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Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

Lightning grounding

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Bruce Baker
Captain

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USA
402 Posts

Initially Posted - 07/22/2002 : 07:41:39

Does anybody know if C-25's or C-250's come from the factory with any grouding against lightning? I take my swing keel boat out Tuesday nights to race in a little series on the Potomac, and thunderstorms are pretty common in Washington during July and August. Do I have any built-in protections? Should I be thinking about an upgrade?

Thanks,
Bruce Baker
"Yee Ha"

Edited by - on

cathluk
Admiral

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USA
513 Posts

Response Posted - 07/22/2002 : 07:54:43

My C250 does not have any lightening grounding. There is a good article on the subject in the current issue of Sail magazine.

Cathy
"Blown Away"
'97 C250WK #253

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/22/2002 : 12:41:08

Bruce: There have been extensive discussions on this topic on this forum--you may be able to hunt them down. I have referred people to a U. FL site (don't remember it now, but you can probably find it on Google) that discusses extensive research on lightning and boats, with very undifinitive results.

The net of it is, Catalina and most builders put nothing in their boats--probably because anything they do is as likely to fail as to work, and would therefore expose them to liability.

Among the arguments are:

- Jumper cables from the bases of the shrouds will direct the bolt down the shrouds and into the water. Trouble is, a small stainless cable is nowhere near the conductor that a big aluminum mast is, so that's questionable.

- A large copper strap from the mast step to a keel bolt will pass the energy to the water. Some suspect that it will also attract a strike, which may be worse than not doing so.

- The copper strap or cable should go to a large (square foot or larger) copper plate on the outside of the hull--meaning a new hole in the bottom and a carefully engineered connection.

- A grounded device with copper streamers at the masthead is perported to reduce ionization in that area, shielding the mast from strikes.

- A cabintop-stepped mast is far enough from the water, with several layers of insulation in between, that it does not tend to attract lightning. As evidence, many boats get their electronics fried by very close strikes to the water that apparently don't hit the boat's rig. I know of several such cases, but of nobody who has had a direct hit. (God--I shouldn't have said that! <img src=icon_smile_shock.gif border=0 align=middle>)

- Boats in salt water are thought to be in somewhat less danger because salt water conducts, and therefore attracts and disperses the charge better. Boats in fresh water may be somewhat more attractive to lightning, and may be more affected by near misses. (See the U. FL site for a better discussion of this.)

- Doing something but doing it wrong may be worse than doing nothing--in that once lightning starts testing your system, it could cause a lot of damage (such as blowing a hole in the bottom) showing you the system's weaknesses.

Note: These are all "arguments" and there are plenty more arguments to go around, but no definitive conclusions. See what the experts say, and you might want to get somebody like a marine surveyor to at least give an opinion on whatever protection you're thinking of adding.

I, personally, use weather forecasts, NOAA, the AM radio (listening for static), and my eyeballs to keep myself from being out in an electrical storm. If my boat gets hit unattended at the dock, nobody will be hurt. <img src=icon_smile_blush.gif border=0 align=middle>

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette "Passage" in SW CT

Edited by - dave bristle on 07/22/2002 16:22:24

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Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 07/22/2002 : 16:28:55

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
My C250 does not have any lightening grounding. There is a good article on the subject in the current issue of Sail magazine.

Cathy
"Blown Away"
'97 C250WK #253
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I would second this recommendation...It covers the topic very thoroughly.

Duane Wolff
"The Flying Wasp"
C-25, #401 std,sk
Chief Measurer C-25/250 National Assn.
<img src="http://im1.shutterfly.com/procserv/47b1ce23b3127cce9b043565af3d0000004010" border=0>

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/23/2002 : 11:29:13

Here's the U. FL link...

http://www.thomson.ece.ufl.edu/lightning/

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette "Passage" in SW CT

Edited by - on

jellyfish
Navigator

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USA
171 Posts

Response Posted - 07/23/2002 : 11:54:16

the old addage "damned if you do and damned if you dont" seems to apply here from everything Ive read. and here is a personal believe it or not. my C25 tall rig was sitting right next to a mac22. I mean in the slip right next to me. the mac22 with it's much shorter mast took a hit and burned the electrical system and the interior cushions. I wasnt touched. go figure!

