Re: [Amel] Ideal cruising rpm

Eric Lindholm <etlindholm@...>

One of the best things you can install on your motor to detect any problems is a
boost guage and a pyrometer. If you know your boost at cruise and max RPM and
your exhaust temp at the same, it is a lot easier to trace any problem. If your
motor won't make RPM, then you will probably have low boost (turbo problem).
High temp, load on the engine, prop. A good diesel mechanic, and yourself once
you get used to the readings, can troubleshoot just about anything dealing with
the combustion cycle with these two tools. Any change from the norm will give
you an early warning that something needs to be checked.

Eric Maramu 105

From: Duncan <>
Sent: Fri, April 6, 2012 7:12:19 AM
Subject: RE: [Amel] Ideal cruising rpm

Hi Danny,

In explaining my problem on Dreamtime II I failed to mention that on the second
time I took the boat out for trials the rpm’s did ‘mysteriously’ jump up to 3000
in gear when I throttled up trying to get her to move out of the 1800 range. The
speed picked up to a little over 8k, but I recall I was into the wind and some
choppy seas. It has never responded that way again and I have been out sailing
and using the motor for a month.

Could it be that the prop changes will just not adjust and acts as a drag on the
engine. From comments it may be that engine failure is a result of attempting to
make the prop respond and the drag is stressing the drive. I’m no mechanic but
something is just not right between the transmission and the thrust coming off
the prop. The engine is fine with no load. I have looked at the engine and the
brake and it does not appear that the shaft is not spinning properly.

All this said, it seems that there is little need to ask the engine to run at
over 1800 +/- for the fuel consumption is good and the seed in average seas and
wind age is around 7 k/h. The problem I have right now is I need more power
maneuvering the boat and when you ask for maximum thrust you want it right then,
not after the boat has gained hull speed. I also see the need for RPM’s for the
cleaning of the exhaust. I suppose one could go to neutral and blow it out.

From: []
On Behalf Of Danny and Yvonne SIMMS
Sent: Friday, April 06, 2012 12:17 AM
Subject: Re: [Amel] Ideal cruising rpm

Hi Barry, we cruise at 2000 rpm generally. At 6 knots you cover the ground well.
We had the rpm problems that some seem to have with the TMD 22, 2800rpm max in
gear but cheerfully running up to over 4000rpm in neutral. Ours self corrected
suddenly when we were in Tahiti, now will achieve 3700rpm under power. Hasn't
changed my cruising rpm though, still believe 2000 a good speed. Higher revs
seems to increase the fuel consumption expotentially.
SM 299 Ocean Pearl
New Zealand

From: Barry < <> >
To: <>
Sent: Friday, 6 April 2012 11:30 AM
Subject: [Amel] Ideal cruising rpm

Recently, I serviced our turbo on our TMD22-A only to find it was badly carboned
up and the turbo boost relief valve had seized closed. We have replaced the
injectors and a new Garret turbocharger. Needless to say the engine is running
very smooth now however, I was wondering what rpm other owners are cruising at
under power alone. In the past we have been cruising at 6 knots at 1900rpm with
a clean bottom. Those of you who have a similar engine, what economical speed do
you find best?

Best regards
Barry & Robyn
Tradewinds III SM 171

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