Lightning Damage

[rbishop]

This year I have experienced a considerable damage to my ship electronics due to lightning strikes. Does anyone know of a manufacturer of marine lightning protection gear that can protect my GPS and autopilot systems?

R. Bishop

 

[oldsaltoz]

G'Day rbishop,
Welcome to the YBW.com forums, I see this your first post, not counting the same item in the power boat forum, (You will get burned doing that).

Anyway, you can have a look at the site below, I'm not sure it's even possible to protect electronics at sea, but reading the information will give you an insight.

I Hope this helps.

<A target="_blank" HREF=http://www.thomson.ece.ufl.edu/lightning/SGEB17.html>http://www.thomson.ece.ufl.edu/lightning/SGEB17.html</A>

Old Salt Oz....../forums/images/icons/cool.gif

 

[Guest]

The site is very interesting.....but I think it oversimplifies the issue, and is in conflict with other information that states that anyone on a boat within the cone of protection is safe.......

But without excess dialogue.....I live in a marina in Southwest Florida, and interestingly enough all of the boats that have been struck by lightning have had these witchcraft type of lightening dispersers or ion dissipators or whatever.

I think if you are signifincantly worried about a lightning strike you should find a way to create a Farraday cage on your boat, or drop a large size copper plate over the side connected to a wide copper strip that is connected to your rigging. Whatever you do.....don't bond your boat and especially the thru-hulls to the lightning protection, because if you do and you are hit, there is a high possibility that your thru-hulls will vaporize and your boat will sink. Also, do not use a sintered bronze plate for a lightning ground. It is the kind used for an SSB ground, as it will literally explode if you are hit and you may have damage occur due to the explosive vaporization of the plate. Use a solid bronze ground plate.

Reality is the cause of all stress!!

 

[Chris_Stannard]

Advice from electrical wizard at Najad was to have a pair of heavy duty jump leads on board and hang one on each side from the shrouds. He said this is the standard answer in Sweden where lighting storms are frequent in the summer. I do not know how effective it is, but if anyone from Sweden reads this they might like to comment

Chris Stannard

 

[bedouin]

There is no sure fire way of doing this.

Most so called protection devices are designed to protect the structure of the boat from damage rather than the electronics. Even if you have chains or jump leads attached to your shrouds then a lightning strike will still take out your electronics - though the chains may stop it sinking the boat as well.

What is worse, lightning doesn't have to strike the boat to fry your electronics.

 

[chas]

That is interesting. If you were at anchor and put a jump lead between the forestay and the anchor cable, would that give any protection?

 

[peterk]

Re: via anchor cable?

chris ,
lightning is known to be capricious.
If it were logical it would
always
take the shortest route .

In a wet lightning storm this
would be down the shrouds
into the water

...peter, www.juprowa.com/kittel

 

[Danthegorrila]

The thing I have heard but never had to try is to be able to remove gps radios etc and put them in the oven.

It makes a improvised Farraday Cage.

PB

 

[kgi]

I believe Nigel Calder recommends you put items in the oven, in the military they call it hardening, ie, you are protecting it from an electromagnetic pulse (emp) basically you leave no pathway for the magnetic charge to follow and it is dissipated on the cookers casing, i do it purely because it makes sense, and i put the h/h vhf, h/h gps and the hand bearing compass in there, i have experienced a very close lightning strike (within fifty feet) and it knocked the radar, vhf , and the depthsounder out, radar came back after it was reset a couple of times, depthsounder after about four hours, but the vhf and the aerial were history, funny thing is i could still recieve, but there was no transmit........keith

 

[Guest]

Frying equipment is, of course, a problem. More importantly, what happens to those on board - are they fried too?

Ray

Ray

 

[oldharry]

There have been a number of interesting debates on these boards over the years about lighning strike protection, and the only clear thing that has emerged is that there is no known way of avoiding it. Personally i favour the idea of earthing the forestay (or backstay) well into the sea, on the basis that lightning MAY follow the shortest easiest route to earth.

But this does not explain lightning damage to moored or anchored boats....

Completely disconnecting all electrical gear helps avoid it being incinerated.

