Fitting a Prop

[a64pilot]

When fitting a prop on a boat that is out of the water, why would you not want to coat the shaft with anti-seize when you fit a prop? There is no movement between the prop and the shaft to cause wear and anti-seize would make removal of the prop at a later date much easier.
I can't see any reason not to use it?

[GordMay]

Make certain that you don’t use a product that is copper, aluminum, or graphite based, which can cause galvanic corrosion.

Ie: Anti Seize Compounds from Permatex and Bostik Never-Seez - Industrial Supply Group

[Ziggy]

The stock answer is that in a taper joint, you need to have tight fit and friction between the prop and the shaft for a secure mount, because the key could shear off if high torque is applied. Antiseize acts as a lubricant and allows the prop to slip relative to the shaft, shear the key, and possibly fall off. For this reason, prop manufacturers generally recommend against applying antiseize.

A possible counterargument is that the shaft key can serve as a mechanical fuse and protect the transmission from damage if the prop wraps a piece of rope or hits something. The prop nut, if securely pinned, should prevent the prop from falling off.

[a64pilot]

Good point. Truthfully I hadn't even thought of that, although I think the stuff I normally use is actually molybdenum grease really.
Is this suitable do you think? Any reason not to use anti-seize other than galvanic issues?
Never-Seez® Black Gray Mariners Choice Anti-Seize Lubricant, 16 oz Brush Top Can | Staples®'

Lord knows why Staples has it, I don't.

[a64pilot]

Ziggy,
I didn't see your post until after I made mine, I'm slow, very slow typing.

[Ziggy]

For the past several years, I lightly coated my shaft with tefgel. No risk of galvanic corrosion, the prop easily comes off for the winter, and the the shear key is still intact. Just be aware that this goes against the conventional wisdom and YMMV.

[a64pilot]

this is what I normally use
http://www.amazon.com/Permatex-80078...ref=pd_cp_hi_1

Read the description, a little mis-leading maybe?

Permatex Anti-Seize Lubricant is a highly refined blend of aluminum, copper and graphite lubricants, for use during assembly to prevent galling, corrosion and seizing, and to assure easier disassembly. Featuring salt, corrosion and moisture resistance, this lubricant is ideal for marine use.

[model 10]

Originally Posted by Ziggy

The stock answer is that in a taper joint, you need to have tight fit and friction between the prop and the shaft for a secure mount, because the key could shear off if high torque is applied. Antiseize acts as a lubricant and allows the prop to slip relative to the shaft, shear the key, and possibly fall off. For this reason, prop manufacturers generally recommend against applying antiseize.

A possible counterargument is that the shaft key can serve as a mechanical fuse and protect the transmission from damage if the prop wraps a piece of rope or hits something. The prop nut, if securely pinned, should prevent the prop from falling off.

Boy there is BS in there. First off white lead is used on tapered shafts all the time (aircraft mechanics should know that.) Second, the key does squat, the taper keeps the prop from turning. Same goes for the nut.

[a64pilot]

Yeah,
I'd have to say the key does a lot, maybe not normally, but I think it prevents rotation when a shock load is applied, else why bother with a key?

I do think anti-seize will not be enough of a lubricant to shear the key and allow the prop to spin on the shaft though

[model 10]

Originally Posted by a64pilot

Yeah,
I'd have to say the key does a lot, maybe not normally, but I think it prevents rotation when a shock load is applied, else why bother with a key?

I do think anti-seize will not be enough of a lubricant to shear the key and allow the prop to spin on the shaft though

Any machinist who knows about tapers will tell you, with the interference fit on a taper you don't need a nut or a key, unless the prop starts to come loose while you're backing up.

As for an anti-seize compound, it's more important if you have 2 steel parts together, like a stainless prop and a stainless shaft.

[fstbttms]

Nothing should ever be applied to the interior bore of the propeller hub, or the shaft taper when installing a prop. The tolerances are so close that putting anything between the surfaces can cause the prop to fail to seat properly.

[model 10]

Originally Posted by fstbttms

Nothing should ever be applied to the interior bore of the propeller hub, or the shaft taper when installing a prop. The tolerances are so close that putting anything between the surfaces can cause the prop to fail to seat properly.

You do have internet don't you? Just to get you up to speed, finally, search "white lead on prop shafts".

[Terra Nova]

Originally Posted by fstbttms

Nothing should ever be applied to the interior bore of the propeller hub, or the shaft taper when installing a prop. The tolerances are so close that putting anything between the surfaces can cause the prop to fail to seat properly.

This is correct.

[a64pilot]

Originally Posted by Guy

Any machinist who knows about tapers will tell you, with the interference fit on a taper you don't need a nut or a key, unless the prop starts to come loose while you're backing up.

I'm not arguing, but if there is no need, why is it there? I've seen keys that were a little too tall and or not seated properly cause problems as the prevent the bore from properly seating on the taper, so it would seem that if it's not needed, the proper thing would be to not install it.

[fstbttms]

Originally Posted by Guy

You do have internet don't you? Just to get you up to speed, finally, search "white lead on prop shafts".

Yeah, 'cause everything you read on the internet is true.

You do it your way, I'll do it the way I was instructed to by the manager of the prop shop at the largest ship repair facility in Northern California.