[Public-list] Through-hulls & Zincs

[Rick Leach]

RE: Whitby's 1/2" through-hulls

"When the washer corrodes away, you have nothing left holding the 
pipe in place, except that it has been there for years."

I never considered leaving the one remaining Whitby "home-made" through-hull in place once I realized what I was looking at.  To their credit though, once removed it was still in remarkably good shape.  I have to believe that there are some horror stories out there though.

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RE: Prop/shaft zincs

"Another solution that I used was to buy a nut/housing for 7/8" shaft that 
the bronze housing has a slot in it for a cotter pin and the zinc fits over 
the housing. I bought mine many years ago at West, The only downside is that 
that there is not as much zinc and I find that I need to change the zinc 
part every year (maybe I should talk to my neighbor about his extension 
cords which often lay in the water)."


I have used the prop nut cone/zinc unit with good luck for years.  But I do inspect and clean at least quarterly using scuba.  Mike's comment about his neighbor's cord makes a good point.  Many marinas are "hot", meaning that very often people will unknowingly create destructive current paths through their boat's hardware and equipment (aluminum outdrives are often the big losers).  Onboard AC systems that are poorly designed, installed and/or maintained are often the worst offenders, due to the significantly higher voltages.  Without proper isolation the common ground wire circuit of the marina's power system can effectively put you in the same circuit as God-knows-what.  I don't even have an AC system, but I noticed that the life of my zincs tripled when I moved from a slip out to a mooring.  Obviously, somebody in the vicinity of my slip had some kind of problem.  I guess the lesson for me was to check the zincs often (and never own an I/O).



Rick Leach
S/V Sugar Magnolia, #121
Monterey, California