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Popeye
15th August 2011, 05:49 AM
A fibreglass boat and a ligtning strike i a mixture for disaster and a sailor who ignores it or believe that he or she will never be struck by a lightning bolt is a fool!

There are many ways and means tried and tested those that worked we know about those that did'nt we haven't heard about and my idea is not fool proof but i am pretty sure i will work and i am open to correction.

I have decide that i will rig my boat as follows:

Fit a solid copper rod to the mast extending .5 meter above the mast runnining though the bulkhead till under the saloon floor where it will split in two, fololwing the contours all the way down to the mini keels where its attached to a copper plate that is attached to the keels. Between the copper plate and the glassfibre keel is a thick rubber to avoid a flash back of the elctrical bolt. On deck run a copper band to either side where any high point stainless Steel may be.

Isolate the engines with its owns startup batery and run earth wires to the the dissapating cable.

While this is not fool proof it's better than doing nothing at all! It has been calculated that one single lightning bolt can keep New York's lights going for 7 days! This is serious stuff one cannot just sit back and do nothing!

James Val Jackson
15th August 2011, 07:28 AM
A fibreglass boat and a ligtning strike i a mixture for disaster and a sailor who ignores it or believe that he or she will never be struck by a lightning bolt is a fool!

There are many ways and means tried and tested those that worked we know about those that did'nt we haven't heard about and my idea is not fool proof but i am pretty sure i will work and i am open to correction.

I have decide that i will rig my boat as follows:

Fit a solid copper rod to the mast extending .5 meter above the mast runnining though the bulkhead till under the saloon floor where it will split in two, fololwing the contours all the way down to the mini keels where its attached to a copper plate that is attached to the keels. Between the copper plate and the glassfibre keel is a thick rubber to avoid a flash back of the elctrical bolt. On deck run a copper band to either side where any high point stainless Steel may be.

Isolate the engines with its owns startup batery and run earth wires to the the dissapating cable.

While this is not fool proof it's better than doing nothing at all! It has been calculated that one single lightning bolt can keep New York's lights going for 7 days! This is serious stuff one cannot just sit back and do nothing!

O.K. & g'day 'Popi' :p With great respect - that is :) I'm sure with you on this subject. It's a great-big bother to me also. :eek: Can't justify $50K in any bodies money to over/falsely insure my yacht. :o Prevention is 1000% above any possible cure, for sure. :cool: We all need IMHO much greater detail as I'm following your recommendations :D So my young (at heart :p ) fellow, cough-up with every little detail - if not in here then e-mail me direct. Please. I'm at jamesaviculture@hotmail.com Now as to priorities - which first - Lightening protection or Sea-brake????????????? :o I live & sail in & around - Far North Queensland & SE Asia (Cairns, Darwin, Phuket, Langkawi, etc & the usual # of lightening strikes - during the tropical cyclone/wet season is easily 500 to a 1000 per week & sometimes up to 300 a day. VERY dangerous :( My tri & cat are fiberglas foam/cedar sandwich & a 'strike' would destroy the whole of either boat - I'm sure. :( I've spent 40 yrs building fiberglas yachts so I do know the material well. All of that knowledge makes me even more cautious. Any & all information will be treasured. :) :D Thanks & Ciao, james Keep well, great sailing & Thank you. jj

Popeye
15th August 2011, 08:40 AM
Hi James and thanks for your reply. I seem to think the lightning prevention enjoy a much higer priority as Catbrake as current methods can still be employed untill such time that one decide to install a Catbrake.

I am awaiting a final report from a tecnition form our electricity supply commission for some specifications on the main rod that run alongside the mast as you can immagine parameters like weight and adequate rod size that can absorb a strike are relevant ignoring this might be waste of time overall.

I will email you direct before Friday this week with more specific details which i will then add to the forum for whoever can use it or some of it.:)

ColdFusion
15th August 2011, 11:10 AM
Regarding installing a copper rod lightning conductor alongside your mast, I really can't see any (perceived) benefit of this when the vast majority of catamaran masts are already electrically conductive, but if you happen to have a wooden mast, then fair enough!

I've read lots of conflicting advice over the years about lightning protection for yachts. I also have a vague recollection of reading that one yacht was hit while another adjacent yacht with a taller mast was not, and that neither yacht had any form of lightning protection installed. Both were monohulls in a marina, if memory serves me correctly.

