Prop Spinning Freely - Borg Warner - Shaft Lock

[Hampus]

Hey!

We have a hydraulic Borg Warner transmission. So, we can't lock the prop by putting it in reverse while sailing. When we're pushing 3 knots the prop is always spinning freely. I guess the transmission is designed for this and will be OK? My concern is for the prop shaft thru hull, the stuffing box. It seems that several thousand miles of sailing will cause excessive wear that can be avioded if the prop could be locked. Is this a non issue, or should I just tie a string around one of the bolts between the shaft and transmission and lock it like that?

/Hampus

[s/v Moondancer]

Yo can buy a $700 custom shaft lock or like me just put a large vice grip on it and remember to remove before starting the engine. We have a red cloth that covers the starter key to remind us the lock is on.

[SariTimur]

Don't let it spin too long. Without the engine running there is no cooling flowing through the heat exchanger and it gets hot, too hot. You oil discolours and bearings wear out. Been there done that. Pipe wrench works good also we used to use a disk break from a motorcycle and modified it to fit on the coupling. Now we use a Maxprop less worries more power in reverse etc.

Cheers

[Christian Van H]

Originally Posted by SariTimur

Been there done that.

Wait...you had damage from a Borg Warner transmission freewheeling? Wierd, the manual states that its fine...please elaborate.

SEE HERE: http://www.cruisersforum.com/forums/...ing-19895.html

[lancelot9898]

Originally Posted by SariTimur

Don't let it spin too long. Without the engine running there is no cooling flowing through the heat exchanger and it gets hot, too hot. You oil discolours and bearings wear out. Been there done that. Pipe wrench works good also we used to use a disk break from a motorcycle and modified it to fit on the coupling. Now we use a Maxprop less worries more power in reverse etc.

Cheers

I also have the maxprop with a borg warner tranny and for a number of years just sailed with the tranny in neutral. Not sure if there is more resistance if I set the tranny in forward or reverse when shutdown so as to put more resistance on the shaft to help the prop feather better. Comments??

[Hampus]

Locking it with a vice or shaft lock is not an option for safety reasons. We sail short handed and if one of us were to fall over board at night, having to run down to unlock the shaft would with 100% certanty mean that contact is lost with the person in the water.

Manual sais that freewheeling is OK and the manufacturer wouldn't sell a transmission that is self destructive while sailing.

My concern is still the stuffing box. Has anyone tried locking the shaft with a string around one of the bolts? The string will break if you forget it or need the engine in an emergency.

/Hampus

[roverhi]

The vice grip works fine, even in an emergency. If you forget or need to spin the prop without disconnecting it, just do it. The vice grips will unlock and drop off the prop shaft when they bang into whatever. Did it a couple of times, by accident, on my old boat.

[skipmac]

I second what Roverhi said. Exact same experience. Used vice grips to lock the shaft but got in a tight spot once and had to crank up and move immediately. The vice grips just popped off into the bilge. No damage to the shaft, the transmission or even the vice grips.

[barnakiel]

Transmission - do not guess, ask the people at Borg.

Yes, there will be more wear on the shaft / bearings - but how much engine-hours equivalent you guess? (vis a vis you engines motoring rpms).

And if you lock it, you will go slower ...

I think, if there is no damage to the transmission, let it roll.

b.

[Hampus]

Roverhi and Skipmac, thank you. That's good to know and I'll try the vice grips.

Originally Posted by barnakiel

ngines motoring rpms).

And if you lock it, you will go slower ...

b.

Actually, the prop creates more drag if it's spinning freely, so the boat will move faster if the prop is locked. Same principle as when a helicopter with engine failure autorotates to a safe landing.

/Hampus

[Christian Van H]

I'm trying to think...How did Captain Picard stop the Borg? Damn, I cant remember...

I have the Velvet Drive Shop, Installation and Owners manuals in PDF form. PM me with an email address if you need them...

[captden]

Originally Posted by Hampus

Roverhi and Skipmac, thank you. That's good to know and I'll try the vice grips.



Actually, the prop creates more drag if it's spinning freely, so the boat will move faster if the prop is locked. Same principle as when a helicopter with engine failure autorotates to a safe landing.

/Hampus

Are you sure about that, I thought an airplane would feather it's prop when the engine failed as it created less drag than being locked down. I would think it would be the same on a boat. It's the noise of the rotating shaft that makes me want to lock it down

[Beausoleil]

Originally Posted by lancelot9898

I also have the maxprop with a borg warner tranny and for a number of years just sailed with the tranny in neutral. Not sure if there is more resistance if I set the tranny in forward or reverse when shutdown so as to put more resistance on the shaft to help the prop feather better. Comments??

Check the Maxprop manual. The way to get it to properly feather (least resistance) is to shut down the engine while in forward. Slow the engine to idle for a few moments, then shut it down. I can verify that if I shift to neutral and then shut down the engine, the prop shaft will still spin. So shut it down while in gear to make it work as designed.

One feature of the Maxprop is that you can actually lock the blades in place by momentarily shifting to reverse, then shutting down the engine. This is useful if you've fitted a shaft alternator to help charge your batteries while sailing. You'll lose a knot or so of speed, but like all things in a boat, you compromise...

[Christian Van H]

Feathering means to turn the blades into the wind to lessen drag and, if possible, stop the prop from freewheeling completely. A spinning prop has (almost) the same drag as a solid disk the same diameter. Pilot ground school stuff...

[skipmac]

I read an article some years back that published their results on sailing with prop locked vs freewheeling. Their conclusion was the freewheeling prop generated higher drag. Freewheeling apparently builds a ball of water spinning with the prop that is pulled along with the prop creating more drag than the non spinning blades of the prop alone.

With an airplane propeller I believe feathering involves turning the edges of the prop towards the wind and the prop does not spin at all. Of course presenting the edge of the blade to the air stream will result in the lowest drag. Feathering boat props would do the same.

For me, wear or other issues aside, I like to stop the shaft from freewheeling because most of my boats have been aft cabin with the prop under my bunk and the spinning shaft is noisy.