Posted by Bob on July 11, 19103 at 17:17:12:
In Reply to: Re: external hull grounding plates posted by ken on July 10, 19103 at 06:18:38:
: : We are building a Double Eagle in timber. The Glen L instructions calls for a 1 sq.ft copper external grounding plate. can any one explain to me what its purpose is and why here in Australia, no fibre glass boats ( the Double Eagle is sheathed in fibre glass ), are fitted with such grounding plates.
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: That plate they speak of is used for 'bonding' the fittings in the hull. It helps to prevent electrolysis corrosion of metal parts in the hull.
: A good question would be why has sacrificial zincs become more popular than this system?
Thoough use of bonding circuits was recommended for a few years, it has been very well discredited for wooden boats, which this will be at heart despite the glass skin. Electolytic products damage the wood and bonding doesn't spare the metal parts. Good bronze will be fine if left alone. Stainless needs lots of help from a zinc connected directly to it (not a general bonding of everything). Some radio antennas need a ground plane, but not all, and some work fine gounded to the engine water through hull. Some electrical installations, but not all, are grounded to a plate as well but those are separate issues from bonding.