Applying Dielectric Grease

How can you create solid, protected electrical connection?


I’m confused about how to apply dielectric silicone compound or LPS-3 (spray) to electrical connections. These are dielectric substances (i.e., insulators), which would suggest that if you apply either one to the electrical terminals and then assemble the connection, you would increase the resistance, defeating your intentions. So should you just spray or spread it over a terminal block and consider it protected? Or does the compound get squeezed out sufficiently so that a good electrical connection is made?

Clifford Kurz
Voyager, Tashiba 40 #173
Jamestown, R.I.

For most electrical connections-anything bolted, crimped quick-connects, lightbulb sockets, and common 100-volt plugs-a dielectric grease or spray is the right answer. To apply, coat the contact surfaces and then assemble the connection as usual. The clamping pressure, whether a bolt or simply the pressure between the contact surfaces in most plugs, pushes the grease out of the way, providing a good contact. You should also coat or spray the outside (not on the lightbulb itself; that can cause failure on halogen bulbs). The remaining dielectric serves to seal the contact area from water, oxygen, and galvanic corrosion.

There are two exceptions to this practice. Grease is not dielectric at radio frequency, so it should not be used on radio antenna connections. When making antenna connections, simply get them as clean as possible and seal well. The other exception is when making connections in electronics where any lubricant will draw dirt and contact pressure is very low and may not penetrate the film. In these cases, clean the connection with contact cleaner or acetone, and try to keep them dry.

Finally, there are conductive greases, used in certain applications to reduce arc damage or bleed static. These are not required on boats. (In the December 2010 issue, we reviewed one such product, No-Ox-Id, which must be used only in the contact area.) Do not use these conductive greases around multi-pin connectors, as they can cause shorts. Applying a dielectric grease is better in nearly all cases, and silicone grease is the best.

For more on grease, see the July 2010 article The Wire Report and the December 2010 article Marine Wire Test.

Co-owning a boat

I plan to buy a sailboat with a few other aficionados. Can you refer me to a basic, boat-related joint ownership or co-ownership agreement/contract?

Richard Fritze

Via email

We contacted a few related industry groups to help answer your question, and the consensus seems to be that your best bet is to contact a maritime lawyer. While you can find sample contract templates through an online search (some for a fee), a customized contract will include more detailed operating parameters and will cover needs specific to your situation/boat. According to attorney Mark Buhler, chairman of the U.S. Maritime Law Associations (MLA) Recreational Boating Committee, these custom co-ownership contracts are typically crafted for co-owners who already know each other. If youre looking to get into a fractional ownership arrangement (like a boat timeshare set up by a promoter/manager), youll find many options online, as well as some sample fractional-ownership agreements. If you go this route, Buhler advised, be sure you have a clear understanding of how and when the promoters are making their money on the deal (and how much).

Vincent Petrella, executive director of the yacht brokers Association of Yacht Sales Professionals, YBAA (, explained that multi-owner/partnership situations can be very tricky and that in addition to spelling out who is responsible for which duties and costs, the agreement should include a clear definition of what happens if one owner decides to leave the partnership. Petrella added, It has been my experience that these types of purchases are done by establishing a business entity such as a corporation or LLC to shield the individuals involved against liability. My recommendation would be to contact a maritime attorney who has experience in setting up this kind of a partnership purchase.

Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida.


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