Galvanic Conducting Grease?

Don S/V ILLusion · Apr 9, 2012

There is no such thing at least in terms of the name he portrayed it as. You can buy dielectric grease anywhere and it serves to promote good conductivity between dissimilar metals. whether or not it is necessary in this application is debatable - it can't hurt but my opinion is that it serves only to lighten your wallet. Assuming you are in salt water, the conventional wisdom is that it is a pretty good conductor all by itself.

kloudie1 · Apr 9, 2012

Duck, I dunno.. sounds like the same spec as for Skyhook Grease... Or Scuttlebutt Lubricant..
I'd venture to say that the normal metal-to-metal contact between the prop and the shaft would be plenty to conduct galvanic currents....if you really want them conducted.. The owners manual should have words about any special grease required if indeed it is.. The saildrive/prop nut anodes should be the only things necessary..?

gpd955 · Apr 9, 2012

It is a grease that prevents galvanic corrosion and is used in electrical and mechanical applications. Your shaft zinc usually serves that purpose.

kenn · Apr 9, 2012

Since the prop goes onto and is tightened against a tapered shaft, I have no doubt that there's already plenty of contact surface, for purposes of galvanic protection.

From what I can find out, greasing the shaft before putting the prop on serves two purposes:
- prevent the prop from seizing to the shaft
- filling the tiny gaps between the prop and shaft, to prevent corrosion in those places

Just a guess, but regular marine grease would probably be better than nothing for this purpose, too.

Ross · Apr 9, 2012

Dielectric grease is an insulator! http://en.wikipedia.org/wiki/Silicone_grease

Don S/V ILLusion · Apr 9, 2012

Ross said:
Dielectric grease is an insulator! http://en.wikipedia.org/wiki/Silicone_grease

This is a common misunderstanding. Like you said, it is not conductive, and therefore does not enhance the conductivity of a connection. What it does do, however, is help keep the connectors in good shape, that is, free of corrosion, debris, etc. Clean connectors obviously work better, so by keeping the connectors clean, dielectric grease does play a part in enhancing conductivity, albeit indirectly.
Again, as you said, the grease itself is an insulator, but keeps the parts that are conductive in good shape, so in the end the overall conductivity is enhanced.

Us ham radio operators discovered this decades ago to prevent corrosion and promote conductivity in our metal antenna structures.

All of which is moot given it is a non-issue on prop/shaft mating.

Ross · Apr 9, 2012

Don, When I was in the Air Force we had UHF antennas that had a glass insulator between the elements that had to be kept coated with silicone grease to defeat the salt spray from the South China Sea. We were out on a point. We had to check all of the antennas with a megger. When they didn't pass we climbed the poles and cleaned and greased them all.

heritage · Apr 9, 2012

There are greases that are specifically designed to conduct electricty such as this one: http://www.sanchem.com/aSpecialE.html . Note the test that Practical Sailor did with the grease, towards the end of the article.

I can see an advantage of using a dielectric grease on connectors that contain a pos. and neg. probe that are close together. The dielectric grease should decrease the chance of water or corrosion shorting out the contacts. But I wouldn't put dielectric grease between a battery post and the cable clamp.

Ross · Apr 9, 2012

I buy an equivilant at the electrical supply shop. and five ounce tube will last a residential electrician for several years

Fred Villiard · Apr 9, 2012

The conductive grease that electricians use on aluminum entrance wiring connections, has nickel particals to penatrate the aluminum oxide and the grease keeps it from reforming.

A company Cool-Amp Conducto-Lube Co. phone 503.674.6426, has a silver bearing compound that is used alot in the power industry for lubicating high power sliding contacts.

Fred

RichH · Apr 9, 2012

Fred Villiard said:
The conductive grease that electricians use on aluminum entrance wiring connections, has nickel particals to penatrate the aluminum oxide and the grease keeps it from reforming.

A company Cool-Amp Conducto-Lube Co. phone 503.674.6426, has a silver bearing compound that is used alot in the power industry for lubicating high power sliding contacts.

Fred

You can also get silver bearing compounds to enhance conductivity at HAM radio, etc. shops, but would be totally inappropriate for a prop/shaft application.

As far as a prop/strut interface, there is absolutely NO need for such as the ionic nature of the water in which the prop/shaft is immersed will make the 'electrical connection' if there is total 'insulation' between the prop and the shaft --- thats just simple electro-chemistry. If you were somehow using the prop as a radio, etc. antenna 'perfect' conductivity 'could' be a consideration, most certainly not in this case.
Since the water in which one sails doesnt have the resistance of 18 meg-ohms of 'pure' water, that advice that was offered is simply 'nonsense'.

Maine Sail · Apr 9, 2012

Ducati said:
My know-it-all boat neighbor drops by to give me advice always after I have completed the job.

I put the prop back on the sail drive unit and he said, of course you used some "galvanic conducting grease" on the sail drive casing the between the prop and the unit.

What is "galvanic conducting grease"?

Thanks

Got a left handed hammer..? Actually the last thing you want to add to your underwater hardware is an electrically conductive grease. They use zinc, aluminum or copper to aid in conductivity. Adding these extra metals will only exacerbate corrosion issues by adding one more dissimilar metal to the galvanic soup.. Regular old waterproof grease is often used on splined shafts to aid in removal but never on a tapered prop fit..

Ross · Apr 9, 2012

I have a metric adjustable wrench.

MrBee · Apr 11, 2012

Didn't know they made that type Ross....I'll have to look for one. My Yanmar needs metric tools and one Metric adjustable would be better than carrying many individual wrenches !!

Brian
Hey Ross, they fix the bulkhead at Owens yet ?

woodster · Apr 11, 2012

MrBee said:
Didn't know they made that type Ross....I'll have to look for one. My Yanmar needs metric tools and one Metric adjustable would be better than carrying many individual wrenches !!

Brian
Hey Ross, they fix the bulkhead at Owens yet ?

i hate to be the one to inform you but you need to look down to you right leg ....and you will find that Ross is pulling very hard on it

regards

woody

Ross · Apr 11, 2012

They were able to straighten the seawall in house. The Linkous family is in the construction business so they own the heavy equipment they needed.
I store my metric adjustable wrench in the same bag as my metric pipe wrenches.

Maine Sail · Apr 11, 2012

Ross said:
They were able to straighten the seawall in house. The Linkous family is in the construction business so they own the heavy equipment they needed.
I store my metric adjustable wrench in the same bag as my metric pipe wrenches.

Ross.

Craftsman has a new set of stainless Phillips & Slot head metric screw drivers, very sweet. They can also be purchased with the new metric level with "European" bubble. This makes working on European built boats considerably easier. Finding level on a metric boat is a pain without a metric level.......

Ross · Apr 11, 2012

Craftsman has always been cutting edge and fine quality.
I have recently seen tape measures that are marked in inches on one edge and metric on the other edge.