Cruising RPM for 2GM20F

[wipe_out]

For anyone with this engine what is your cruising RPM?
We tend to run about 2000-2200, after that it starts to feel like the engine is being hammered. The issue is that it also feels very slow. Water line length is 8.6m (28ft) and we only get about 3kn at 2000 RPM. I’ve long had a suspicion that the prop was under pitched so planning to do a run at all RPM and record speed to see what it looks like and when/if we can get to hull speed.

 

[Spyro]

It’s quite a fast revving engine where diesels are concerned . That engine is rated with a max rpm of 3600. So running all day at 75% is 2700rpm. I see to run mine around 2900-3100 to achieve 5.5knts on a 32 footer AWB. It was comfortable and smooth at that speed. I’d say you are running it too slow.

 

[Channel Sailor]

Assuming correctly propped then 2900 to 3000 or even 3100 is good for normal speeds. You may notice that Vas on here has the same engine on a generator which has a designed operating rpm of 3000. If I cruised my 29ft er with 2gm20 at 2000 all the time it would get very sooty in the manifold. 2000 rpm is just trolling speed. Also 3Kts it’s is too slow for getting anywhere. BTW just thinking about it, 2000 on my light 29fter I think give a little more than 3kts.

suggest you clean the bottom, find some flat sea, no wind, Set WOT. It should be I would guess 6kts or even more at 3300 to 3400. Check the manual for the F because I vaguely recall continuous rating is 3400 and for periods of one hour is 3600 rpm.

Whack that throttle open, it is suposed to be a high ish reving diesel.