand') - 'lugging' will result in extreme cylinder wall, connecting rod bearing, etc. wear.

 

[Alan Gomes]

Info from the GM operations manual

Attached is the relevant page from the Yanmar GM operations manual.