Question: I’m the proud owner of a new C&C 101 sailboat that I plan to race and cruise with my family. Last weekend I was prowling around in the bilge area and I came across the bare copper wire you can see in the bottom of the photo.
It is single-strand copper and gets attached to a buss bar that you can’t see. Everything I’ve ever read about boat wiring says that single-strand wire is a not meant for marine applications, and many articles also have talked about boat wiring and the recommended insulation properties for the wire. What’s up here?
Answer: The short answer to your question is: Old habits die hard! Your boat was built in the same plant as all of the new Tartan Yachts, and they do exactly the same thing.
What you are looking at is one of the boat’s bonding conductors, and it is attached to the grounding bus bar. The practice of using un-insulated copper single strand has a long history and is not exclusive to this builder; many of the older Hinckley Yachts used this technique. Some other builders used un-insulated flat copper strip back in the day.
Does it comply with current industry standards? Not really.
You are quite right that the standard today is to use only insulated wire. Current industry standards also call for multi-strand conductors. That said, since the bonding conductors are not normally carrying any electrical current there certainly is no electrical shock hazard present here. As for the single strand vs. multi-strand issue, it seems that both Tartan and C&C have decided that since they really haven’t demonstrated any problems with this type of installation, and it's been used for decades at least on the Tartans, why change?
The bare copper will indeed develop a nice green patina over time (see a related post: Does Copper Need Coating in the Marine Environment?) but that will not affect the wire’s conductivity. The bottom line on this is, don’t worry about it -- the system will operate as intended, for many years to come.