One school of thought seems to be that taking measures to increase the grounding effectiveness of a yacht actually increases the likelihood of the yacht being struck as 'leaders' are sent up to attract a bolt of lightning. On the other hand some people think that if a boat is struck then any grounding measures taken will dissipate the electrical energy more effectively. To my little brain it all seems pretty random and therefore almost impossible to predict (until we know more). Lots of people have theories but nothing, as far as I'm aware, is proven. I'm open to being persuaded otherwise.

kim s
15th August 2011, 12:42 PM
Just to put my 10 cents worth in (for the non uk members ) or 2 bobs worth,

as far as I was aware, there is NO full proof wayof protecting a boat from a strike.

thats becouse weknow What it is but do NOT know how, why or what triggers it.

I seen boats almost disintergtrate after a strike. and others with superficial damage. both wooden masts, no lightning rod.it does depend where the strike jumps too.

the only safe way is to have a metal boat. stillgetstruck but being a faraday cage there is noproblems.

I have actually sailed through the steam of where a strike has hit the water maybe 5 metres in front of us. we had ally mast, earthed rigging too plates , serious yacht (been round the world twice) why did it not hit us???

there are lots of theorys. why muck about going through a metel oxidised mast when it can go to the perfect ground.
aargh ------but lightning flows upwards, ok so why does it trees and go DOWN to the ground---

like I said ---no one really knows.

I have sailed in lots of thunder storms and not been hit.
my mate has been hit twice. (i dont go sailing with him:eek::eek:)

I think its one of those things that you do what you feel is best. wether it actually does any good---who knows. difficult to prove. and a good placibo effect

the only think I do is put a spare hand held vhf, gps, and mobile phone in the oven. put up an umbrella-------(joke) and wach the show

Kim

ColdFusion
15th August 2011, 12:52 PM
the only think I do is put a spare hand held vhf, gps, and mobile phone in the oven.

Do you pre-heat or just whack 'em in for half an hour at gas mark 5? ;) :D

















OK, I'll get my coat :o :rolleyes: :D

kim s
15th August 2011, 07:14 PM
Do you pre-heat or just whack 'em in for half an hour at gas mark 5? ;) :D

::)::)

would that be a duffel coat or an Macintosh:D:D

Kim

ColdFusion
15th August 2011, 07:28 PM
would that be a duffel coat or an Macintosh:D:D

Straitjacket

BigCat
24th August 2011, 08:14 AM
Lightning likes to go straight down. This is a point in favor of biplane rigs, because you can put the grounding plate straight under the mast. Lightning doesn't like to turn corners, so keep everything as straight and vertical as possible. Saw a study in professional boatbuilder magazine about this a couple of years ago, I think it was.

Popeye
24th August 2011, 08:31 AM
Thanks BigCat for that, i was wondering about the old mariners who just casted a mast connected chain over board and that was it.:)

Well i was wondering if one just fixed a chain from the mast footing plate through the super structure hanging in the water if that will not be a quick solution? I am sure it must be short enough not to hit the hulls on either side!:D

What other downside can there be?:eek:

BigCat
24th August 2011, 09:12 PM
Thanks BigCat for that, i was wondering about the old mariners who just casted a mast connected chain over board and that was it.:)

Well i was wondering if one just fixed a chain from the mast footing plate through the super structure hanging in the water if that will not be a quick solution? I am sure it must be short enough not to hit the hulls on either side!:D

What other downside can there be?:eek:

Hi, Popeye - On my old Boat, Batwing, a junk rigged monohull with solid wood masts, I rigged a temporary solution - I bolted a 6 foot aluminum tube to a copper wire about 3/16" diameter. I lashed the tube like a burgee stick, that is tied at the bottom and middle, so that when hoisted aloft on an endless line, the top of the tube stuck above the mast. The wire was long enough to trail in the water 10 feet or so.

While in a squall near the equator in the western Pacific, near Tuvalu, I heard a crackling noise. I went on deck and saw St. Elmo's fire dancing at the mast head around the jury rigged tube. We weren't hit by lightning. (Also called ball lightning, it's said to be the start of a lightning strike.)

My guess is, that was better than nothing, but not as good as a proper permanent system, which is supposed to be at least a square foot in size. Studies show that the effective part of the system is the edges of the plate, so a long strip should be better than a square plate, for a given area of copper. On a catamaran with a mast on the bridge deck, you have a dilemma - no hull directly under the mast, so lightning has to turn at quite an angle to reach a copper plate. Steel is quite a bit less conductive than copper.

