Yanmar engine RPM

[DownEast2]

I will be sea trialing a 28TE with a Yanmar 6LP STE engine. The engine has about 760 hours on it, about 3/4 full of fuel and not much of anything else. Can anyone help me, I would like to know the the cruising RPM should be and approximate speed and what WOT should be.
I appreciate any help you can give me.
Denis

[Jkraft]

The yanmar 6lp needs to reach 3800 minimum when loaded. It SHOULD reach somewhere over that, preferably around 3900.

Cruise RPM on them in our boats is 3200-3600. My boats happy spot is 3450 at 17-18 knots

[Norseman]

The yanmar 6lp needs to reach 3800 minimum when loaded. It SHOULD reach somewhere over that, preferably around 3900.

Cruise RPM on them in our boats is 3200-3600. My boats happy spot is 3450 at 17-18 knots

Sounds a bit low: My book says the WOT RPM in gear, underway should be 3950-4050 RPM.
The HP rating is 3800, max cruise (as in max Continuous RPM is 3600.)

I see 17 knots at 3600 RPM with 1/2 load and 1/2 fuel.

[Jkraft]

Sorry I was 50 rpm low….

[DownEast2]

Wow, those RPM ranges are far higher than I would have expected.
We had to abort our sea trial yesterday before I could even get on plane, the engine had a major water leak that was dumping water all over the engine and into the intake. But I was under the impression from the man driving the boat that cruise RPM was about 2800.

[Norseman]

Wow, those RPM ranges are far higher than I would have expected.
We had to abort our sea trial yesterday before I could even get on plane, the engine had a major water leak that was dumping water all over the engine and into the intake. But I was under the impression from the man driving the boat that cruise RPM was about 2800.

The major water leak could be the Raw water pump.
It is partly hidden under the engine and hard to see and to service, therefore
it can spray salt water around causing damage.

As for the wide RPM range: Yes, this is a high speed diesel, made by Toyota for the Land Cruiser SUV, then Yanmar got it and “Maranised” it.
It is a precision machine and needs TLC and it does not tolerate abuse like an old slow revving diesel such as a Perkins.

If your boat does not have the FloScan electronic tach, then RPM could be off a bit. Hopefully the surveyor will bring a stroboscope light to get the actual RPM. Anything less at full throttle than 3950 RPM the engine is Over Propped, or the prop is dirty with growth.
Long term over propping with these engines can cause damage as per the experts at Boatdieael.com. (Join that website, lots of info on the Yanmar 6LPs and every other marine diesel.)

Good luck.

[DownEast2]

Thank you everyone, for the information on the RPM, the leak was a water hose going to the after cooler I think. Its been repaired and Ill be going down for another sea trial. My fingers are crossed that it runs perfectly, I can't wait to own another Albin.