Prop shaft not turning under sail

[Tim22]

I have a 1997 Hunter 310 with a yanmar 2gm20f and leave the transmission in neutral when under sail. I noticed the other day that despite the transmission being in neutral the prop shaft was not turning even though we were sailing at 5.5 knots. Is this normal, or should the shaft be free wheeling? This is a relatively new to me boat so I am not sure if it has always been this way.

Thanks
Tim

 

[kappykaplan]

Do you have a feathering or folding prop?

 

[jssailem]

Fun question but need more information.

1. How many prop blades?
2. What type of keel/rudder structure do you have?
3. Folding prop?
4. What type of stuffing box? That's the connection between your hull and your shaft that stops the water from getting inside. Look at shaft coming from your transmission. Follow it down to the connection that looks like a rubber hose with the shaft going through it. That is the stuffing box. Check out Main Sails website for a great view of this important boat part.

• Traditional Stuffing box http://www.pbase.com/mainecruising/stuffing_box

A folding prop will collapse the blades when sailing. You should get no shaft rotation.


A two blade prop can align with a keel and ride it's slipstream. No rotation of the shaft.


A stuffing box that is not properly working, a bent shaft, or broken bearings in the cutlass all can affect the rotation of the shaft when not being rotated by the engine.

• Cutlass Bearing http://www.pbase.com/mainecruising/replacing_a_cutlass

So more information is needed.

 

[Calif. Ted]

Try turning the prop shaft by hand at the flange, if you can't turn it with one hand either a conventional packing too tight or one of the components John mentioned.

 

[Tim22]

This is a two blade prop. Keel is led - 4' draft. Stuffing box is the original brass identical to Maine's photo. It is scheduled to be re stuffed when the boat is out this winter.

I don't believe there is a problem with a bent shaft or cutlass bearing as the boat was surveyed a year ago prior to purchase in Michigan and after delivery in Ottawa and both reported these items in good condition. I will, however have them re checked when it is hauled. In the meantime I will try turning it by hand.

Thanks
Tim

 

[joker460]

When you're tied up and the motor is not running. Shift into neutral.
Can you turn the prop shaft freely. If yes then there's no problem and I would leave it.
If you can't turn the prop shaft then you may have a transmission issue.

 

[Scott T-Bird]

I've always wondered about that myself. I have a 2-blade and only hear it turn on occasions when I'm really moving fast downwind. It always seems to be vertically aligned when I dive under the boat after sailing. Self-aligning with the slip stream from the keel makes sense to me. If you had a misalignment or bent shaft, you would know it immediately. The vibration when motoring would be unbearable.

 

[Tim22]

Thanks for all the suggestions. I tried to rotate the shaft by hand today but no way it would turn. I will open up the stuffing box and re stuff when the boat is hauled next month. Also will have the transmission checked out.

Thanks
Tim

 

[Davidasailor26]

Thanks for all the suggestions. I tried to rotate the shaft by hand today but no way it would turn. I will open up the stuffing box and re stuff when the boat is hauled next month. Also will have the transmission checked out. Thanks Tim

Does the stuffing box drip when you're motoring? After motoring for a period of time, does the stuffing box become hot to the touch? If there are no drips and excessive heat, the stuffing box may simply be over tightened. If that's the case, avoid motoring too much until it's adjusted, or you risk scoring the shaft.

 

[jssailem]

Tim
I had my stuffing box serviced by a friend. We did it in the water. Stuffed a rag on the shaft to limit the water inflow and worked as quickly as possible. Deep bilge and good pump at the ready. Went smoothly, even though my 70 year old buddy said in all his days he has never worked on a more confounded, difficult, misguided engineered stuffing box. I asked him if we had hauled the boat would it have been any better? He said no. A little dryer, but not any easier. I suspect it will end up being 2 cases of beer, not one, and may be a dinner. I had fun being the gofer, learning, and listening to some salty language.

We could not get wrenches on the nuts to turn them. Had to resort to a steel bar and pounding it against the edge of the nuts to loosen them. Old school, slow, but worked.

Do expect some drip from the stuffing box while the shaft is turning No drip means heat. Heat means potential damage to shaft. Damaged shaft = $$$$$.

Best luck.

 

[Calif. Ted]

I had my stuffing box serviced by a friend.

Wish I had friends like that.
Tim, At some point you'll need to disconnect the coupling flange, then you can tell if it's the trans or the prop shaft components. You'll also be able to check your alignment. I'd guess you guys need to check the alignment at spring launch after being on the hard over the winter ?

 

[kloudie1]

Curious, Tim if you've disconnected the shift cable at the transmission and verified that it is "clicked" into neutral.
With the cable off, you should feel/hear a definite "click" into a detent when it is positively in neutral. Be sure to stop the engine in neutral before checking this.

 

[Maine Sail]

Thanks for all the suggestions. I tried to rotate the shaft by hand today but no way it would turn. I will open up the stuffing box and re stuff when the boat is hauled next month. Also will have the transmission checked out.

Thanks
Tim

This is most likely an alignment issue not a stuffing box issue.... For packing gland to be so tight, that you can't turn it by hand, you would probably be smelling the melting rubber packing gland hose when under power....