ok, i read though Nigel Calder's (Boatowner's mech. and electrical manual) discussion on grounding, corrosion, and lightening protection.

here is my condensed conversation:

why you want grounding:
1. if you have AC (shore power), you want a direct path to ground for your boat, in addition to the ground protection afforded by the shorepower connection. The reason for the redundant system is to make sure that there is no reason you should be electrocuted when playing with/using AC, so provide for your own ground, for your own safety.

2. for lightening, you want to bring the potential of all metal down to the potential of the water (in theory, making you no more of a target than the water around you). this should include, the rigging, the AC ground, and the negative of the battery.

3. your zincs should be grounded such that when connected to shorepower, they are the least noble/most anodic thing electrically connected to the common ground. if the zincs are not connected to the ground, but the bronze thru-hull is connected, the most anodic thing on the circuit electrically, are the bronze thru-hulls. bad.

why grounding is a pain:
1. if you are connected to shorepower, the ground from you and the ground from that aweful Hunter 38 next to you on the slip will create a galvanic cell (battery). the boat with the least noble/ most anodic stuff in the water will win out, and that might not be you. unless you have attached zincs to the ground and the water.

2. the obvious, its a pain to install a grounding plate. besides the new paranoia that there are more leaks, you have to make sure that the ground shoe is correctly connected to the gound, and that corrosion hasn't negated your electrical connections to it. and oh by the way, make sure that it isn't eaten away by ensuring zincs are electrically connected.


and by the way, most battery chargers connect the negative of the battery to the ground of the AC wires. so if they negative of the battery is connected to the thru-hull, you might have just also connected to the ground of that crappy Hunter and it's zincs, etc etc etc. so you might as well ground it correctly to begin with, lest you fool yourself.

so grounding to the thru-hull alone is just inviting corrosion.

and grounding to the lead ballast does nothing. (this was probably done because that PO thought that it was electrically connected to the water, or plain exposed to the water.


so, for you guys with OB's how did you electrically connect your zincs to the ground of the boat?
for those with nifty ground shoes, where did you put your zincs? and how much of a pain is it to install/maintain?

it would be really really cool if they made a zinc thru-hull strainer (to replace the bronze strainer on the head intake).

ok, i am continuing to plow through Calder's book, and will keep the populous posted to any more exceptions to the rules.

just adding to the confusion......