Association Forum - Lightning Protection

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

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.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Lightning Protection

New Topic

Topic Locked

Printer Friendly

Author

Topic

jduck00
Captain

Member Avatar

USA
313 Posts

Initially Posted - 08/02/2013 : 18:45:28

So.. I'm looking at installing lightning protection. I'm a sparky and have seen what a good bolt can do. I've got a swinger and I've though about bonding the mast base to the keel somehow.

I guess first question, is the top of the keel trunk above the water line? It looks close , but I can't really tell.

Second, has anyone ever done this?

In order to get any lightning system installed I have to get a path to water and really don't want to do it with a fitting below the water line.

Oh yeah, I finally quit lurking on the forums and signed up. You guys have been amazing so far. I hope to be in the water in 3 weeks. Lots of repairs and mods. Hope to post a decent amount of pics before I launch her.

Edited by - on

britinusa
Web Editor

Members Avatar

USA
5404 Posts

Response Posted - 08/02/2013 : 19:11:47

Welcome aboard Jeremy.
Nice Burgee

Paul

Edited by - on

John Russell
Master Marine Consultant

Members Avatar

USA
3444 Posts

Response Posted - 08/02/2013 : 19:56:23

There have been a number of discussions about this topic and I don't think there's really a consensus about its effectiveness.

Edited by - on

Voyager
Master Marine Consultant

Members Avatar

USA
5231 Posts

Response Posted - 08/02/2013 : 20:27:28

Sorry I can't comment on a swinger but you should have at least two options if you want to complete the electrical path from mast to water:
1. From the mast step tabernacle bolts connect a length of #4 AWG copper to the keel bolts (that's what I did on Passage),
2. Mount a 9"x9" grounding plate on the outside of the hull with a thru-hull bonding bolt in the bilge area. Run a #4AWG cable from the tabernacle to the bonding bolt.
Coat the connections with petroleum jelly to prevent corrosion. Make sure there are no sharp 90° or greater bends in the copper wire.

Edited by - Voyager on 08/02/2013 20:29:24

Dave5041
Former Mainsheet Editor

Members Avatar

USA
3754 Posts

Response Posted - 08/03/2013 : 04:20:14

An ongoing issue. It isn't conclusive, but data suggests that bonding increases the likelihood of taking a strike but offers some protection for the rest of the boat. The optimal solution appears to be an air gap bond - a cylindrical conductor around but not contacting the mast that is bonded to the underwater fitting. How tall it should be and how big of a gap is optimal is still a little vague. Hardly anything about lightning and protection is clear and absolute.

The swinger housing is below the waterline.

Edited by - Dave5041 on 08/03/2013 04:21:15

britinusa
Web Editor

Members Avatar

USA
5404 Posts

Response Posted - 08/03/2013 : 05:34:35

There's a pretty good document in the Owners Edu in the Members Area.

Paul.

Edited by - on

jduck00
Captain

Members Avatar

USA
313 Posts

Response Posted - 08/03/2013 : 06:06:25

I've actually been looking at lightning dissipation. I have a cousin that works for Lightning Masters and she gives it an honest thumbs up. It still has to have a path to the water. Which, if it doesn't work and takes a hit, that path needs to be robust enough for a lightning strike.

I'm leaning towards installing a grounding plate, but the whole thing may wait for the winter when I take back out of the water.

http://www.forespar.com/boat-lightning-strike.shtml

Edited by - on

Stinkpotter
Master Marine Consultant

Members Avatar

Djibouti
9013 Posts

Response Posted - 08/03/2013 : 08:54:43

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jduck00http://catalina-capri-25s.org/forum/googiespell/change_lang.gif
 ...I have a cousin that works for Lightning Masters and she gives it an honest thumbs up...<hr height="1" noshade id="quote"></blockquote id="quote">Surprise, surprise...

This is a hugely controversial subject, with "experts" on all sides, berating each other. You can find references to some of that by searching our own archives.

Where you sail, what are the actual experiences--out on the water and at the docks--protected and unprotected...? My assessment (purely personal, based on my circumstances) was that protection might attract a strike, and anything short of a solid copper mast that extends into the water is likely to be a path that a few hundred million volts will overwhelm--thus damaging the boat and possibly its occupants. Around here, it's not uncommon for lightning to hit the water close to sailboats with big metal masts, frying the electronics without damaging the boats themselves. But salt water might be different from fresh in that regard.

It's probably easier to avoid thunderstorms in my area than in Arkansas, but that was my primary strategy--I don't go out when they're expected, and I get the hell out of Dodge when they'e coming. (Now, weather radar on my iPhone is great!) At the dock, whatever happens, happens.

To use the swing keel, it seems to me you'd need to connect your cable to a stationary part, which would appear to be the hanger assembly, but that assumes some things about the electrical path at that point. (You don't want the hanger to become a hole in the boat.) The experts would probably tell you to forget that and install a copper plate on the hull. The conventional wisdom among protection advocates generally is "go big, or go home."

Edited by - Stinkpotter on 08/03/2013 08:57:13

pastmember
Master Marine Consultant

Members Avatar

2402 Posts

Response Posted - 08/04/2013 : 19:39:58

Talk people with taller masts in you marina into grounding their boat. It is amazing what people will fixate on. As a lake sailor I go in when it gets dangerous and remember that as a lake sailor you do not have to make it back to your slip, the shore is "just right over there". We have had several strikes to friends boats, one a Catalina 30 and the other a Hobie 18, no one was hurt in either strike; other than wallets. Regardless of anything you do, if your boat gets hit you are buying new instruments. A saying that has rung true so many times on this forum is "stop worrying about whatever you are fixated on and sail", (usually expressed to someone thinking of spending a lot of money to ad no value to their boat).

Edited by - on

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

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.