[C320-list] Lightning Storm Damage

[warren updike]

I'm way behind in list postings so at the risk of repeating what might have
already been said I'll add my two bits.

The subject of lightening protection is a thorny one.  For those using auto
battery cables to ground the mast by the shrouds you could be inviting a
problem.  Do more research on the matter and decide for yourself.

The dissipative area for submerged contact should be a copper plate not less
than 144"sq.  The cables should be of a substantial gage (I don't have the
details,) and bolted to the mast above the deck.  The cables should lead to
the copper plate overboard with as direct a route as possible with as little
bend as possible.  There is much more to consider.

Even if you are not connected to the shore power, but are near enough the
object of a strike, the electromagnetic pulse could induce a current in your
boat wiring sufficient to fry your more sensitive equipment.  Grounding is
not necessarily assured protection.

Also, investigate the concept of the "Cone of Protection."

I'm not an engineer or any expert in this area.  I've just done enough
reading to know how much I don't know.


Warren & Pattie Updke
Catalina 320, #62, "Warr De Mar"
Middle River, Chesapeake Bay



-----Original Message-----
Quentin,

We sail at  Niagara-on-the-Lake Sailing Club, we use automobile jumper
cables attached to the shrouds and then overboard to the water if caught in
lighting or at shore. Many sailors on the south shore of Lake Ontario us
this method  believing it is added protection, although the is very little
one can do to fully protect the boat.

Tim O'Connor
Kinsail  # 592

-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Quentin Murphy
Sent: Sunday, June 15, 2008 9:08 PM
To: C320-List at Catalina320.com
Subject: [C320-list] Lightning Storm Damage

Last week lightning appears to have hit the mast of a C-350 at our club and
did considerable damage inside.  There is soot everywhere and every
electrical and electronic system fried.  Anyway, about six other boats also
suffered in the vicinity, supposedly through the shorepower system.  For
example, a powerboat two slips away had its bow  thruster damaged and
battery charger blown.  Are there any precautions we can take other than
unplugging our shorepower cord prior to thunderstorms?  In Toronto, we have
many thunderstorms during summer, although this year seems much worst, but
this is the first such instance of damage I can recall in our vicinity.

Quentin Murphy
Celtic Knot #667