GENERAL STATEMENT ON NEWPORTER GALVANIZED FASTENERS

[bob mitchell]

        My Newporter is a derelict - for example, in the photo below you can see where some idiot filled the bilge with resin, which congealed around the limber chain (which is jerked back and forth to keep the limber holes clear for draining), and basically formed a freshwater swamp in the aft end of the boat. The boat set in freshwater for at least 10 years being neglected, half full of water, in this manner. DO NOT TAKE THE PHOTOS OF MY DERELICT NEWPORTER AS REPRSENTATIVE OF A NEWPORTER THAT WAS EVEN HALF MAINTAINED, MUCH LESS WELL MAINTAINED.          I have dissected my Newporter from stem to stern, paying particular attention to the galvanized fasteners holding the boat together, which I am sure has been painful for all of us, but certainly enlightening as to how Newporters are built. Thank you for bearing with me.  I am sure I might have caused some anxiety so at this time I would like to summarize my findings.  I HAVE NEVER FOUND A BAD GALVANIZED BOLT ANYWHERE EXCEPT WHERE THERE HAS BEEN TOTAL DETERIATION OF THE SURROUNDING WOOD. As an example, here are two photos of the last threaded rod that holds the deadwood together - not something that Newporter owners see everyday! Because of the unusual level of neglect that my boat underwent   I am having to replace the whole apron - it being totally and obviously rotten. The rusted threaded rod bolt top sits in the rotten apron, while the nut and shaft of the threaded rod go through and sits at the bottom of the keel. (You can't see the shaft above the bottom nut because there is an oak batten facing the grove - but it was in good shape). 

      So once more, let me make this statement about Newporter fastenings, including the galvanized boat nails. ANYWHERE THAT THE WOOD APPEARS SOUND I HAVE FOUND THE GALVANIZED FASTENERS TO BE IN GOOD SHAPE. And believe me, I have been through the whole boat.

UPDATE:  The corroded bolt above that was in the apron, after I removed the apron, and banged on the threaded rod a couple of times, turned out to be much better than expected. Probably had several more years to go before failure.

 

[Dennis Gaffney]

On the Sans Souci, the bolt that held on the apron to the deadwood was so rotten that it came to a point like a railroad spike. I removed the bolt with a crowbar and there was a five inch hole where the wood had rotted around the bolt. One of the workers in the yard said that the wood rotted due to a chemical reaction within the wood caused by to the rusting of the bolt, as opposed to the bolt rusting due to exposure from the rotting wood. You are a science teacher, what do you think?

[bob mitchell]

      Yes, that is correct. Specifically in electrolytic action, i.e. a current flowing between differing metals, one with a higher electropotential than the other (bronze has a much greater potential than galvanized bolts), the one with the higher electropotential steals the electrons from the one with lower potential, which leads to deteriation like you mention. Case in point - consider the fate of a sacrificial zinc anode - but in that case there is no surrounding wood

     However, what is really relevant in your question is that during electrolytic action BOTH of the differing metals produce chemical conditions (one acidic and one basic) that destroy the wood fiber surrounding the bolts. (google U.S.D.A. Forest Service Research Paper FPL 229, Degradation of Wood by Products of Metal Corrosion for the excellent, short, report).

    So, Dennis, consider my statement......"ANYWHERE THAT THE WOOD APPEARS SOUND I HAVE FOUND THE GALVANIZED FASTENERS TO BE IN GOOD SHAPE. " The statement in no way implies whether it is the wood's frotting or the metal's rusting that is the cause. The key is that there was salt water (an electrolyte, similar to acid in a battery) in the bilge that provided a path for the electrons to flow (current) between the two dissimilar metals.