Cruising at higher RPM's

[jpwrist]

I am planning to take my 2001 28 TE Plan B with a 300 hp Yanmar 6LP STE from Galveston to the FL east coast and possibly the Bahamas. It is a long trip and I wish to make the trip to Apalachicola, FL quickly (done that, been there) and thus would like to run at relatively high RPM's. According to the tachometer WOT is between 3900 and 4000 RPM's. I am not worried significantly about diesel usage and am curious if running at 3400-3600 RPM's for an extended time would be bad for the engine. Note I usually run at 3100-3200 RPM's and 13-15 knots. At the higher RPM's I would average 16 to 18 knots and thus, get through Texas and Louisiana a little faster.

Are there any concerns with running the engine at such high RPM's for an extended period of time?

Jos

[Cape Codder]

Yanmar says you can run wide open for an hour with no problem.
Running at 85-88% will use more fuel, but should not bother anything.
Check all fluids before, and at every stop.
Watch your engine temp. and oil pressure. If they remain normal, you should be OK. (Won't be much carbon build up, that's for sure)

[Carl]

My cruise RPM has always been 3400 to 3450. Mine is a 2006 Flush deck with the 315 Yanmar. At these RPMs depending on bottom condition I cruise at 17 to 19 knots. This seems to be the sweet spot for my setup. Anything below 3300 it seems to work much harder at only 14 to 16 knots. I am getting the tach checked this spring to make sure it is in the ball park. I cruise at these RPMs for hours on end sometimes in all sea conditions with no issues as far as temp. My WOT RPM is 3950 full of fuel and water with 2,3,or 4 people. The only time it drops below that is with a slimey bottom, then its time to go swimming, or pull it and pressure wash.
Hope this helps.

[jpwrist]

Bob and Carl,

Thanks for the helpful comments.

I will change my habits and start cruising at approx. 3400 RPM.

Jos

[fuenstock]

I also have a 2006 28te flush deck with the 315 yanmar. I feel 3400 rpm is right where the engine likes to fast cruise.

[Capt Paul]

I have a 1999 28TE wit the 300HP Yanmar. When I first got the boat I would cruise around at about 32-3400 RPM, 15 -17 Knots. I talked to my engine mechanic about it one day, and he said just look at this way , with boat engines on non planning hull it like you are doing 60miles an hour in your car in low gear. when at higher RPM. It is just added punishment via heat and stress factors on the engine.

I took this to heart as I really want this engine and boat to last a long time and decided to pull back the throttle and cruise at about 2800 RPM , 13Kts. Works for me but the longest trip I have ever made is about 100 NM over a two day period.

Paul

[Carl]

A little more info and explanation.


http://www.youtube.com/watch?v=kvvlkswI ... re=related