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/23/2002 : 14:44:35

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
the mac22 with it's much shorter mast took a hit and burned the electrical system and the interior cushions. I wasnt touched. go figure!
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
Hmmm... Let's see... The base of your mast is maybe a foot or more above that of the Mac 22, and your bottom is maybe a half a foot deeper at the mast, with much heavier fiberglass (insulator)... Sounds like the shorter distance "won" from the lightning's viewpoint. But if he hadn't been there, guess what? <img src=icon_smile_dead.gif border=0 align=middle>

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette "Passage" in SW CT

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jellyfish
Navigator

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USA
171 Posts

Response Posted - 07/23/2002 : 15:15:59

Dave, just call me stupid but, I fail to see your logic! please clue me in. I know that lighting takes the path of least resistence and it usually takes the shortest path to ground. Enlighten me.

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Steve Milby
Past Commodore

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USA
5937 Posts

Response Posted - 07/23/2002 : 16:04:42

Bruce,

The long-standing practice of our sailing club is to stop a race whenever thunder and lightning are in the area, and we all go back to the docks until it passes. Does your club continue to race during thunder and lightning storms? Of course, the tradition is that the Captain is responsible for the safety of the boat and passengers, so, if the conditions cause you to believe it is unsafe to continue racing, then you should drop out, regardless of what the others do. After all, it's only a sailboat race.

Steve Milby "Captiva Wind" C-25 T/FK #2554

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jellyfish
Navigator

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USA
171 Posts

Response Posted - 07/24/2002 : 11:44:35

I just got back from the mailbox and my copy of Sail that Cathy referred to was in the box. After reading the article on Lightning Strike, I concluded it read just like every other article Ive read on lightning protection for a boat. As I stated before: you are damned if you do and you are damned if you dont. quote from Sail mag "Could you have prevented a lightning strike? The answer is no; lightning is far too unpredictable and erratic in its behavior for anyone to prevent a strike. But could you have done anything to minimize the damage? The answer to that question is maybe." It goes on to say that is a REAL BIG MAYBE! I live in FL where you are more apt to be hit my lightning than to be attacked by a shark. We have been though some real bad thunder stroms before, my advice if you cant make it back to the dock is drop the sails, throw out the anchor, grab a beer, go below and say a little prayer!

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 07/24/2002 : 12:01:01

Does anyone know of a boat being struck by lightning? There must be 40 or so sailboats in my marina and you would think with that many metal masts pointing skywards, over the years, somebody should have been hit. In the marina where I winter store my boat there must be hundreds of masts and I have never heard of a strike there either. Is a lightning strike even worth fretting over?

Don Lucier, North Star
C25 SR/FK

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3324 Posts

Response Posted - 07/24/2002 : 12:38:55

In the last 5 years we have had 2 sailboats hit by lightning! A Ranger 23 which sustained innumerable small holes in the hull, and a Hunter 37 Legend (belonging to my ex-wife and her husband!) which had its electronics completely fried but no hull damage. Both boats were in their slips at the time. So, it does indeed happen...
Personally, if I'm sailing (or racing) and I see lightning, I get the hell off the lake - and if I happen to be PRO the abandonment flag goes up and the air horn starts its cadence!
Derek

Edited by - on

RichardG
Admiral

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USA
990 Posts

Response Posted - 07/24/2002 : 17:02:33

Derek:

"belonging to my ex-wife and her husband"

You didn't make a "deal" with someone, did you!?!

RichardG 81 C25 SR/FK "Sanity"

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3324 Posts

Response Posted - 07/24/2002 : 21:07:00

Richard - I'll never tell! :))
Derek

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/24/2002 : 22:28:08

Derek: I believe that most of the "fried electronics" cases are not from direct hits to the boat, but by hits to the water very close to the boat. The magnetic fields around the bolt are sometimes sufficient, and the discharge through the water to the metal components of the boat can do it, too. That could explain the lack of damage to the boat--such as holes in the hull or burned items inside.

