Grounding for lightning, and for electrical system

[Jason]

Hi Everyone,

Hope you're enjoying winter.  I am not advanced when it comes to electrical circuits.  I wired up a simple system in my CP16 that I'm happy with, but I have some questions on grounding that I would look forward to an opinion on.   Do we need to worry about grounding for lightning in a storm?  I've read that some sailors will connect a battery cable to a mast stay, and let the other end drag in the water.....  Also, the electrical system I installed just has all the grounds leading back the negative terminal on the battery; should the onboard electrical system be somehow further grounded?   These questions may make my lack of understanding on this topic pretty obvious, but thanks for any input. 

Thanks!  -Jason

[skip1930]

Jason commits, " Do we need to worry about grounding for lightning in a storm? "
Well I have thought about this for a long time. Done nothing, but thought about it.

JBC says; "...thunderstorms were buzzing the rigging." <--Saint Elmo's Fire, as reported by clipper ships rounding the Cape.

A lightning strike assumed to strike at the top`O-mast will splay out like an opened umbrella. And then travel down the mast looking for a good ground...that be the water under and around the hull. If the strike does not force the mast clean through the cabin and out the bottom of the hull, the energy will pin hole the fiberglass with a bizzillion little leaks and she'll be no more. Our friend had his 36 foot sail boat struck by lightning while on the hard. His hull was like, well...soft fibers that one could punch a fist clean through. It's like all the epoxy resign is blown away leaving only the fibers of glass. He gave the boat away for parts.

Guys toss battery jumper cables over the side that are attached to the standing rigging. In my opinion that's like peeing in the ocean to make it overflow. Ain't gonna happen.

I thought about bolting on with a bronze lug, a '0' size~20 strand cable to the back stay of my CP-19, down the transom and following the aft curve of the keel and attaching the cable with a lug to my KEEL BOOT, a 6mm aluminum flat plate glued to the bottom of my flat fiberglass keel. Should go to ground that way...but a direct strike...I'm thinking it is curtains for the boat and maybe me.

skip.

[JBC]

I don't have any expertise either about lightning solutions, so won't venture an opinion.  However, I will relay that one time when out on the water, a long time ago in an old Sea Crown 18, thunderstorms were buzzing the rigging.  Really.  We were heading in to get off the water when I happened to touch the boom and ZAP, just knocked my hand away like I had stuck a finger in a wall socket or something.  Pretty surprising.  Got the boat into shore and off of it with no other mishaps, but spoke to another trailer sailor whose boat had been hit by lightning the week before.  He thought it had made it just fine, until he put it in the water only to discover what Skip described, bunches of little pin holes in the fiberglass that leaked and started sinking the boat.  He got it back onto the trailer ok, but the boat was history.

[MacGyver]

In the 16 years I have worked at the marina, I have seen a few boats get hit by lightning, well one for sure that we had to rush to save.
A CandC 35 got hit right at top of the mast. It was grounded to the keel in the fact that it was sitting on the keel step then 2 ground cables to the keel.
The lightning blew all the thru hulls out of the boat, craze cracked the rudder as the lightning either found its way into the rudder to the skeleton, or something..... Keel had some pock marks all over it. and the hull had stripes all through it....

Pretty cool....... but we had to rush with the pumps as we watched the storm move away not thinking about ourselves just to save the boat.
GET IT TO THE LIFT a guy shouted as we ran a large gas pump with 3 inch line sucking the water out as we tied up to it hauling it over to the lift.

The other was a Catalina 36
Hit while out on the lake. Blew all the electronics out of it. Mast is on deck unlike that CandC.   NICE rich persons boat, with lots of gear.....every piece was shot.
hull in good shape, nothing else was a issue as far as hull and such.
And to mention, neither boat had any marks on the masts........

Lastly, I got nailed myself inside of a building........ with around 150 to 200 masts close by, the lightning struck the ground across the road, and at that moment I was unluckily leaning against the fridge......
I was soaking wet which they say (other survivors and doctors alike) is what saved me.
I spent the last few years fighting to get better, with the list of issues still about a page long. that list is shorter though........ a lot shorter.....

The only thing I can tell you is, from what I can tell, if you hear it, fear it, if you see it, flee it.

It is best to take care of yourself, and spare yourself from the pains and such that come with getting hit.
As for the boat.....well.......... that is what insurance is for....

IF you stay on the boat during a storm......   My wife, and I were on our 19 during a storm last year..... she was scared... me not so much.... the thing is, if it is gonna nail something, it is going to do it....... just hope and pray for the best.

Nothing really gives you or the boat better chances, they just hope it does.

Mac

[MacGyver]

OH! both of those boats are still used today, and docked at our marina.

The CandC was totalled out. guy bought it back and had us fix it.
the Catalina was repaired by a big company specializing in the electronics he had.

