Regarding
the zinc on the prop, I've seen it mentioned that this is unnecessary
due to the AMEL-style bonding system, with everything bonded to
everything else. However, as I currently understand it, the reason for
the zinc on the prop, is because with a stainless prop shaft attached to
the dissimilar bronze of the prop, and because this is underwater, this
creates a galvanic couple. So, to minimise the potential effects of
this galvanic couple, it is best to place a zinc as close as possible to that underwater connection. And also, minimise the opportunity for adverse effects should there be a failure, or deterioration, in the bonding circuit between shaft -to- transmission -to- bonding-circuit -to- rudder-post -to- rudder-zincs connections.
Happy to be corrected. However, in the interim, I personally would be placing a zinc on the prop/shaft to take all possible steps to minimise the potential for galvanic corrosion of the shaft or the prop.
