Prop Spinning Undersail

[JamesG161]

I have read a few topics on transmissions gears but that does not seem an issue on my Volvo Penta reverse gear transmission in neutral.

I had the weekend sail in 20 knot winds and SOG of 7.2 knots. I went below for a bio-break and heard the whirl of my prop. This is the first time I have heard or experienced it.

It was gleefully spinning and I felt the sea water cooled (when engine running) transmission. No heat.

I ventured to use my thick rubber deck shoe heals to safely apply spin braking pressure and carefully brought the prop spin to a stop. Not a lot of pressure, but steady push.
When I released my "brake", the prop rapidly returned to a reverse spin.

My PSS dripless seal which is purged by the engine sea water pump, is now relying on sea water back flow alone, to keep it cool.

Would you let it spin or lock the spin down?

I have a keel/vertical prop alignment mark on the shaft.
Jim...

 

[Maine Sail]

My PSS dripless seal which is purged by the engine sea water pump, is now relying on sea water back flow alone, to keep it cool.

On a sailboat you just vent it for exactly this reason. On a power boat, where the water will be sucked out of the shaft log at speed, and does not move without the engine, they plumb it. On a sailboat you don't need nor want to plumb/feed the PSS just vent it. Plumbing it is actually not desired on a sailboat.

Would you let it spin or lock the spin down?

I have a keel/vertical prop alignment mark on the shaft.
Jim...

You will sail faster free spinning and Volvo, unless things recently changed, usually disallows for reverse and insists on free spinning with a fixed prop. If you had a Yanmar they also disallow locking it in reverse other than by using an aftermarket shaft brake.

Volvo Manual Quote: "If the boat has a fixed propeller, the control lever must be in the neutral position when sailing."

 

[JamesG161]

On a sailboat you don't need nor want to plumb/feed the PSS just vent it. Plumbing it is actually not desired on a sailboat.

You are right if you have the recommended vent height above the waterline per PSS. In addition there is a compression forward thrust to momentarily "spurt higher". I had no ability/space to do this. In talking directly to the PSS service technician, I had to purge mine, with their hose tee adapter. If my boat could have vented it, I would have done it.
http://forums.sailboatowners.com/index.php?threads/water-in-engine.175063/page-2#post-1253716
My post #27 has a picture of my install. I had only 9 of the minimum 24" required to vent per PSS.

Volvo Manual Quote: "If the boat has a fixed propeller, the control lever must be in the neutral position when sailing."

I always do that.

There is only one gear in the transmission and it is Reverse. Neutral takes it out of gear.
Since the spinning prop by forward sailing, it took some energy from the "wind power". I have never seen it spin until I had 90% of max speed and time to go below for a mild adult beverage.

I was thinking that perhaps if I had set it parallel with my keel at slow speed, it would not spin as the boat increased speed.

My worry was more that it is essentially acting like I was running my engine in reverse gear or compressing my PSS seal without cooling.
Thanks...
Jim...

PS: I don't like an open line in my boat. Some, with vented PSS, have said they put that line in a nearby lavatory then sump pumps it above the water line.