Mac

[Bob23]

    In this book, there is great information on grounding, bonding plates and lightening protection. It's also a very throrough and practical book on electrical systems used on sailboats. I found it very helpful when rewiring my 1985 23/2. It may be a bit overkill for your 16 but for 15 clams, it's a good investment.
http://www.amazon.com/Sailboat-Electrics-Simplified-Don-Casey/dp/0070366497/ref=sr_1_1?s=books&ie=UTF8&qid=1359367945&sr=1-1&keywords=sailboat+electrics+simplified
    My father in law used to keep jumper cables on board his Irwin 21 in case he got caught in a storm. Never had to use 'em so we'll never know if it works. Based on info in the book, I think it's a futile attempt at lightening protection. But it may be better than nothing at all!
Bob23

[millsy]

I do many lightning claims- most are limited to damage to sensitive electronic equipment.  Occasionally there is physical damage or signs ranging from soot marks at the masthead to blown out chainplates or thru hull fittings, holes along the waterline, etc.  The path frequently is through the shore power connection.  Every strike has to be taken individually and systematically investigated, but again most are minor and happen when nobody is onboard.  This is in no way intended to minimize the risks or dangers to persons onboard a boat when struck however.

There are many different ideas out there with respect to what constitutes a "proper" lightning protection system.  NFPA has a standard, yet some years ago the ABYC went from a  LP standard to "technical advisory bulletins".  It has been my experience that a traditional system that connects all of the rigging and other metals to a ground plate results- more often than not- in less damage to electrical equipment, and more importantly less damage to the crew. 

That said I do not have an LP system on my 23, using the logic that we are not living aboard or cruising and are therefore less likely to be onboard when a strike occurs (in the summertime though, when a strong storm rolls through while we are out at shell island I remind everyone not to hold on to any rigging!).  The same logic can be applied to not standing under a tree or remaining on a golf course during a storm I suppose.  We were hit by lightning many years ago when living onboard our big boat (with a complete LP system), and I took to reworking the instrumentation so that I could remove it and store it in the microwave oven (sort of a faraday cage) when it wasn't being used.  I haven't figured out how to do that with the circuit boards in my torqueedo!

[NateD]

You shouldn't do anything else with your electronics, the grounds should go back to a grounding bus or the negative terminal on the battery. There isn't much you can do to protect your electronics if lightning hits, dragging jumper cables or other grounding techniques are meant to protect the boat/rig/crew.

After a lot of research on the topic I gave up on adding any kind of protection for my boat. Many boats are hit each year, some of them suffer minor damage, fewer suffer critical damage (not always below the waterline), and only rarely are crew seriously injured. If a storm starts up, unplug any electronics you can (though that isn't a guarantee they will survive), and try to keep away from the rig/metal on the boat. It's unclear if even the most complicated and expensive systems offer much protection.

I haven't intentionally gone out in thunderstorms, but they have popped up while sailing/at anchor. They make me a little nervous, but the chance of fatal injury is pretty low. Us humans (and particularly sailors) generally have overactive imaginations when it comes to danger, what we tend to overlook is the mundane and common. Take a look at the US Coast Guards accident/death statistics (2011: http://www.uscgboating.org/assets/1/workflow_staging/Publications/557.PDF)

In 2011 there was a reported 533 boat related drownings, 415 of those souls were not wearing life jackets. If you want to boat, and want to live, wear a life jacket and require crew to wear one too. Everything else is pretty low probability.

[MacGyver]

I agree with NateD but offer this as far as storms, like I said before, If you hear it, fear it, if you see it, flee it.

Sure the chances of lightning getting you is low, but I can tell you first hand that it getting you is not a good idea.

we find in the lightning survivors group that too often they consider one not die-ing from it to be a good thing......... they dont tell you all the consequences of having it course through your body.   Too often it takes a few days for symptoms to show up totally, and a few years to fully develop.

My point is, avoid the storms, be cautious. 

And my opinion on safe gaurding the boat is that if it is going to happen, it will happen, and frankly it is doubtful much will help the situation.....

As a side note, do you see anyone putting lightning things on their homes anymore?   Used to see those things all over..........

Mac 

[wes]

I have never been on or near a boat when struck by lightning, nor has my boat ever been struck. But a few months ago a tall tree in my backyard took a direct hit, and the collateral damage was amazing. Everything electrical within a hundred yards was pretty much destroyed, despite having no connection or even close proximity to the tree. I'm talking about pool pumps, the house's alarm system, all the outdoor GFCI receptacles, etc. Lightning packs an astonishing punch, as I'm sure Mac will attest.

If my little 19' sailboat were struck, there's no doubt in my mind that no preparation on earth could save the electrical and electronic equipment. I'd bet good money that even the battery powered hand held VHF would be toasted. I think the only serious debate and discussion should be about how to keep the physical damage to the boat minimized so she doesn't sink. And I'm not sure there's even a good solution to that except prayer, and keeping one's insurance premiums paid up.

Wes