Perhaps one could have a hinging aluminum tube under the bridgedeck that hinged down into the water. Better than nothing, but how good, I couldn't say. Any metal should be either untreated or tinned - not anodized or painted.

2hulls
24th August 2011, 10:09 PM
What other downside can there be?:eek:

Given the overall mystery regarding lightning, one cannot discount the arguement that grounding attempts make a grounded boat a more attractive target.

But we should encourage all do-it-yourself research. We must learn from the mistakes of others because we don't have time to make them all ourselves. :D

Repeating my conclusion about lightning strike prevention/defense: if something was known to work, insurance companies would require it.

2 Hulls Dave

BigCat
24th August 2011, 10:51 PM
Repeating my conclusion about lightning strike prevention/defense: if something was known to work, insurance companies would require it.

2 Hulls Dave The US Coast Guard requires lightning protection, on vessels licensed to carry paying passengers in the US.

2hulls
24th August 2011, 11:31 PM
The US Coast Guard requires lightning protection, on vessels licensed to carry paying passengers in the US.

OK, I didn't know that.

What is required for sailing vessels?

The fact that insurance companies don't require anything for what must be their most expensive claimed accident type (on private sailing vessels) speaks volumes.

2 Hulls Dave

BigCat
24th August 2011, 11:44 PM
OK, I didn't know that.

What is required for sailing vessels?

2 Hulls Dave The Coast Guard actually requires very little of yachts, sail or power, of any kind over some twenty odd feet (I forget the exact size.) They concentrate on commercial vessels and small craft. Yachts have to have life vests, a horn, a fire extinguisher, a sign forbidding discharge of oils and oily water, and not much more.

2hulls
25th August 2011, 12:00 AM
The Coast Guard actually requires very little of yachts, sail or power, of any kind over some twenty odd feet (I forget the exact size.) They concentrate on commercial vessels and small craft. Yachts have to have life vests, a horn, a fire extinguisher, a sign forbidding discharge of oils and oily water, and not much more.

I know very well what is required for private yachts. :D

What I meant was what is required for lightning protection/prevention on sailing vessels licensed to carry paying passengers, as you stated earlier?

2 Hulls Dave

BigCat
25th August 2011, 12:23 AM
I know very well what is required for private yachts. :D

What I meant was what is required for lightning protection/prevention on sailing vessels licensed to carry paying passengers, as you stated earlier?

2 Hulls Dave

http://www.uscg.mil/petaluma/TPF/ET_SMS/documents/ET2Unit4Vol2Pamphlet3-01-07.pdf

Page 39 and subsequent. Huge cable; 0000 AWG - about .52" diameter cable. Apparently, cable diameters are given in solid rod sizes, and you have to convert to wire, oddly enough. Also called 4/0. Biggest commonly available, and you have to find tinned wire.

JustCatamarans
25th August 2011, 02:10 PM
Over the years we have repaired a number of cats that have been struck, some of them had diffusers etc, others have been damaged from proximity strikes. We also had a cat on the hard next to a huge monohull with a lot taller rig than the cat, and the the cat got hit, we could not figure out where the charge exited the boat, but when in the slings, we found burn holes through the hull where the jackstands were.
Another boat was unattended at dock, the charge exited through a thru-hull in the bow storage area, a spinnaker was on top of the thru-hull, the spinnaker was set on fire and tried hard to set the boat alight, but fortunately the hatch was closed and lack of o2 extinguished it.
My opinion is that the grounding od the mast/shrouds with large cables straight into the water would be the best, but I cannot see one walking away with no damage.
Also a 1/2 boat(mono) Swan with carbon rig, got hit, $250k later and one week before insurance signoff, got hit a 2nd time:(
Kent

2hulls
25th August 2011, 03:48 PM
http://www.uscg.mil/petaluma/TPF/ET_SMS/documents/ET2Unit4Vol2Pamphlet3-01-07.pdf

Page 39 and subsequent. Huge cable; 0000 AWG - about .52" diameter cable. Apparently, cable diameters are given in solid rod sizes, and you have to convert to wire, oddly enough. Also called 4/0. Biggest commonly available, and you have to find tinned wire.

