I know what a zinc anode does, but I can't clearly determine if it must be in contact with the metal or if being suspended in solution would do the trick as well. First off freshwater boat only. I bought a pair of SS aftermarket manifolds. They use a pencil anode and one has broken off inside and I cant get it out. Would it still work floating around in their or does it have to be touching the manifold. In addition if it must touch the metal its protecting, then why is it inserted into a brass plug? The 3/8 pencil anode screws into a brass plug that screws into the stainless steel manifold.