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Old 05-11-2014, 02:59 PM   #11
AusCan
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City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,902
With the handheld tach - You can either use it on the shaft for a direct prop rpm, or on the flywheel for engine rpm, and multiply by your gearbox ratio to calculate prop rpm.

Regarding raw water cooled engines - I've got an old Volvo MD17 which is the daddy of the MD2. I flush it with fresh water only when its going to be sitting for a week or more. If its only a day or two I don't bother. They are very heavy walled and designed to handle the salt water. Besides - Mine already has had salt water in it for 30 years. Its a bit late to keep it pristine.

The main issue is a slow blockage in the exhaust manifold water passages, which requires removal and cleaning with a bit of wire occasionally. When the engine starts running a bit hotter than usual, it's time. Not a big deal.
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