That publication is a training document for Coasties for grounding system inspections on all sorts of "facilities" - including buildings - when grounding protection is required by some other requirement. This doesn't necessarily imply that the methods described represent CG requirements applicable to for-hire sailing vessels.

I will research this on my own later.....

2 Hulls Dave

BigCat
25th August 2011, 10:31 PM
That publication is a training document for Coasties for grounding system inspections on all sorts of "facilities" - including buildings - when grounding protection is required by some other requirement. This doesn't necessarily imply that the methods described represent CG requirements applicable to for-hire sailing vessels.

I will research this on my own later.....

2 Hulls Dave You didn't read it very closely, I suspect. This document gives what guidance the Coast Guard has to offer on the subject. The Coast Guard doesn't inspect buildings.

2hulls
25th August 2011, 10:58 PM
The Coast Guard doesn't inspect buildings.

You didn't read it very closely, I suspect. :D

I suppose they inspect their own buildings. This document clearly covers buildings as well as ships.

No where are sailing vessels mentioned.

2 Hulls Dave

BigCat
25th August 2011, 11:11 PM
You didn't read it very closely, I suspect. :D

No where are sailing vessels mentioned.

2 Hulls Dave

It mentions masts. The Coast Guard (Actually the CFRs,) rarely mention sailing vessels. In general, sailing vessels must meet the requirements of power vessels. There are very few rules specific to sailing vessels, and only one relating specifically to sailing catamarans, that which relates permitted sail area to stability factors. I have had a sailing catamaran design of mine reviewed and approved by the Coast Guard. It's a quarter of an inch thick. The CFRs are a disorganized mess, as they grew layer by layer, over time. Guidance for training personnel is the closest thing to a rationally organized collection of information.

mikereed100
26th August 2011, 02:14 AM
So little is actually known about lightning strikes on sailboats. How does one conduct research? At best we can look at past incidents to see if we can identify patterns but as far as I know, the only definite conclusion so far is that cats seem to be hit more than monos. Does grounding the rig decrease damage in a strike? Does it increase your chances of being hit? Dave's point that insurance companies have no requirements for lightning protection is well taken.

I see a lot of cats with chain running from their cap shrouds to the water, but I wonder if this is more optimism than substance. The aluminum mast is something like 10x more conductive than the stainless shrouds and chain provides very little surface contact between links for conduction. If you were lightning which path would you choose?

I think if one opts for grounding a better choice would be 2/0 or 4/0 battery cable bolted to the mast. A simple PVC tube could be glassed through the deck with the cable passing through it into the water. The insulation could be stripped from the cable where it contacts the water and a lug placed at the end. A line tied to the lug could be run over the forward crossbeam so that the cable could be lifted clear of the water in good weather.

I have my doubts that grounding provides benefit, but as I sit here typing this in a thunderstorm it has a certain appeal.

Mike

ColdFusion
26th August 2011, 09:01 AM
I think if one opts for grounding a better choice would be 2/0 or 4/0 battery cable bolted to the mast. A simple PVC tube could be glassed through the deck with the cable passing through it into the water. The insulation could be stripped from the cable where it contacts the water and a lug placed at the end. A line tied to the lug could be run over the forward crossbeam so that the cable could be lifted clear of the water in good weather.

I have my doubts that grounding provides benefit, but as I sit here typing this in a thunderstorm it has a certain appeal.

+1

I share your doubts about the benefit of grounding, but for catamaran owners wishing to provide some form of most-direct-route-to-earth grounding from the mast, I think your solution is the best I've heard to date.

Popeye
27th August 2011, 09:28 PM
After a whole lot of research i came to the following conclusion:

1. It seems that electrical bolt in the majority of case run in a straight
line once they struck.

2. A aluminium mast serves as a conductor of the lightning bolt and it is advised
to extend the top of the mast with by a meter with a aluminium rod
of about a 50 - a 60 cm diameter.

3. Where the mast footing is connected to the shroud on the super structure you need
to extend a aluminium rod right through to either a) the saloon
floor and into the sea water or b) connect a chain to the rod
extending into the water, just long enough not to bang against the
hulls.

4. The chain or aluminium rod extending into the sea water should not be
anodised in any way. As Mike suggest if it is a batery cable or a chain rigging it with a rope so one can heave it out of the water sounds very appealing.

