We love our floating home lifestyle, but we often find ourselves concerned with subjects the landlocked know nothing about, like freeboard, macerator pumps, and the health of the hulls on which we float. West Pier neighbor Court Mast and I talked at length about hulls as we recently spent time doing a little maintenance on my solar batteries.
Court has made a study of hull health, and he has burrowed deep into the science, the debates, the mystery, the history, and the cast of characters around the decidedly unsexy subject of… sacrificial anodes.
Like most great stories, it goes back centuries — two, to 1824. Sir Humphry Davy had zinc plates installed on the copper sheathed hulls of British naval vessels. Since that time, zinc anodes have been used on boats to protect electrolysis from attacking bronze propellers, shafts, struts and through hulls. Or in our case, the web of steel rebar that nets our concrete structures together.
That bit of history comes from “Zincs and Your Concrete Barge,” by Dan Goodman, an article that appeared 20 years ago in the Floating Times. Goodman goes on, “Zinc is a less ‘noble’ metal which, if put in contact with more noble metals, acts as a sacrificial element drawing corrosive electrical charges away from essential hardware,” like steel rebar.
Goodman’s article is part of Court’s research on the subject. The story unfolds over time. Ted Eitelbuss, late of Issaquah Pier, whose barge maintenance and repair were essential to our community’s hull health, began installing sacrificial anodes on our barges around 2000 until his death in 2018. He pioneered adding zinc blocks to corners of barges by welding copper wires to the rebar and hanging the blocks off the wire-ends and into the saltwater.
While Ted relied on intuition and more than a little trial-and-error, he didn’t measure the anodes’ electrical efficacy. In 2008 the FHA, then led by Stan Barbarich, commissioned CorrPro, a leading corrosion firm based in San Leandro, for a study of our barges’ electrical properties. Seventeen barges were tested, and the electrical results confirmed that the rebar’s ongoing corrosion from saltwater was cracking the concrete in the hulls. Electrical conductivity was recorded throughout each barge, end-to-end. Ted’s sacrificial anodes were recommended as the best method to reduce or nullify each barge’s ongoing corrosion.
Sadly, the CorrPro study was largely forgotten and Ted’s anode advocacy died with him in 2018. Confusion arose during a 2020 online forum featuring Ian Moody and other presenters. They posited that anodes had no effect because a hull’s rebar rods are not welded together. Based on the erroneous information, a number of homeowners set about removing the anodes from their hulls, and hiring Court to do the dirty work.
Court started his own study to determine the correct course of action. He got himself a marine corrosion test unit from Electro Guard and began using it as he replaced his own anodes and some others including mine. He sought out the expertise provided by Spaulding Marine Center with a class on corrosion taught by the authority Malcolm Morgan, complete with charts of electrical targets for steel in concrete hulls.
Pete Hudson, recent FHA president, joined with Stan Barbarich and Court in a search through the FHA’s printed archives to find the original CorrPro study from 2008. In December 2024, Pete found the study buried deep in the FHA’s website. FHA members will find it as a PDF entitled “Cathodic Protection Evaluation and Preliminary Design Survey.” Look for it under Resources/Maintenance once you’ve logged into the site.
Bottom line: The zincs work and our barges need them.
So, if like me, you once wondered what those little charms were that dangled off the bracelet of concrete on which we depend, now you know. And thanks to neighbors, you have ready access to lots of info. Someone else has done the thinking (or zincing!) for us.