Yanmar 3YM20 max cruise RPM

[Letterkenny]

What is the max cruise RPM people use for the Yanmar 3YM20? 2800 seems to be decent tradeoff for speed and efficiency but seeking what I can run at if I need to do a 12 hour fast cruise home.

[Tin Tin]

The usual range is 70 -80% of WOT.


We have twin 3YM30s with Gori overdrive folding props, we run at 2800 - 3000 on one motor or 2500 each on two - we nearly always run on one for any distance longer than an hour.



See attached article for interest.

https://www.tradeaboat.com.au/news-r...-engine-review

[Wotname]

Max continuous rpm for the 3YM20 is 3489.
Max intermittent rpm is 3600.

[Letterkenny]

Originally Posted by Tin Tin

The usual range is 70 -80% of WOT.


We have twin 3YM30s with Gori overdrive folding props, we run at 2800 - 3000 on one motor or 2500 each on two - we nearly always run on one for any distance longer than an hour.



See attached article for interest.

https://www.tradeaboat.com.au/news-r...-engine-review

Well I think it’s 80% load but I haven’t a clue what that is with the basic engine controls. Great article though.

[Letterkenny]

Originally Posted by Wotname

Max continuous rpm for the 3YM20 is 3489.
Max intermittent rpm is 3600.

Did you get that from the same article or somewhere else? Would there be concern running it for long at that RPM? Granted, I think the max I would do is 3200 RPM but cruising at 3200 vs 2800 is about a knot pickup for me and on a 75 mile run, that can really cut down the transit.

[ScottRhodes13]

Continuous and Max RPM are inferred from the operators manual. That is, the rated Continuous power is achieved at an RPM of 3489.

Don't be afraid to run at this rpm, just watch for signs of overloading or overheating. (Black smoke or heavy steam out the exhaust or the temperature alarm going off.)

[Tin Tin]

If you are going to run at 3200 and have not done it recently, just make sure your impeller is pretty new and heat exchanger not blocked by broken blades, calcium etc. and elbow is clear. These things might be a little worn or constricted but not enough to worry the system at 2500rpm. If I were you I would take it for a run first at 3200 rpm for 1/2 an hour check with a heat gun at various points on the engine - if all with tolerances per manual it should be fine to do longer runs - assumes gearbox and other peripherals like V belts, alternator, coolant pump, thermostat are also in good nick.

[Letterkenny]

Originally Posted by Tin Tin

If you are going to run at 3200 and have not done it recently, just make sure your impeller is pretty new and heat exchanger not blocked by broken blades, calcium etc. and elbow is clear. These things might be a little worn or constricted but not enough to worry the system at 2500rpm. If I were you I would take it for a run first at 3200 rpm for 1/2 an hour check with a heat gun at various points on the engine - if all with tolerances per manual it should be fine to do longer runs - assumes gearbox and other peripherals like V belts, alternator, coolant pump, thermostat are also in good nick.

She was serviced about 40 hours ago/ 6 months and I do run her at 3000 for an hour or two here and there and run her at WOT for 5-10 minutes each outing. Just never ran her at 3200 or 3400 for a long period of time.