What is causing this ?

[GregF]

If he has a metal transom on the motor bracket, the hull will be solidly grounded. That in itself is not a problem but then a second path to the water can be troubling.
The engine itself will have bonding jumpers so all parts are grounded but that is to avoid electrolysis between the various parts.
If you are poking around looking for stray voltage, I would start with the DCV 50 scale and then try the 10 scale if it bumps at all.

I am still skeptical that what you are seeing is electrical.

[Redneck_Randy]

Thanks guy's. I will use those settings tomorrow to see what comes of it. Sure wish you guy's were here to see it with your own eyes.