Crew members have been advised to wear rubber boots and gloves, and to avoid touching any metal objects during a lightning storm. A nearby strike can induce sufficient current in metal fittings to give a nasty shock. One correspondent suggested male crew should wear condoms for added protection of extremities.....

Do NOT connect lightning plates through the hull. Many boats have been sunk by these plates, or metal skin fittings being blasted out. Through hull transducers are particularly vulnerable to being vapourised.

A variety of devices intended to give lightning protection are available on the market, some at considerable cost. The general feeling is that the only protection they offer is to the makers Bank account: independent testing in the US some years ago on a range of products found they offered no apparent reduction in the rate of hits, and in some cases appeared to actually attract them - although this could have been statistical anomaly. Always remember that a Lightning Conductor as attached to tall buildings is just that - a conductor in the form of a heavy copper ribbon with a spike which is intended to ATTRACT the main charge and take it safely to earth without damaging the building.

Avoid having anything with a sharp point at the masthead. As the pre-strike leader descends, corresponding streamers rise from any sharp points on the ground, trying to connect to the descending leader. Once one makes contact, the main discharge takes place. By avoiding having anything at the masthead which helps form the upward streamer, you can reduce the chance of being struck by a measurable degree. (Note I have simplified this description for clarities sake). The idea of the 'witches broom' type of protection is to dissipate the upward streamers. The theory sounds OK.....

But I will continue to hang an earthing link over the side when caught in an electrical storm, on the basis that DOING something makes me feel a bit better about it....

 

[kgi]

No, just scared S***less!!!!!!!!!!!!!

 

[Spacewaist]

Interesting. Exactly the same thing happended to me off Lisbon. All instruments came back other than the (Swiftech) VHF which woudl receive and not transmit.

 

[rbishop]

I assumed that to be a very big possiblity. I did install a coast guard compliant primary grounding system on my 28' sailboat. I believe this saved our lives on one occasion, as well as the boat itself.

 

[Guest]

Lightning dissipators ...

The amount of charge / shock given in that split second by a lightning strike is unlikely to be disspiated sufficiently by any add-on ......

I have been on a commercial ship hit .... fried all radio gear in Radio shack .... neat hole blown in the VHF antennae and then fed down through mast etc.

I have been sitting in a previous office when it hit the Braodcast antennae on the roof ..... fried all the PCS on the network as it entered the network cables etc.

Both had dissipators .... the building had an enormous one .... made no difference .....

 

[rbishop]

Yeah.., I was glad I had an extra clean pair of underwear on board as well!

 

[vyv_cox]

With a deck-stepped mast I think there is just as much justification in not earthing the rig to the water. Why attract lightning unnecessarily?

However, the one thought that over-rides all others in a thunder storm, is "why would a spark several kilometres in length be deflected in the slightest by a piece of chain or wire a couple of metres long?"

To contribute to the discussion on the level of charge surrounding a lightning strike, I was sailing a Hobie 16 on Bala Lake when a thunderstorm arrived very suddenly. We sailed to the beach, disembarked and I was hauling the boat towards the shore, standing in ankle deep water, when lightning struck a nearby hill, probably at least 1 km away. I received a noticeable "belt" down my arms, touching a bridle wire each at the time. I quickly let go and allowed the boat to fend for itself!

 

[rbishop]

Thanks for the reply.
I do have a coast guard compliant primary grounding system on my boat. I believe that this system has save lives on one occassion and the boat on at least two. I also believe you are correct about the induced currents. I think this has contributed much to my electronics being destroyed which is very irritating and costly. Sure wish there was more out there to protect equipment than the stupid "fuzzy brush" and a primary grounding system!

 

[rbishop]

Re: Lightning dissipators ...

Thanks for the reply.
Yeah the damage is great.
However, I have a friend who installs and services cell and PCS radios for the large carriers. He says they insist on have lightning protection device installed to protect their gear. He says they work great. I was hoping someone might of of a company who has similar device for marine applications. It stinks to have to replace this gear.

 

[rbishop]

Wow! that's an interesting experience to say the least. Good thing it did not strike any closer than it did!