June 2013 Issue
Mailport: June 2013
I read with interest the May 2013 PS Advisor. You advised a reader to crimp a “short, tinned, stranded copper wire” stub onto the backstay using a Nicopress fitting, then attach to this stub with the high-voltage lead-in. While I am sure this will work, the Nicopress fitting is copper (albeit plated), and there is a potential for a galvanic reaction between it and the stainless stay. There is also the issue of what to do if the copper wire is allowed to flex excessively and breaks off, leaving no stub to attach to.
Here’s a solution that has worked on two boats for me: Get a piece of stainless-steel “coated lifeline” sufficiently long to go from the attachment point through the deck—preferably all the way to the tuner. I chose the size that was closest to the diameter of RG-58, so it goes through a commonly available deck fitting. On the backstay, use two or three small, high-quality stainless hose clamps to attach the stripped end to the stay, and then tape over the joint with vinyl tape or better, rigging tape. You’re not trying to waterproof the joint, just make it unlikely to catch lines or anyone’s hand. On the other end, crimp a high-quality lug onto the stainless wire. In my case, for direct attachment to the tuner terminal, or you could make a joint as you described in your answer to a copper high-voltage lead. In either case, you do want to try and waterproof this joint, as you have copper and stainless in contact, and corrosion will happen if salt water finds it.
I was initially concerned that the voltages involved might “punch through” the plastic insulation on the lifeline wire, but I’ve seen no evidence of it in almost 20 years and on two different boats, including several places where the lifeline “lead-in” was zip-tied directly to a grounded stay. On my current boat, I’ve added some of that plastic clip-on “shroud protector” to the grounded lower portion of the stay underneath the lead-in, but that’s mostly to reduce capacitive leakage by spacing the wire a bit further apart.
In regard to your comment about galvanic corrosion: Dissimilar metal corrosion would be minimal and not of much concern in this case.