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Old 01-24-2021, 03:45 PM   #12
BrisHamish
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City: Brisbane
Vessel Name: Beluga
Vessel Model: Grand Banks 46eu 2006 hull#289
Join Date: Apr 2016
Posts: 223
I am with Xsbank on this.

The manufacturer’s manual for your new engines will tell you what you should, and should not, do with respect to rpm and rated speed. Look closely at the recommended performance and fuel curves and the rating. These will be different for each manufacturer, and for each different capacity engine in a manufacturer’s range.

Cylinder glazing is a real thing (due to chronic underloading), and at the other end of the spectrum overloading (due to continual overpropping) is also a real thing. Both are best avoided. Your engine manual will tell you what is required.

I repowered in 2020 with a set of new QSC8.3 at 550hp, and the engine manual (and the performance and fuel curves and rating contained therein) tell me everything I need to follow about loading /rpm / fuel use. I admit it took me several reads and a little while to be able to properly understand them because they are not simple (and a nod to Tony Athens and his forum which explained how to understand this stuff), but once you know how to interpret them the answers are all there.

Hope this helps!

Hamish.
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