Re: Alpha g2 zinc on bearing carrier,mercathode?
Zinc's are used as sacrificial metals and are there to protect the drive exposed to electrical currents due to bad or non-existent grounds. The Mercathode systems is installed to make your boat less attractive so to speak to stray electric currents from other systems. Boat (A) could have a perfect electrical system but may be damaged by boat (B) which has a bad ground system. A boat which has been fine for many years with no effects due to stray currents may need to have additional zincs or additional anodes from a Mercathode if metals are changed. Changing from a aluminum prop to a stainless steel will increase the attraction to currents.
My single bravo 3 (stainless steel props) showed signs on the drive housing behind the props every year when I pulled it out for the season. The marina is a modern setup but new zincs and repainting didn't help much. Using the Mercury prob and a digital meter I determined the field current being transmitted by my Mercathode was not sufficient. I installed additional Mercathode and 2 additional anodes, field current was increased and the problem stopped.
If a boat is in the water but not plugged into shore power, if a boat is kept on a trailer except when in use, then you probably can get by without need for additional zinc's or a Mercathode.
