I thought I knew everything about electricity <grin>, but was surpised about an electrical measurement I just made. If I put a probe in the salt water (floating the boat) and another probe on either stay or shroud, I see .7 volts being generated. This is in the very low, milliamp range. Also weird is that the sea is positive and the rig is negative. I do remember in chemistry class making a similar battery, but didn't expect it here.
In case you're wondering, I disconnected shore power completely (it has a galvanic isolator I made, but is not a factor here) and turned of the main DC breaker, no difference.
Just for the fun of it, I measured several Catalina 42's on my dock. They all generated electricity, some .4 volts, one at 1.0 volts. Some had a voltage from the rig, some didn't, strangely their positive voltage was from the pulpits (I don't understand how this happens). I checked other length Catalinas, they all generated electricity.
It appears from the different positive sources is that some boats have the rig grounded (no voltage from stays/shrouds, grounded to the sea), some are not grounded.
Based on this, it would appear our zincs disappear quickly, but, at least on my boat, they last close to 6 months. The last time I hauled out, there was no galvanic action on the prop or shaft.
Has anyone else noticed such a behavior?
In case you're wondering, I disconnected shore power completely (it has a galvanic isolator I made, but is not a factor here) and turned of the main DC breaker, no difference.
Just for the fun of it, I measured several Catalina 42's on my dock. They all generated electricity, some .4 volts, one at 1.0 volts. Some had a voltage from the rig, some didn't, strangely their positive voltage was from the pulpits (I don't understand how this happens). I checked other length Catalinas, they all generated electricity.
It appears from the different positive sources is that some boats have the rig grounded (no voltage from stays/shrouds, grounded to the sea), some are not grounded.
Based on this, it would appear our zincs disappear quickly, but, at least on my boat, they last close to 6 months. The last time I hauled out, there was no galvanic action on the prop or shaft.
Has anyone else noticed such a behavior?
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Norm Perron, Hull #600/2 cabin, Aphrodisiac, Marina del Rey, CA
Norm Perron, Hull #600/2 cabin, Aphrodisiac, Marina del Rey, CA