Jellyfish: My logic is that lightning doesn't follow the shortest path--it follows the path of least electrical resistance. Wet air (with rain) conducts somewhat better than dry air, and metal conducts better than either, while fiberglass is a very good insulator, and dry wood is a moderate insulator. if the path through the mast leads to a fiberglass deck, below which is dry air, a wood compression post, and more fiberglass, the path of least resistance may turn out not to include the mast. It may be through the wet air 20 feet away from the boat. I was trying to rationalize how the smaller boat got hit next to the larger one, suspecting that it was due mostly to the larger boat having the mast base higher above and better insulated from the water. Maybe the Mac even has a steel compression post--I don't know.

Derek's story of "inumerable small holes" indicates that the path of least resistance turned out to be through the insulating fiberglass hull--and the only way through a true insulator is to vaporize it.

All of this is speculation--nobody can predict what's going to happen, and hardly anyone can explain exactly what did happen.

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette "Passage" in SW CT

Edited by - Dave Bristle on 07/24/2002 22:33:30

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mqp
1st Mate

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USA
46 Posts

Response Posted - 07/25/2002 : 10:13:49

I saw a boat's mast hit with lightning once (it was a friend's boat). The boat was not damaged except that the grounding wire that was attached to the keel bolt melted. There was hundreds of copper beads in the bilge.

--Minh

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Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 07/28/2002 : 13:41:52

This thread is always interesting. One prior post asked did anyone know someone who's boat had been hit by lightning. My wife Ruth and I have both had this up close and personal experiance. Let me say right of the bat that the Damned if you do Damned if you dont theory is right on track. Not even the pro's understand it yet and its all theory.
Ruth and I were struck by lightning while on vacation in Newport Beach California. We had gone to attend a launching party for a friends custom built 54' sailboat. My wife flew down several days ahead of me and unknown to me made some special plans. Rather than stay in an expensive local hotel she arrange fo us to stay aboard a beautiful old clasic Hershoff sailboat called Bounty. We were in the cockpit and enjoying the welcom basket of fine breads fruit and wine as we noticed the storm developing. It was quite a show to see lightning developing over the Irvine foothills and heading our way. We werent concerned as we had both grown up in the area and had never heard of any lightning damage from these rare storms. The storm rolled in closer. There was no rain, no ominous dark clouds just warm weather and white billowing clouds overhead. Several good bolts came down in the distance and the show was impresive untill it began to be to close. We were both talking about going below and began to notice static in out hair. How odd we thought and then the memory clicked in about the things we had read. The rigging began to make noise like a fizzing sound and I said we had better head below NOW. To late though and there was a huge flash and noise. The top of the mast had been hit and the lightning traveled down the 1/2" thick shrouds all around us and into the keel and water. It was very frightening and I never want to see it again. We were both very lucky to not have been hurt. One last bit of luck I had though was that this event was all caught on video.
Since this time I have had several more expriances with lightning. All have been work related and are all aircraft lightning strikes. I have done several survey and damage reports on commercial jetliners and have see some very strange things. My conclution to all this is that 1. there are many types of lightning and 2. Not one of the events has ever been the same. One aircraft had over 19 hole burnt in its skin, another had a ball of lightning travel down the isle and out through an overwing hatch with no damage. These state of the art aircraft has all the lightning protection in the world and were in flight at the time of the incidents. So I guess damned if you do and damned if you dont sums it up for me.
The damage that can occur from lightning varies from the extream to the un noticed but one thing is certain nobody knows where or when it will hit. Use good common cense be cautious and if you are caught out on the water take shelter as soon as you can.

Doug&Ruth
Wind Lass
Tacoma Wa.

Edited by - on

deastburn
Captain

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USA
334 Posts

Response Posted - 07/28/2002 : 22:45:22

Last summer I moored in Scituate Harbor, Mass as a storm came in. It hit just as we got to the Harbormaster's office and I stood in the doorway and watched a Catalina 34 at the dock get hit. The explosion was deafening. I learned later that the boat was "lightning protected" (which I took to mean grounded). The electrics and electronics were all fried, but there was no damage to the boat per se.

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