Measure the shaft, motor cooling water intake, motor block.
You have a value .210 volts at what you call "bonding wire." You say it starts at the keel bolt. Where does go from there and where does it eventually end? Do you know if there is a zinc bolted to the keel on the outside?
Are any of the items on the list (apart from the keel) connected by a wire? This is usually a green wire that goes from item to item and ends at the motor block or an external zinc thus the items are said to be "bonded." )
I assume the items you measured are not submerged in bilge salt water - which could connect them together intermittently. If no bilge water submersion then - so far
The values suggest the through hulls are high quality bronze, the items are not bonded, the items are not exposed to DC current, and the items are not players in zinc loss because they are not connected to the zincs that are wasting.
The motor/shaft/cooling water intake are connected to the wasting zincs and these measurements will be the most helpful. Record the results with shore power cord plugged in and shore power unplugged. Also with battery cable connected and not connected - that includes house and start batteries.
Charles
You have a value .210 volts at what you call "bonding wire." You say it starts at the keel bolt. Where does go from there and where does it eventually end? Do you know if there is a zinc bolted to the keel on the outside?
Are any of the items on the list (apart from the keel) connected by a wire? This is usually a green wire that goes from item to item and ends at the motor block or an external zinc thus the items are said to be "bonded." )
I assume the items you measured are not submerged in bilge salt water - which could connect them together intermittently. If no bilge water submersion then - so far
The values suggest the through hulls are high quality bronze, the items are not bonded, the items are not exposed to DC current, and the items are not players in zinc loss because they are not connected to the zincs that are wasting.
The motor/shaft/cooling water intake are connected to the wasting zincs and these measurements will be the most helpful. Record the results with shore power cord plugged in and shore power unplugged. Also with battery cable connected and not connected - that includes house and start batteries.
Charles