Spinning Prop While Sailing

[FionaJC]

On my TMP12000 gearbox page;

It is permissable to allow the propeller to auto-rotate when sailingWhilst it will not damage the gearbox, it will obviously add to the wear of rotating parts. It may also be noisy.
DO NOT STOP THE PROP ROTATING BY SWITCHING OFF THE ENGINE WITH THE GEARBOX IN GEAR.
Doing so may result in the gearbox locking in gear, and require the box to be dismantled to free the lock.
You should ALWAYS select neutral before stopping the engine.
(Gear selection with the engine stopped will do nothing, as the box needs oil pressure to select.)
If by chance you forget to do this, select neutral and restart the engine at once. (Make sure you are well moored first as the boat will move in the direction last selected.)

[oldcal46skipper]

I completed Borg Warner school about 40 years ago and have repaired many. They should not be turning while sailing, as most lubrication is derived from the pump on the input shaft. While there is some splash lube on the output shaft bearing, it is inadequate for long term life of the gear. I do not repair Kanzaki, Hurth or ZF's as it is about the same as buying a new one.

On my Cal 46, which I have had since 1982 and have many miles, plus 3,600 hours on the Perkins 4.236 and many miles sailing with the 3 blade Luke Feathering prop, 22X22 and a BW 72C which I rebuilt in 1987, I always feather the prop by locking the shaft. When sailing at lower speeds, I gain .5 knots boat speed when the prop is feathered and have no wear on my vee drive or BW.

BTW, I have about 8 or 10 BW gears in my shop, various reductions available. I have been asked why do you have so many transmissions? My answer is the Borg Warners are better than most engines. I also have 2 Paragons ready to go.

[topmast]

Back when I started and before internet for advice, I made a spacer plate at the coupling .3/8 steel ,1inch bigger diameter ,couple of half by half" slots cut in circumference.Bolted on back of BW a drop down dog finger controlled with a choke cable.When engaged cable handle was in the way at gear control lever thereby avoiding the embarrassment of busting everything

[pbmaise]

Our velvet drive spins in neutral and the amount of sound is a good indicator of speed.

For fuel economy we use a big fixed prop.

The transmission is cool enough to hand touch even after a long period at high speed.

Note: High speed is relative. If we still sailed above 15 knots we would switch back to the MaxProp which is folding.

[GILow]

Originally Posted by ur2slo

I would venture to propose that the coefficient of drag depends upon the specific gravity of the said solution under effect of Coriolis parasitic induced drag at tip vortices affected by volumetric intake of C2H6O, along with a fair amount of ice!

EXACTLY my thoughts.

[GILow]

Originally Posted by topmast

Back when I started and before internet for advice, I made a spacer plate at the coupling .3/8 steel ,1inch bigger diameter ,couple of half by half" slots cut in circumference.Bolted on back of BW a drop down dog finger controlled with a choke cable.When engaged cable handle was in the way at gear control lever thereby avoiding the embarrassment of busting everything

Very neat!

[pbmaise]

After lots of failures Yanmar finally published an MSA prohibiting the locking of their gear boxes in reverse if not using a "shaft brake"...

[BentP]

Originally Posted by Mango51

I have a Perkins 4236 with a hurth hbw 450-2R.
At the helm there's a plate that says keep in gear while under sail. except when running the prop alternator.

I have the same on my Mango. Note that it says NEVER put in Forward when under sail!!

[SV Bacchus]

Originally Posted by a64pilot

Heck with it, get a folding / feathering prop, you know you want one

Don't we all?

[a64pilot]

I have heard of a plate mounted with a hole it that lines up with a hole in the coupling, a golf tee was used to lock the driveshaft, if you forget and or need to start the engine now, the golf tee shears and causes no damage.

[topmast]

Just happen to have a slightly damage Max (near new) 3 blade 18" 11/4 shaft .PYI says they can fix and stand by the repair. If interested 300 to me I send it to Seattle and it's yours.when you pay the repair. (sheared the lug on the main center hub)

[GILow]

Originally Posted by a64pilot

I have heard of a plate mounted with a hole it that lines up with a hole in the coupling, a golf tee was used to lock the driveshaft, if you forget and or need to start the engine now, the golf tee shears and causes no damage.

Similar concept to my system. I have a loop of 4 mm line around a flange bolt on the coupling.

I've broken it about three times so far from forgetting it was there. Now I tie a bit of line through the engine key to remind me.

[GlennGee]

Some great info here. Something I hadn't put much thought into.
I have a Bukh DV20 and I am not sure about the correct gear selection while sailing.I assumed it would be best to free wheel to reduce drag not realising that it could damage the box.
I have the original owners manual and instalation manual and neither has a recommendation.
Any opinions based on experience with this motor would be appreciated.

[GILow]

Oh goodness. Don't open the more or less drag can of worms. That debate is nearly as loaded as anchors.


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[dan swift]

I think yanmar says that if you put the transmission in reverse it will damage the engine if you sail to fast. I had my clutch honed by a yanmar guy I might have
got that from him