Post #61
Quote:
There would not be any corrosion on the unconnected middle boat. Any current in the water would dissipate a very short distance after the source. The boat would have to be connected to shore power to realize any effect from the others or the marina's wiring.
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If the victim boat is not plugged in to shore
power and
if the victim boat has some or all of its underwater metal components bonded, and
if the victim boat is in the
electric field set up in the water column by Boat #1, Boat #1 is plugged into shore
power, then the stray current will enter the victim boat's bonding system via the bonded underwater fitting closest to the leaking boat, use the victim boat's bonding system as the preferential conductive path (copper is much, much more conductive than seawater) and then leave the victim boat at an underwater bonded fitting close to the third boat that is connected to shore power. Stray current damage will occur on the victim boat's bonded underwater metal components.
If the victim boat is unbonded, then the same scenario is played out, only involving the victim boat's prop, shaft and shaft anode.
Quote:
Any current in the water would dissipate a very short distance after the source.
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This is not correct. Remember that we can shift the potential (against a reference cell) of a bonded metal
thru hull -200mVDC, or more, when the
thru hull (e.g.,
anchor wash down source) is fifty feet from a plate zinc anode mounted on the transom. And the zinc anode only provides about -1000mVDC of potential. If a boat is leaking 12VDC into the water column, its effect will be noticeable some distance from the injection point.