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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Is this lightening protection?

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Rainwater
Deckhand

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22 Posts

Initially Posted - 04/15/2014 : 17:38:13

I recently bought a '74 Catalina 25. The previous owner told me the plate on the port side was an old patch that someone (not him) had put in to stop the thru hull on that side from leaking. Upon further examination tonight to see what it was going to take to get the head working, I noticed a heavy gauge wire leading from what looked like a grounding lug up to the mast step. I have the boat pretty well covered in heavy tarps but It went right up through the ceiling where the mast sits. Anyhow, when I was looking at the thru hull I noticed that it wasnt capped off. I went outside and looked at the "patch" it wasnt even really near the thru hull, in fact it was right where the ground lug I saw inside was. Is this normal to have this on this boat? Should I just eventually remove it? From the outside it looks like a plate thats about 6 inches wide and a foot long with what looks like a carraige bolt through it in the middle.

"Lisa Rene"-1978 C25

Edited by - on

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 04/15/2014 : 18:08:47

If it was built in 1974, I don't think it's a Catalina 25. They weren't built in 1974. It might be a Coronado 25, which was also a Frank Butler design, and was in production until about 1975.

From your description, it sounds like a lightning grounding plate. There are differing opinions as to how much protection it offers - not much if it isn't done well. If it's going to be done, everything above decks should be grounded, not just the mast. (including all lifeline stanchions, chainplates, etc.) Some people contend that grounding the boat actually attracts more frequent strikes, but reduces the severity of damage. Some people ground their boats - most don't. It's your roll of the dice.

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Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 04/15/2014 : 20:51:25

No manufacturer I know of puts lightning protection systems in their boats--the liability would be too great when it "fails." What you have sounds like somebody's attempt. IMHO, and with all due respect, nobody here (or just about any other mortal soul) is qualified to advise you on it. I've read opinions across the spectrum, including from academic "experts", and I've concluded there are many ways to do it wrong and probably no ways to do it "right." Google it, and prepare to be befuddled.

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Voyager
Master Marine Consultant

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USA
5231 Posts

Response Posted - 04/17/2014 : 19:16:59

Not to add fuel to the fire, if you have a hull grounding plate, either go full in and research the theories, or disconnect it completely and turn it into a "hull ornament"!

Edited by - Voyager on 04/17/2014 19:22:30

JohnP
Master Marine Consultant

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1519 Posts

Response Posted - 04/18/2014 : 09:57:01

Dave is right about the lack of solid information about lightning protection for sailboats. After I bought my boat I read lots of that confusing info. Some experts think there is less risk of a strike on salt water since lightning frequently connects to the better-conducting surface of salt water than the surface of fresh water. We all know that lightning does hit tall trees and tall buildings, so being the tallest electrical conductor out on fresh water has to increase your risk somewhat from a passing thunderstorm.

Where the experts differ is how to minimize the damage to a boat caused by a million volt pulse! You could imagine that if they tested various grounding setups on various boats, those would be ridiculously expensive experiments!

I concluded the best way to avoid damage from a lightning strike on my boat is to quickly head for shore and go home!

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pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 04/18/2014 : 17:42:11

The best defense is having the shortest mast on the dock. Mine is the shortest by a lot.

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Rainwater
Deckhand

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22 Posts

Response Posted - 04/18/2014 : 19:21:17

Thanks Everyone, I am going to remove it. I use to work for a radio company that installed and maintained radio equipment on the large towers you see along the road. They even sent us to a "grounding" school by motorolla, but even though everything on a couple of towers was properly grounded, sometimes it would still get eat up by lightning when it got struck, sometimes it wouldnt. I think its a crap shoot personally. I just dont want it on there, I would like to take the plate off the bottom of the hull but maybe I'll do that next year, I'll have a hole to patch from what I can tell.

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GaryB
Master Marine Consultant

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USA
4275 Posts

Response Posted - 04/19/2014 : 08:15:48

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by pastmember
 The best defense is having the shortest mast on the dock. Mine is the shortest by a lot.
<hr height="1" noshade id="quote"></blockquote id="quote">
While having a shorter mast might help a little, it's really about where the charge reaches the point where it will cause a lightning bolt to develop. If your boat is at that point it will get hit even if a boat next to it has a taller mast.

I once saw a news report where someone was hit by lightning in the middle of the lower section of a major league baseball stadium surrounded by thousands of other fans.

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Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 04/19/2014 : 12:16:46

Another variable Is the mounting of the mast. The C-25's is stepped on the cabintop, with over 5' of air space and several layers of fiberglass between it and the water. The stainless shrouds are relatively poor conductors. Some other boats have the mast stepped on the keel, or a steel compression post between it and the keel.

But in the end, lightning will do what it pleases. I agree with the strategy to not be out in it, realizing that's easier to implement in CT than in FL.

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.