{"id":1173,"date":"1999-11-30T00:00:00","date_gmt":"1999-11-30T05:00:00","guid":{"rendered":"https:\/\/setsail.com\/?p=1173"},"modified":"2015-10-16T12:05:43","modified_gmt":"2015-10-16T17:05:43","slug":"lightning-protection-system","status":"publish","type":"post","link":"https:\/\/setsail.com\/lightning-protection-system\/","title":{"rendered":"Lightning Protection System"},"content":{"rendered":"
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Hi Steve, Once again here I am at your information trough. Well, INTERLUDE is on the dry getting bottom job so I am going to address the long-overdue absence of some form of lightning protection. Here on the Mississippi Gulf coast, lightning damage is a very real threat, as my dock neighbor got a firsthand appreciation of the awesome damage a strike can inflict–all electronics shot, and a total of 72 exit points in the hull, 4 of which where about 1\/4″ in diameter–2 below the waterline. Flooding was kept in check because the 2 major exit points occurred in integrated water tanks<\/p>\n

INTERLUDE, a Hans Christian, Christina 40, has a deck stepped rig with all metal components except chainplates bonded together with #8 cable. Why they omitted the chain plates is beyond me, but I intend to address that in this project. <\/p>\n

What I am proposing to do is construct a submersed ground plate, 5″ by 72″ of 3\/16 or 1\/4″ copper, connected thru the hull with silicon bronze 1\/4″ or 5\/16″ carriage bolt connectors and marine sealant every 8″ or so (overkill?). This satisfies the ISO ground plate standard of 2.5 sq. feet. The reasoning behind the plate dimension is that studies have shown that the edge surface of the conductor plays a very important part in strike dissipation. So, in an attempt to improve on the ISO standard, I have increased the exposed linear edge rather than just going with a square plate. To this plate via the carriage bolts, I will connect #4 cable to the compression post and #6 to the chain plates. <\/p>\n

Now comes the problem of the mast to compression post connector. The aluminum mast sits on a stainless deck base which is through-bolted to the bronze compression post. Intuition tells me not to rely on this mechanical connection but weld a lug to the mast and again connect one of the stainless through-bolts to the mast with #4 cable which should insure a good low-resistance electrical path. At the masthead will be a rod sticking 6″ above the VHF antenna and for good measure, one of those bottle-brush dissipaters. OK, now I have that immersed chunk of copper. Will I be inviting cathodic problems if I include these components in the bonding system or should I isolate the lightning protection components (mast, stays, chainplates, compression post and ground plate) from the bonding system and let them reach their own electrical potential? What do you think of the solution? Thanks, so much. All the best to you, Linda and the family, Kevin, Bay St. Louis, MS.<\/p>\n<\/div>\n

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Hi Kevin: Lightning is a tough question and I am not sure there are any pat answers. Sounds like you have taken the right approach. A couple of comments:<\/p>\n

1-You might want to consider one of the sintered metal grounding plates. These are filled with holes and apparently have a substantial effective surface area, without being too large overall. We’ve used these for years under the mast steps on our fiberglass boats.<\/p>\n

2-Lightning does not like corners, or resistance joints. It would probably be safest to have a hard connection from the mast to the grounding plate which should be mounted directly below the mast.<\/p>\n

3-All of the metal aboard–chainplates, lifeline system, deck hardware, steering system, should be tied to the lightning bonding system. What you do not want to have is different electrical potential between metal because your body can then become a conduit to equalize the difference!<\/p>\n

4-Our own feeling is that the ion bleeder system, i.e. the brush on top of the mast, is the most important part of the equation. This helps to prevent the strike in the first place by bleeding off the ion charge before it can create a “leader” to the the cloud which is thought to make a path for the high-energy strike.<\/p>\n

Good Luck–Steve <\/p>\n

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Hi Steve, Once again here I am at your information trough. Well, INTERLUDE is on the dry getting bottom job …Read More<\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10,21],"tags":[],"class_list":["post-1173","post","type-post","status-publish","format-standard","hentry","category-tech-talk","category-yacht-systems-faqs"],"_links":{"self":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/1173"}],"collection":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/comments?post=1173"}],"version-history":[{"count":1,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/1173\/revisions"}],"predecessor-version":[{"id":35992,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/1173\/revisions\/35992"}],"wp:attachment":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/media?parent=1173"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/categories?post=1173"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/tags?post=1173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}