Lightning Proctection

[bmorton]

When I finally get my boat in the water I will be sailing in South Florida. Does anyone have some ideas about lightning protection? Big boats have systems installed that ground the mast, but what can one do with a CP16 to make it safe? Thanks -Brian

[kchunk]

Tough question and there is no right answer. Some big boats have systems to ground the mast...not all. Two schools of thought here: Provide a ground path for lightening; or try to dissipate electrical charges and insulate your boat from ground.

Personally, I'm of the school of thought that does NOT want lightening striking my boat. Personally, I think providing a ground path is inviting a strike...and I'm sure 50% of the people reading this will disagree.

My trade is aircraft maintenance for a major airline and I see the results of lightening strikes to aircraft all the time. Surely I realize a metal aircraft fuselage and a fiberglass boat fuselage are different with respect to how electricity will travel through and/or around them, but I bring that up to point out just how differently each lightening strike behaves as it move through a given material. Aircraft have provisions to mitigate static electricity and electrical discharges and in almost every circumstance, lightening does not behave like electricity is supposed to.

I was just reading a similar thread on trailersailor.com and read, what I feel, was an interesting way of dealing with potential lightening strikes. If lightening was threatening, this individual would deploy a conductor trailing the boat grounding the aft stay...sorta. The difference was that he would lightly insulate the point where he connected his ground conductor to his stay with electrical tape or similar. The idea is that he is not grounding the boat (making it more attractive to lightening) per se, however, if lightening does strike his boat, this light insulation between is boat and his grounding conductor will easily be broken down by the lightening, allowind the current a ground path rather than blow a hole in the fuselage. Interesting...but I don't know how practical.

Our boats are a bit different than most in that we don't have a metal keel in the water. IMO, if lightening were to strike my boat, what SHOULD happen is it will travel down the shrouds and when it has built up enough potential will jump the gap from the chainplate to the water and the (salt)water is the closest ground path, not a steel swing keel dangling from my hull (freshwater and saltwater and quite different insulating properties). I do know one thing, what WILL happen is probably quite different from what SHOULD happen.

Another way to avoid a strike is to moor next to a larger and/or more expensive boat. Both attract more lightening.

[Craig Weis]

Kchunk
Thanks I agree with you that 'to ground is to invite'.

A natural 'cone of protection' is created when lighting strikes the top-O-mast. A 60 deg. out and 360 deg around dispersal of the strike occurs.

I have seen boats parked on land with the stick up that have been struck by lighting. Blows a small hole in the bottom where the strike goes to ground.
Additionally about "2 Billion" pins holes, probably where ever glassfiber faces the outside of the boat, blows away the glass. Junk the boat.

Pay your money take your chances. What? With about 11 to 20 million lighting strikes a year in America...why won't the DNR let us have bon-fires?. skip.

[federalist]

Just finished reading the Handbook of Trailer Sailing by Robert F. Burgess (purchased directly from Hutchins Co.)  In the book it discusses grounding your boat in a storm to protect from a lightening strike (page 250).  The author suggests clamping one end of a jumper cable to the forestay and putting the other end in the water.

The book is a great read as it discusses the author's CP16 & CP 19 in detail.  If interested, get the first edition which was published in 1984.  Some info is "dated" but overall it is a great book for a Com-Pac sailor.

[mgoller]

Last weekend I was sailing for about an hour.  I thought I would put the spinnaker up and glide home on the good straight wind.  I did see the very dark cloud to my southwest but thought I could beat its arrival.  By the time I had the spinnaker up and ready I didn't check over my shoulder.  Just as I hoisted the wind kicked up.
It was a little more than a spinnker could handle but I thought once I was making hull speed the apparent wind would be handleable.
The spinnaker blew out and swung wildly in front of the bow.  I was surfing to home.
Then a squall from behind hit me.  It was so hard the simple loop knot started slipping at the clew.  The sheet pulled so hard it cut my hand.
That's when the first thunder sounded just aft about a 1/4 mile.
The rain started pelting me.  I decided to motor in with the spinnaker.  The 6 hp started right up, I revved it in forward to all out.
The spinnaker couldn't be handled so I let it just do what it wanted while I motored in.  By now the air was white and the wind was 50 mph gusts.  That's when the next lightning strike was just behind maybe 200 yards.
I knew I was the tallest thing in the middle of the lake so I made sure to not touch metal.
I had two choices, go below and just drift in a squall or keep motoring home with no sails.

(I went to the Boston Museum of Science years ago where they have a really good lightning exhibit.  They make lightning with a machine.  One of the things they do is hoist a man in a metal cage and strike the cage with lightning.  The man is unharmed because of the nature of electricity flowing around the outside of a hollow metal object.)

My ComPac 19 is a lot like a hollow metal object.  It is a metal tent, with a pole, fore and aft and side to side metal cables.  These all lead to reinforced fiberglass.
If my boat was struck that day I would have been safe.  In fact the static charged atmosphere may have looked at my boat and declined in favor of a large tree on the beach which was nicely grounded.
Had I grounded my rig to the water I may have been hit, but still safe nside my metal tent.  Personally I'd rather not hear the thunder clap of a direct strike regardless.

My neighbor came out to save me as I coasted in fast and beached in the shore's mud.
I put the hatch in and jumped off.  By now it was howling a squall and blasting us with icy hail.
30 minutes later the sun was out and hot.

[Potcake boy]

MGOLLER,
I'm not a scientist and don't have all the answers to the lightening mystery, but from what I've read a modest ground on your vessel is not an adequate path for the energy in a lightening bolt.  The purpose of a ground is to prevent a strike by neutralizing the electrical potential of your vessel thereby not providing an attraction for the strike. Try Googling "cone of protection" for more from the experts.

Did your spinnaker survive?

We can only pray the winds carry us home.
Ron

[Craig Weis]

Not that I would ever do this, but many saw pictures and the post about a "KEELBOOT" that is on the bottom of my C-P 19's keel used to run over rocks. Armor plate if you will . Save the glass.

This simply is a flat 6 mm 5383 [or 5083] marine aluminum plate saw-cut to the shape of the keel and glued on with Marine-Tex and faired in with a bit of grinding. Adds about 15 lb at the bottom of the boat. OHHhhhhh yea!

Note: Every 1 lb at the top-O-mast requires about 15 lb at the keel on C-P19's with a 25 foot high mast above the water.

One could run an '0' size coper wire used as welder lead, [having several hunderd strands of fine wire] clamped from the stern turn buckle of the standing rigging, over the transom, glued and faired down the back-bone line of the hull and lugged on to this KEELBOOT plate via a small welded fitting.

That effectively provides about 950 sq inches or 6-1/2 sq foot of grounding area.

I'll just let the lighting blow a hole in the bottom of the hull and swim home if I can.
Why welder lead? More surface area, it has less resistance, flows electrons better. [see 'Off Topic"]

" I'm not a scientist, but I stayed at a Holiday Inn Express..." Snicker, snicker...skip.