Long Distance Slow Speed

[elad9000]

The wife and I are looking to do some cruising and we have all the time in the world.

Anyone see any problems running for hours on end at say 1500 RPM?

[RobS]

A question better asked on www.boatdiesel.com

[chiefrcd]

What engine do you have? What boat?

I do know that Yanmar does not recommend long slow trolls without "blowing" out the carbon for about 10 mins or so. For ME on my 28' TE with a 6lp 300 ste the long slow trolls are at 750 rpms or so and last for 3 to 4 hours.......and blowing out the carbon is about 10 mins at 3600 rpms. (your carbon build up and blow out time might vary).

I think for me 1500 rpms must be about 10 or 12 knots... that causes me to push an awful lot of water. I seem to be very efficient up to 1000 or so rpms...then the boat seems to strain until I get up on a pretty good plane...which for me is in the 2800 to 3000 rpm range depending on the boat load and how clean the bottom is.

Some of the low speed diesels can run for years at low speeds and never have a problem. Yanmars are considered high speed diesels.

[AlanD]

I troll around 900 RPM for hours with drift socks, keeping me down to around 2.3 mph. The drift socks really help in letting me keep the engine up and oil pressire up. But she sometimes coughs a bit when I bring her back up to 3000 RPM for the run home, though lately she has been better. (Yanmar).

[Mariner]

As long as you run it up under load every once in a while, it's just fine.

[SkipperB]

I have just finished a 600mile++ cruise with an average speed of 8 knots with out any problems.I ran the motor(450HP Cummins) up every few hours Also averaged just a little under 3 MPG

[TD]

I would recommend calling your local marine Cat, Cummins or whatever engine you have. I did call Cat when I had 3208 turbo engines in my 39' SeaRay and ran at 1200 to 1500 day in and day out on a 5 week trip. No problems.

[Gary J]

The wife and I are looking to do some cruising and we have all the time in the world.

Anyone see any problems running for hours on end at say 1500 RPM?

We have alot of slow speed zones here in SW Florida for Manatees. We typically run through them at 1300 to 1500 rpm, which is in the 6 to 8 knot range with our 315 Yanmar. We find this to be a very efficient speed with the bow fully settled in the water. Also when in no hurry we'll cruise extensively at this speed. I always try to run it up to 3200 or more for a bit before heading to the dock to blow out the carbon, per Yanmar recommendation. Always has run great.