Lavezzi 40: Turning props?

[Zanshin]

I would think that without drag aft or spinning or any shaft movement after feathering/folding, the engine and gearbox wouldn't care what the gear setting is. The problems are with non-lubrication when the engine is off and the prop is free-wheeling or if locked in gear then the significant pull aft of the prop and shaft.

[DotDun]

Originally Posted by Zanshin

Carstenb - I would think that if you put the gear in reverse it would cause your blades to feather quickly. I've got a folding prop as well and turn off the engine, then put the boat into gear in order to force the blades to fold, then put it back in neutral so that I don't inadvertantly start the engine while in gear. Once the prop is in low-drag mode there should be no pressure and no movement and so the position of the gear lever should make no difference.

Don't worry, your prop will never 'start' the engine.

[Zanshin]

DotDun - no, it won't but once it was inadvertantly left in gear and I had to start the engine unexpectedly in a narrow channel to avoid a potential collision and the engine wouldn't start and it gook me a bit to realize why. On the old boat I kept it in full reverse when sailing and there the engine would start immediately when I turned the key and then roar in full reverse... neither scenarios were pleasing. But I see that my original post wasn't clear, I certainly never expected the engine to spontaneously get started by the prop turning...

[cal40john]

Originally Posted by carstenb

Would this "not in gear" also apply to boats with a shaft version? I ask be cause I recently switched to a Maxprop, and while it is in neutral, it occasionally still spins (yes I know - this is probably because the prop is mounted too tightly, causing the vanes to bind and not feather properly). I will be loosening it come spring when I do a haul - but does putting it in reverse adversely affect the engine?

I doubt it has anything to do with too tight, as only the hub is held by the prop shaft nut. If there are too many threads exposed beyond the nut it will bind with the cone though (3.B.2 manual).

Most likely though it is behaving as expected and following the use instructions in the manual will solve your problems.

From the manual found at:
http://www.pyiinc.com/images/pdf/max...structions.pdf

5) PROPELLER USE The Max-prop works automatically. By putting the engine
in gear the blades will engage in either forward or reverse. The best way to
feather the propeller is:
• Power at 2 to 3 knots in forward.
• Kill the engine while still engaged in forward.
• When the engine has stopped, if the shaft is still spinning engage the
transmission in reverse to stop the freewheeling.
You can check to see if the propeller is feathered or not by taking the engine
out of gear. If the propeller is not feathered the shaft will freewheel like with a
fixed blade propeller.
In that case start the engine again and repeat the three steps. If your
propeller has been greased properly it will feather in a fraction of a second as
soon as you stop the shaft from freewheeling. Once the prop is feathered,
you can either leave the transmission in gear or out of gear, it does not
matter. DO NOT kill the engine while in reverse. In this case the blades will
be in the reverse position and will not feather. You can actually use this
feature to drive a shaft alternator.


RTFM

[DotDun]

Originally Posted by Zanshin

I would think that without drag aft or spinning or any shaft movement after feathering/folding, the engine and gearbox wouldn't care what the gear setting is. The problems are with non-lubrication when the engine is off and the prop is free-wheeling or if locked in gear then the significant pull aft of the prop and shaft.

WRT the SD20, I believe the oil pump is on the prop side of the clutch, hence normal lubrication will still take place when freewheeling.

The 'pull' from stopping the prop by putting the transmission in gear is (comparatively) insignificant and won't cause any damage. It's not near as much as under power in reverse.