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From: (no name) (no email)
Date: Wed Aug 18 1999 - 21:17:03 EDT
I intend to complete my lightening protection system on my 39' glass/ply
trimaran when I haul it next week...I may be a little late doing this, but I
wanted to see if anybody had comments/suggestions (not likely, since we're
such an un-opinionated bunch<grin>) before I "make it so."
Anyway, I recently installed an ion dissapator and now need to complete the
path to ground/sea. Please, let's not debate the dissapator issue, I find
the theory behind them sound and have already made my decision on that point.
The issue now is the grounding plate(s). A dissapator should (in theory)
prevent a strike, but the system should be designed to handle major current
in case that doesn't prove to be the case.
A path straight down my aluminum mast is less than desirable (for me....I
suspect the lightening likes it) because the mast is supported by foward
crossbeam/main bulkhead. Since there's no way to continue the the conductive
path down without obstructing the passageway foward or having fairly tight
bends in conductors running to either side of the passageway, I'm leaning
towards trying to make the rigging a very appealing path for the electricty.
I don't like the idea of inviting it into the cabin on the mast and then
encouraging it to arc to ground inside the cabin, and I like the idea of
trying to keep it on the outside!
To this end, I'm considering running solid copper wire (4gage or so) from the
bottom of my cap shroud chainplates (on the outside of the amas) to 4' x
1or2" x 1/8" copper strips mounted below the waterline. I'm also considering
connecting the head and back stays to copper strips at the bow and stern.
Additionally I think that a strip admidships on the main hull (or perhaps one
on each side of the main hull) connected to the lower shrouds and mast base
is a good idea. The conductors going to these will not be real straight, but
hopefully, a very large portion of the current would be handled by the outter
rigging. And it doesn't seem prudent to leave these as "dead ends" which
would invite arcing.
The copper strips would not be painted or faired into the hull and should
provide plenty of surface area and lots of "edge." They would have one bolt
that penetrated the hull to allow for connections from the inside (except for
the two on the amas).
Comments appreciated.
An issue that I have not really considered in depth are the galvanic problems
this may create. Until now, I have luckily been able to avoid straining my
brain on that issue since the only metal on my boat in contact with the water
is the head (through the intake hose), the rudder post, and the engine -- but
only when in use (retractable). But then again, it's typical of me to do
someting without thinking everyting through! I guess I'll burn that bridge
when I come to it.
Thanks,
JP
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