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Spiritman 02-18-2009 05:14 PM

Danger Will Robinson - Danger!
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This subject may have been tackled before, but I haven’t seen it in this forum.

Early February, central Chesapeake, 62 degrees – we’re goin’ sailing!

I disconnect the shore power cord (first at the dock) then coil it up as I move around to the connection port in the cockpit. I loosen the black ring – as I’ve done hundreds of times before – yet the cord seems to be glued in place. After giving it a good tug, it separates to reveal this: (see images below)

All of the AC wiring, and the breaker panel on the boat are less than five years old, and the power was still flowing – no breakers had been tripped.

I took the cord to the local WM and showed it to a seemingly knowledgeable fellow who was certain that moisture-induced arcing was the culprit. He said it was not an uncommon phenomenon. All it takes is a little moisture to work its way between pin and socket and POW. Sometimes it could burn your boat up. He said it doesn’t necessarily damage any of the boat’s internal wiring (but strongly suggested inspecting everything thoroughly – which I did). He also said that this could happen regardless of the amount of load on the line. In fact, this could occur without ANY load at all.

I’ve since replaced the socket and the power cord, just to be safe.

Can anyone add or refute any of this? Also, does anyone have any tips for preventing it?



Islander30Bahama 02-18-2009 06:25 PM

A product that I have used for years is Grote Ultra-Seal it is a non conductive grease that encapsulates the connection to prevent moisture from getting in between the conductive surfaces. I used this stuff in the Coast Guard all the time on receptacles out on the decks. Before a storm or heavy seas I would go to each outlet and put this stuff in the receptacle to prevent sea water from getting in and causing unwanted grounds. It saved me a lot of repair jobs and was well worth it. Hope this helps.


Spiritman 02-18-2009 07:01 PM

Thanks, Jeff.

Would this product work for cords that were being repeatedly connected and disconnected?


Islander30Bahama 02-18-2009 07:17 PM

I found that if you pack the receptacle side you will get a few plug and unplugs out of it before you need to squirt a little more in. It will go a long way. I use this stuff on pretty much any kind of electrical plug. I have used it on VHF antenna cables to canon plugs used on radar systems. West Marine sells one but I have found cheaper versions at auto parts stores that are just as effective cause you know when the word Marine gets put in front its good reason to double the price. What your looking for is a Dielectric grease to prevent corrosion and moisture caused arcing. Spending a lttle on this could prevent major arcing in the future and possibly your boat.


bubb2 02-18-2009 07:19 PM

The cord looks like it is a MARINCO. If it is and under 5 years old it is under warranty and I would think that West should replace it as it could be the cause of your problem.

Islander30Bahama 02-18-2009 07:30 PM


Also one thing that I forgot to mention was when I say receptacle side I mean the female side to put grease in. So you could grease at the shore power receptacle on the dock then the female plug on the cable.


Spiritman 02-18-2009 08:02 PM

Bubb -

I was unaware of the warranty - thanks.

Jeff -

Appreciate the info. I'll check it out.


farmboy 02-18-2009 08:24 PM


Any shop that installs trailer hitches/light hookups should have dielectric grease.

xort 02-18-2009 08:32 PM

those 30 amp twist locks are terrible
they often make poor contact which causes arcing which caused the problem you have. Make triple sure you have a solid contact EVERY time you plug in.

I doubt marinco will give you a new cord. operator error or a bad plug on the other end can easily be blamed. Please let us know if you succeed in getting a free replacement

this happens ALL the time, ask around the docks to see everybody's plugs, you'll see plenty of burned connectors

hellosailor 02-19-2009 02:25 AM

Salt spray can form a conductive film on anything. I'd second the vote for grease. Silicon dielectric grease, aka "high temperature brake grease", will also do the job and may be easier to obtain. $8 for 1/3 ounce from the Ancor brand at chandleries, or $5 for six(?) ounces at an auto parts store, pretty much the same stuff.

The other thing to do might be to try keeping the connections out of the weather, using a leather or vinyl cover over the sockets, and an occasional fresh water rinse--or something similar to make sure salt spray isn't building up on them.

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