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Seacock ground

6K views 4 replies 4 participants last post by  Capt Len 
#1 · (Edited by Moderator)
This past winter I had my sea cocks and thru hulls replaced. I noticed the ground wire that was attached to the old seacock is not connected. I'm told I should have all my thru hulls grounded. Any suggestions on how to attach the ground wire to the seacock? there are two nuts on the sides but they are too big to put the wire on. The seacock I have is a Grocco 00ASC100LP Bronze-Ball Type Seacock.
 
#2 · (Edited)
With the Groco seacocks there's usually a triangular base. If there isn't a grounding lug (bolt), you can drill into the triangular base (but not through the hull!!!) and then then use a BOTTOM tap to create the necessary threads for the bolt needed to make the bonding connection.

I would think/assume that an 8mm (5/16" diameter.) bolt/machine screw would provide the necessary surface area contact.
You may have to cut, chamfer, and then run any bolt through a (thread) die to properly re-cut the threads on the needed bolt - to make a 'firm'/tight electrical connection. The use of silver bearing conductive compound (similar to that used on SSB/HF radio 'grounds') would be appropriate on that drilled-in bolt.
 
#3 ·
Sea cocks are not grounded per se, however they should be tied in to your "bonding" system which connects to your sacrificial hull zinc....all underwater metals, (struts, rudder, etc) should be part of this system.....this is because sea water creates a battery voltage effect which will eventually eat up the underwater metal, unless bonded to a sacrificial zinc....this way the zinc will corrode and not your sea ****....

I have Grocco's and each sea **** has three mounting bolts that come up through the seacock....all my bond wires are attached by placing the wire (fitted with a crimped eye) over the bolt and then placing a nut over the bolt. If this is not available a fix might be to use a stainless steel clamp around the seacock and have it trap the bond wire (not the best method).....Also to insure a good bond system, a company called Boatzincs at boatzincs.com sells a Corrosion Reference Electrode (looks like a small microphone with a very long cable)....It goes over the side of the boat into the water....its cable is then hooked up to the negative plug of a multimeter... then using the positive probe of the meter, you touch each of your underwater metals....all readings should be the same, about minus 0.9 volts for salt water.....if you get a big deviation on any one of your metals, that bond wire or its attachement point needs to be looked at...(some bond wires corrode inside the crimp over time
 
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