In part the philosophy behind this is the old time mariners who just connected a chain to the mast and casted it overboard. This is not the alfa and omega in dealing with a lightning strike but perhaps the simplest and cheapest of at least doing something rather than doing nothing. As far as can tell there is no firm way in dealing with a lightning strike so i hope this is of some help to someone.:)

James Val Jackson
28th August 2011, 02:32 AM
After a whole lot of research i came to the following conclusion:

1. It seems that electrical bolt in the majority of case run in a straight
line once they struck.

2. A aluminium mast serves as a conductor of the lightning bolt and it is advised
to extend the top of the mast with by a meter with a aluminium rod
of about a 50 - a 60 cm diameter.

3. Where the mast footing is connected to the shroud on the super structure you need
to extend a aluminium rod right through to either a) the saloon
floor and into the sea water or b) connect a chain to the rod
extending into the water, just long enough not to bang against the
hulls.

4. The chain or aluminium rod extending into the sea water should not be
anodised in any way. As Mike suggest if it is a batery cable or a chain rigging it with a rope so one can heave it out of the water sounds very appealing.

In part the philosophy behind this is the old time mariners who just connected a chain to the mast and casted it overboard. This is not the alfa and omega in dealing with a lightning strike but perhaps the simplest and cheapest of at least doing something rather than doing nothing. As far as can tell there is no firm way in dealing with a lightning strike so i hope this is of some help to someone.:)

G'day bloke. Thanks for all the time & effort you have put into this subject. As I live, sail, race & cruise - in one of the 'hotest' :eek: lightening strike areas in the world - I'd rather take precautions & not need them that the other way around :o causing $10's of k 's of possible preventable unnecessary costs. THANKS :D

Re # 2; One - I thought the material best to use was copper or bronze rod?? :confused: I also thought the dia was something like 38 mm??? :confused: I like the 1 mtr above highest instruments on the top of the mast - but not the weight of course. :(

# 3; I get all this part :cool:

# 4; I thought the ground end (earth/water) was recommended to be 1 sq ft (144 sq inches) preferably 2" wide x 6' long (the releast/escape of the lightening strike power is said to be from the edge of the plate - ie - 4' compared to 12'4" - edge length) :confused: & to be a copper plate of 1/4" thick suspended 3/8" off the hull surface?? :confused: I'm sure I've collected all this info from the extensive 'lightening strike' forums across the web. :confused: :o :rolleyes:
All of this - if we can get it as correct as possible is of great significance to me & I'm sure many others. I for one sure can't afford the cost of replacing all that electronic gear &/or whole/ or part of my yacht. :eek: :eek:

Thanks again Niel for all your work with this very vexing problem. Ciao, james

Popeye
28th August 2011, 07:31 AM
Hi James,

With reference to #2 the extention above the mast. I am told that alumunium is a excellent conducter and the material is light.

With reference to # 4 Eveywhere i enquired searched and discussed i was informed that a lightning strike run in a straight line. The intensity of the energy cannot be relayed in angles so my initial idea of having copper ground plates on the mini keels would be a waste of time and money!:eek: In theory that might have worked for a 220volt relay but not relaying that animal! It has been said if one can harness a lightning strike you can supply New York with electricity for a whole week!

I am of opinion that extending a mast through the super structure right into the water with a chain running in the water is as good as any other precaution which in itself is a whole lot better than doing nothing.;) And it is relatively cost effective. A former post suggested fixing a line to the chain to lower it into the water when needed. A good idea!:D Thanks Mike!

Please remeber this is my penny's worth, not the solution to such a complex problem!

2hulls
28th August 2011, 12:23 PM
I am of opinion that extending a mast through the super structure right into the water with a chain running in the water is as good as any other precaution which in itself is a whole lot better than doing nothing.;)

I strongly recommend you install such a device - and hopefully convince others to do so - and over time we may see whether it better than nothing or not. Nothing, for now, still seems to be as good as anything else....

2 Hulls Dave

Popeye
28th August 2011, 05:29 PM
Thanks Dave i most certainly will and keep the forum informed.... after a electrical storm .... and if i get struck!!!!! .....:eek: God forbid!!!! ..... That is if i live to tell the tale and the insurance companies paid my claim::)

2hulls
28th August 2011, 05:37 PM
In the meantime, be sure to tell the insurance company you have installed this system and ask if you'll get a discount on your insurance premium because of it - or whether they want to charge you more. Let us know what they say. :D

2 Hulls Dave

rgesner
30th November 2011, 09:15 PM
Bare aluminum quickly oxidizes and aluminum oxide acts as an insulator. When house wiring with aluminum cable, you have to wirebrush off the oxide and coat it with corrosion preventative gunk immediately before lugging it down.

