Re: prop suddenly turning

Danny and Yvonne SIMMS

Hi Miles.

I speak from experience with the Hurth/ZF non hydraulic gear box. The insructions that came with my new Volvo D2 75 on a helm station decal is to have the gear either in neutral (spinning freely) or reverse, never forward.HOWEVER, the purpose when in gear is to stop the prop rotating at all. The slow spin you are seeing will be wearing your plates. Put it in the gear that stops the prop dead. I have a wierd experience. Sometimes that is forward gear  sometimes reverse. What I do is lift the engine compartment lid when I stop the motor and am sailing with the gear in neutral. Prop spinning merrily. I put it into gear. If there is a satisfying clunk and the prop stops dead. Thats the gear I leave it in. If it slows without the clunk  I put it in the other. I have no idea why, but it has worked like that for years.  I know the slow spin is damaging. There is no rhyme nor reason to this.



SM 299

Ocean Pearl

On 28 October 2019 at 04:05 Miles <milesbid@...> wrote:

Dear Amelians,
I am heading for Bermuda and then Marinique..  I just noticed that the propeller shaft was turning when I was sailing and the throttle handle was flat forward as Amel said to dol.  I have no shaft break and an AutoProp propeller.  My boat is SM 216.  I have owned it from new.  There is a placard attached to the boat in front of the shift lever.  The placard says, quite strongly, to always have the shift  in forward when sailing and I have always done this.  Just now, I noticed that the shaft was rotating slowly with the gear in forward and the boat going about 5 knots. It was slow and I could stop it with my foot.  Does this mean that the clutches in the transmission were slipping and wearing?   I don't understand how the shaft can turn when it is in gear and the engine is stopped.
I tried putting it in reverse and the shaft stopped.  Doing this means passing through neutral to start the motor.  In neutral, the prop spins fast in reverse and putting the transmission in forward causes a big jerk on the transmission clutches. 
I don't know what to do and I would be grateful for advice.
S/Y Ladybug, sm216  350 miles NW of Bermuda.

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