[C320-list] Lightning

[Jack Brennan]

Hi Tom:

My 1998 320 has a thick cable bolted to the mast support and connected to a keel bolt. In theory, the mast is the lightning rod and the massive keel is the ground stake. However …

Lightning is kazillion volts and basically does what it wants to. It might run straight down through the keel, or maybe it does a side flash to other metal such as the oven. We are lucky to have Marelon through hulls because they won’t attract side flashes and melt, the way bronze could.

I live in Florida, the lightning capital of the world, and I have had two close brushes with lightning in 40 years of off and on sailing. That should tell you something about where it should be on your list of worries.

In the first, I was in my 19-foot sailboat about three miles off Fort Lauderdale, making a late return at night from the Keys. I pulled down the sails and lit a cigarette (I smoked back then) while lightning bolts struck all around me for about 30 minutes. I could see them hitting the water, but none hit me. Scared the hell out of me.

The second was about seven years ago. My wife and I were scrambling in as a summer thunderstorm arrived in Hillsboro Inlet from the Everglades. I was dropping the anchor in 30-knot gusts when a bolt struck about 40 yards from us in the harbor. It knocked out random electronics in my Bristol 30, but I didn’t feel anything.

So my rules are take down the sails, anchor if you are in restricted waters, lock the wheel to protect the rudder, go below and stay away from metal. I also shut off the electricity and put all cellphones, computers, portable GPS’s, handheld radios, etc., in the oven.

The reason for that is something called the Faraday Cage. Anything enclosed in metal won’t be affected by lightning. It’s why the 747 doesn’t go down when it is struck by lightning. If it does get bad, you have the ability to call for help.

Hope this helps.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.
Dolphin Cruising Club of Tampa Bay





Sent from Mail for Windows 10

From: Tom Grass
Sent: Sunday, December 13, 2020 10:12 AM
To: C320-List at catalina320.com
Cc: Tracy Grass
Subject: [C320-list] Lightning

Wondering about lightning protection on Catalina 320 boats?  I don't
believe they come grounded (mast to keel) from the factory - wondering what
the members of this forum have done in an attempt to minimize the impact of
a possible lightning strike?

Also what is the collective opinion of installing a Forespar Performance
Products Forespar Lightning Master™ - Static Dissipater
on your mast?  We're planning on sailing down to the Chesapeake Bay and
perhaps to the Bahamas in 2021 - just preparing in advance.

Thanks,

Tom and Tracy Grass
Bucket List
2008 Catalina 320 MK II