I have had some trouble with copper water lines, as follows:
1) the copper will work-harden and begin to leak at places where it has to flex and vibrate a lot. It is hard to predict where this will happen. Generally, at each end of a copper line there is a flex hose connected to it which prevents this from happening. The problem is that often, at least in my boat, the flex hose is just slipped over the end of the copper and hose-clamped. Inevitably this leaks. I do not think this was OEM fitment, as it is way too sloppy- I think it came along later on by one of the POs, and I have yet to take it out. Really it should be flared and the right hose fittings put on.
2) Copper will and has burst if water lies in it and freezes. I have had to replace line sections twice. What I learned was that it is impossible to winterize the system using compressed air. The air just bubbles through the water in the low-lying pipe sections and does not push it out. You have to drain the system and then put pink antifreeze through it, which of course means that the water will feel and taste lousy for the first few months of the boating season, until the AF is all rinsed out of there.
3) Copper turns green from corrosion. The prevention for this is to spray the piping, where you can get to it, with Corrosion-X, which has a very long life span and will keep it bright. Unfortunately, all these boats were built before C-X was invented, so they all have green tubing. Cleaning or polishing it is not something I have time for and you can't get to it all anyway. So it stays green.
4) Best replacement alternative? WHALE makes a complete system for marine piping on boats, both hot and cold water, modular, with its own ends and fittings. Also there are domestic water tubing systems made of PEX tubing which are very durable and would easily stand up to marine use. Including, by the way, the areas where it has to run through the engine room which can get to 140F when the engines are shut down and the whole ER heat-soaks. I don't know what Hatteras uses now; my guess is some kind of plastic tubing, especially as copper is very expensive and there is a world shortage of it. Just my guess, though.
5) FWIW, I have had good service out of regular fixtures that you can buy at Home Despot for galley and head faucets. Also the SS flex lines that you get at HD work fine, if you spray them with C-X as noted. Interestingly, sink basins that will fit a boat are hard to find at HD- I have ended up using "marine" ones from Scandvik or BoatUS, because they tend to be smaller and different shapes. Scandvik in particular has SS or painted SS sinks that are very good, but some of the hookup hardware is a little odd. Like- not the same as domestic plumbing stuff. Some adaptations are needed.
6) Finally, and most important: if you are going to R&R the head or galley faucets in your boat, get a basin wrench. The greatest invention of Western Civilization, at least in the modern era of indoor plumbing, is the basin wrench. Best fourteen dollars I ever spent.
