S/V Argo-Pacific Seacraft
Join Date: Oct 2007
Location: Baltimore, MD
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Re: Bonding and Grounding of Underwater Metals
I guess my specific question is: How is your Pacific Seacraft bonded?
The professional marine community very clearly articulates the need, and requirement for, bonding of underwater hull elements. It's a safety issue; everything on the boat should be at the same potential. This is an ABYC (American Boat and Yacht Council) requirement for yachts and motor boats, a US CFR (United States Code of Federal Regulations) requirement for passenger and commercial vessels, and a design and operational requirement for vessels of the U.S. Coast Guard and U.S. Navy.
I'm not terribly concerned about the lightning protection, save for the fact to increase the bonding wire size from 8AWG to 6AWG where bonding conductors are installed as a secondary or parallel path for the main lightning conductor.
Hmm. Can of worms. I think think this is one of those questions that you'll get different opinions on. I think most of your fittings should NOT be bonded together (they should be kept isolated). How's that for disagreement already? It depends on what you want to do it for. Is it for protection from a lightening strike or to prevent corrosion from stray current in the boat or from stray current in a marina? These require different approaches, but I think none results in bonding everything together. For example, if it's lightening you're worried about (to protect you if not your electronics, which can probably only be protected by the gods), you'd want to bond things near the mast. If boat current is a problem, fix the problem. If marina current is the problem, bonding everything could just make it worse. Unless a previous owner has changed something, your boat may be bonded appropriately right now. Don Casey's boat fixing book has a section on this sort of thing. But, again, I think you are going to get different perspectives on this. (Like my recent question on lifelines: some say wire, some say rope, and never the twain shall meet.) As for my 37, which I'm confident is still 'bonded' as it was from the factory, almost all of the underwater fittings are NOT bonded together.
S/V ARGO - Pacific Seacraft 37 Hull No. 309