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Old 10-01-2019, 11:14 AM   #19
Waterant
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City: Woodbridge
Vessel Name: DORA
Vessel Model: 2002 Mainship 430
Join Date: Oct 2018
Posts: 268
Thanks for the tip. The boat is already on hard and prop was as clean as on the day we dropped her in the water in May. This is the first summer I have this boat and not sure if this is a new issue. When I started this thread, the tachometer showed as little as 1500 RPM when we started getting visible smoke which got me alarmed. in reality, this was 1800-1900RPM (tach died completely by the end of the trip). I installed and calibrated with a laser handheld tachometer a Nmea 2000 integration which takes RPMs from the engine and another one from the alternator and was getting precise readings for the rest of the trip and kept RPM around 1700 with no smoke. The previous owner cruised around the same RPM so smoke probably did not bother them.

> In my case I went after the raw water system and found old impellar bits, mud,
> and old pieces of zinc in the heat exchangers.

You read my mind. this is on top of my to-do list. I did not think of it as a cause for the smoke because this does not affect fuel/air ratio but a good thing to do anyway and if that fixed your smoke issue, even better.

as I understand, I should not see any smoke on a warmed-up engine even at higher RPM as long as it's not getting into the overloaded territory and this engine is rated at 2800RPM continuous duty so the smoke starts around 70% of rated max RPMs.*It may be just a case with over-propping which I will not worry about but I want to be proactive and check/fix the possible causes outlined in the (much appreciated) replies I'm getting. I have a few boring months before the next season and removing injectors and disassembling the exhaust is within my limited abilities anyway
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