[C38] Through-Hull Fittings

[Les]

Hi, Mark,
	I don't.  On ships we used to polish all the bronze in the Navy.  It
didn't seem to bother them.  The bronze and brass will develop that
green Patina just from salt air and humidity.  If you use an area for
storage where you have a thru-hull, that can come off on clothes or
other things and may be objectionable to some people.  As to polishing
covering up a problem, I can't answer that, but I don't think it would.
Most likely if you have a problem, the corrosion would be secondary to
salt build up due to any leakage that was subtle enough to not show up
through polishing, and that would be relatively minor, I think.

	Someone talked about linking all their through hulls together.  In my
limited experience and research, that has limited effects either bad or
good.  Experts seem divided on the electrolysis effects, and the only
other issue would be lightening protection.  Again, there are many
thoughts on what works, but the most accepted view seems to be that
grounding the mast through a heavy wire is the best, providing a "cone
of protection".  I haven't seen any information on linking thru-hulls to
the grounded mast that was definitive.  Lightening deals with something
called skin effect, which can produce odd impedance's making any
prediction about its flow and paths to ground subject to interpretation
without extensive EMF modeling.  It is no small task to perform that
analysis.  If anyone has contradicting information, please provide links
or maybe we can get a copy to post on the C38 website.

Regards,
Les H

 On Tue, 2010-11-30 at 03:46 +0000, TURNER MARK wrote:
> The Goose had all hers replaced with bronze in 2004 when we bought her
> as the purchase urvey recommended two of the originals be changed out.
> We decided as the boat was out of the water to do them all at the same
> time.
> They are all fine with the only maintenance being to operate them all
> whenever e are on the boat.
> Have always had bronze on all of my boats through the year. Early
> plastic ones had a reputation for going brittle over time in Northern
> European waters, but I understand that the new generation of synthetic
> ones are more reliable providing they are rated for below water line
> use.
>  
> Dont know why you'd want to polish them or put 'boots' on them? If
> they are corroding and going geen, it needs investigation and the
> problem fixing. I would have thought polishing them could mask a
> potential problem.
>