Originally Posted by EwenT
If you observe any other interesting features on your electrode surface, however subtle, I would like to hear about them. If I was involved in a forensic analysis and had your electrode on hand I would examine it with a microscope, but do not wish to influence your observations and so will not say what I would be looking for. Also, any features on your saildrive
, prop shaft or propeller
are relevant to the current
flow through the engine
It has been almost 4 years now since our strike, and the electrode has been in use (in the water) almost continually since. However, I just took a magnifying loupe to it and examined it very closely.
4 of the 18 edges machined into it have either round pits missing from them or ~1/4" long sections carved out of them (like someone dulled a knife edge against a stone). It takes a magnifying loupe (10X) to see this, as they are not readily apparent to (my) naked eye.
None of the flat surface shows any damage - only the edge surfaces. And the edges that have the damage all seem to be the edges closest to the main body of the electrode. This is hard to explain, but if you look at the picture of the electrode I posted, each machined ridge has 3 edge surfaces that I will call "left, top, right", as viewed on end.
In our case, 4 of the "right" edges have the damage - there is no damage to "top" or "left" edges.
I cannot get a picture of this because the camera
won't focus that closely and blowing up a further picture really doesn't work well.
These marks could have always been there, or could have occurred through erosion/corrosion/impact after the strike, or could have been caused by the strike. Unfortunately, I did not examine it this closely immediately after the strike.
As for the saildrive
, it is electrically isolated from the engine
by teflon bushings and gasket
, and the propeller
is electrically isolated from the prop shaft by a rubber hub - I have observed no damage to the drive or prop. I suspect either the engine block absorbed the residual current
bouncing in the system or the current was passed to the water
through the cooling