slow steaming

Hi guys, Im a N.A. (after my studies in Newcastle ME also )
Anyway, I have a question regarding the slow steaming.

First of all, I managed to understand that slow steaming is something like the situation below.
Lets says that I have a car engine... and I shift up at 2k rpm.. when I'll hit the last gear I stay and 2k rpm and keep going and going and going ..
At this given point I have a certain amount of PS(kw), torque, temperature, oil pressure etc!

More than that I noticed that companies perform "before" and "after slow steaming" reports. I know that an engine is able to operate for a short period at MCR or a bit more than MCR point.
So whats the problem if I operate my engine at 20% of load capacity?

All that in case I got natural aspiration engine. Maybe I got a problem in Turbo Engines.. for instance If I got a turbo which gives power at high rpm then my turbo will always be at "spooling phase". Just a thought!


John

 

If you compare a car with a boat engine, it will not help too much. The only similar comparison is a fully loaded vehicle going up a steep hill.

 

hmm really ? thanks

 

Cars accelerate which is when they have a lot of load. Then they keep the speed which needs a fraction of the power. Boats have a high load at all times. Planing boats have the possibility of using less power once they are up on plane. You can see this on the resistance curve of a hull.

 

You are really asking about what happens to an underloaded diesel.

Depends , mostly on the what OEM designed the engine for.

If it was for a taxi or light truck (Perkins Ford Lehman and dozens of others) slow running usually has little problem.

Even larger engines John Deere and other earth moving marinizations seem to do OK with light loads .

The problem comes with genuine heavy duty engines rated and used 24/7/365 in commercial fish boats or as pump or generator service.

These may suffer from under loading , cylinders burnishing , large blow by , high oil consumption and shortened service life.

For yacht service , who cares? , a 12,000 hour engine that gets 100-200 hours a year will "never" wear out in a pleasure boat service as 3000 hours takes decades.

FF