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Old 04-04-2009, 21:51   #16
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Discussions on freewheeling are bit like those on the correct anchor - everybody has opinions.

However, there is a difference. With freewheeling, some gearboxes need the shaft locked, and some need the shaft not to be locked.

YOU MUST READ THE GEARBOX MANUAL
OK, I'm confused

If the shaft is locked, and it is attached at one end to the propeller, which is now not turning as the shaft is locked, wouldn't that mean that the other end of the locked shaft would be attached to the gearbox that could not be turning as the shaft is locked preventing the propeller from turning ?

How then could anything be freewheeling?

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Old 05-04-2009, 04:09   #17
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Some gearboxes are not designed to take the stress of continually holding the shaft stopped, thus MUST free wheel.

Some gearboxes are not designed to freewheel as their oil supply is not pumping when the engine is not turning. These boxes must not freewheel. The only way to be certain is to read the manual.
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Old 08-04-2009, 15:00   #18
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I tried both in gear and out of gear on a 5 hour run on Monday. I couldn't tell the difference in performance over a 1 hour run. I kept the RPMs consistent and distance covered had less than a 2% difference.

Running Yanmar 3ym30s with SD20 saildrives. Running one engine at 2800 RPM, 3 bladed fixed props. Speed averaged 7.12 kts in gear and 7.05 out of gear (but unable to account for tidal or wind variance. It was gusting up to about 25 kts at times, raining at other times.)
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Old 08-04-2009, 18:24   #19
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raining at other times.)
That'll slow you down

Folding /feathering props or fixed?

I would assume folders, so it would make sense that there wouldn't be that much difference in or out of gear.

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Old 09-04-2009, 08:05   #20
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I, unfortunately, still have 3 bladed fixed props. I am SERIOUSLY thinking of getting the Kiwi feathering props. But, since it is x2, thought I'd save that for the next haul.... But that's a different thread!
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