Paul, thanks for posting the links. I am going to repost, and modify the replies I made on that thread.
We have been in a number of lightning storms in various boats. In the
C Dory we would disconnect the electronics--antennas, grounds, transducers and posative and negitive power cables. Remember that lightning can come thru the water in a near by strike.
Anchor if at all possiable. Put antennas down. Stay away from any metal in the boat. A ground plate, lightning diffuser etc would do little if any good in a C Dory or TC.
We have had direct strikes on a boat with wooden masts and shrouds which were directly grounded to the water with chains--and the only damage (all electronics disconnected)--was to diodes in wind instruments. This mast was the tallest item in a cove in Yugoslavia, where a dozen or so sailboats were anchored. We had "St Elmo's Fire" in the rigging. There were over 60 strikes visible in this cove area in one hour!
Wikipedia paraphrased St Elmo's Fire::
Luminous plasma is created by a corona discharge from a rod-like object such as a mast; An electric field around the affected object causes ionization of the air molecules, producing a faint glow easily visible in low-light conditions.
. This boat had a direct connection from the forestay to a bob stay into the water. All of the upper shrouds, were connected to a weldment at the masthead. The chain plates were notched so I could put 3/8 chains thru the notch and directly into the water. Same for triadic and mizzen mast rigging. We did not have any direct strikes, but lost some of the diodes in the wind instruments which are on top of the mast. Other boats in that cove had direct strikes.
On our Cal 46 boat, with 57 foot high aluminum mast, we had a fuzzy dissipator bolted to the masthead. At the base of the mast there was an aluminum weldment about12 feet long and 12" wide which I tied to the internal lead ballast (capacitance connection), direct copper tubing bolted to a 1 sq foot plate of copper outside the hull, from the base of the mast.---There was a direct strike to a power boat's VHF antenna, about 50 feet away. A lobe came thru the water, and took out the diodes in the alternator and regulator of the Cal 46. This allowed the battery charger to be continuously discharging thru the bonded metal under water. When we got back with out "new" trawler in about a week, the 24" x 24" prop had about 50% of its mass destroyed. The prop shaft was destroyed, as was the rudder shaft (3" thick wall aluminum pipe) and all thru hulls. My 65' hight Ham Radio Tower was about 75 feet from the sailboat, and directly grounded. (about 12 feet above the water level, so that tower was about 20 feet taller than the sailboat mast and it sustained no damage.)
The buyer of the Cal 46 had 2 more major lightning strikes with extensive damage in South Florida during the 20 years he owned and full time cruised the boat. I don't know if he had modified the "Lightning protection"
There are anumber of good web articles on lightning--espicially those by University of Florida.
I have been hit by very small lobes from lightning strikes 3 times. The first was when I was In 4th grade in Calif standing next to a window. A lightning strike hit an object on the nearby playground and jumped to a very small lobe thru the window. The second was when back packing in the Sierra, and there was a strike to a tree nearby. The last one we were on a friend's trawler--and on the flying bridge. I told the skipper we should shut down and get below in a very bad lightening storm. His response was to get as close to a sailboat going the same direction...I mean only a few feet from his bow to the sailboat's stern... (I was hiding out of embarrassment)
A strike hit the sailboat mast--and all sorts of bad things happened to this boat--fortunately we didn't run it over when the sailboat engine stopped...
A lobe of this strike hit the Bimini frame next to me, and a small arch jumped to my shoulder and then to Marie who was sitting next to me. No damage to either of us. But the skipper got the message--and we went below and drifted until the storm was over...
A direct strike will cause burning in multiple patterns on a person. Clothing can burst into flame, cardiac arrest, brain damage and instant death may occur (some patients can be resuscitated--so CPR is always indicatedI).
For several years I was in charge of "safety" during regattas at Pensacola Yacht club. In events such as the Optimus Pram national championships, we had 20 safety boats plus a number of race committee and coaching boats. All of the power boats had vhf radios where we could relay safety messages. This is where we used th 30 mile rule. We had a source of direct weather information at NAS Pensacola weather / Control Tower. We had one of the air traffic controllers at PNS airport, And we had one person who was continuously watching weather channels which showed lightning strikes, plus a sport fisher with his 72 mile radar constantly monitored. If we had any lightning within 30 miles, we immediately began to get the racers off the water.[/b]
Be careful and be safe. No visible damage to the trailers. I believe what we saw was a lobe to the ground, and the primary strike to a Safety light in the neighbor's back yard. She had the light vaporized, plus it took out one sub panel of her house electrical system. The rest of her lights worked. But, I suggested that she have an electrician inspect and test all of the circuit breakers. The wiring to the security light, and light will have to be replaced, plus the burned breakers. She was lucky--at the time of the strike, she was sitting on her back porch with friends, and was not injured.