A copper cable could be dangled in the water from under the mast plate when storms threaten, but could be lashed back astern tight to the underside of the bridgedeck when not needed.


<snip>Perhaps one could have a hinging aluminum tube under the bridgedeck that hinged down into the water. Better than nothing, but how good, I couldn't say. Any metal should be either untreated or tinned - not anodized or painted.

JustCatamarans
30th November 2011, 09:23 PM
We have just started on a lightning repair on a cat, in the foreground of the picture of what is left of the masthead vhf antenna, in the background is a diffuser - go figure?
Kent

dmmbruce
30th November 2011, 09:31 PM
We have just started on a lightning repair on a cat, in the foreground of the picture of what is left of the masthead vhf antenna, in the background is a diffuser - go figure?
Kent

I don't understand what you mean by 'go figure'. Do you mean that the vhf did a good job as a lightning conductor. Or do you mean that the diffuser did nothing. Or , , , ?

Mike

JustCatamarans
30th November 2011, 09:35 PM
I don't understand what you mean by 'go figure'. Do you mean that the vhf did a good job as a lightning conductor. Or do you mean that the diffuser did nothing. Or , , , ?

Mike

vhf DID A WONDERFUL JOB OF CONDUCTING SURGE TO BOATS SYSTEM, APPEARS DIFFUSER DIDNT DIFFUSE OR WAS TOO LOW
::)

dmmbruce
30th November 2011, 09:50 PM
vhf DID A WONDERFUL JOB OF CONDUCTING SURGE TO BOATS SYSTEM, APPEARS DIFFUSER DIDNT DIFFUSE OR WAS TOO LOW
::)

Ah! Understood, yes. Thanks! :D

Mike

BigCat
30th November 2011, 10:26 PM
Bare aluminum quickly oxidizes and aluminum oxide acts as an insulator. When house wiring with aluminum cable, you have to wirebrush off the oxide and coat it with corrosion preventative gunk immediately before lugging it down.

A copper cable could be dangled in the water from under the mast plate when storms threaten, but could be lashed back astern tight to the underside of the bridgedeck when not needed.

For that matter, copper also oxidizes, creating a blue surface. I guess the best conductor would be aluminum or copper plated with tin. Marine wiring is supposed to be tinned.

downunder
30th November 2011, 11:47 PM
Don't quote me as an authority however i read an article by Nigel calder that indicated he did some significant research for the US boating standards authority he was involved with talking with experts and could not come up with anything to protect you.

Seems to me to be little reliable info ????????????? :confused::confused:

Just take your chances. Just catamarans example showed at mast diffuser did not work.

BigCat
1st December 2011, 12:14 AM
Well, there's this: http://www.marinelightning.com/

They have a section devoted to catamarans:

http://www.marinelightning.com/catamaran/index.html

They are, of course, selling their products, so caveat lector.

Tropic Cat
2nd December 2011, 01:23 AM
[QUOTE=Popeye;40159....
Fit a solid copper rod to the mast extending .5 meter above the mast runnining though the bulkhead till under the saloon floor where it will split in two, fololwing the contours all the way down to the mini keels where its attached to a copper plate that is attached to the keels. Between the copper plate and the glassfibre keel is a thick rubber to avoid a flash back of the elctrical bolt. On deck run a copper band to either side where any high point stainless Steel may be.

Isolate the engines with its owns startup batery and run earth wires to the the dissapating cable....[/QUOTE]

Why??

I've been struck by lightning on my Catalac. It hit the mast near the top and exited the boat through the propeller shafts. Showered me and the admiral with hot metal from what it blew off the top of the mast,

If your mast is aluminum, why parallel a copper pipe? You already have a good conductor. Again, your engines are already in the water, why isolate them? Just figure a way to connect them together.

Catamarans are getting hit more than monohulls these days. When I researched it (after I was struck of course), I discovered that the one common denominator was the unlucky catamarans were almost always in shallow water at the time the storm cells rolled in. As was I when I was hit.

Having a fathom or two under the keels is the best lightning protection I can recommend.

SteveH
2nd December 2011, 09:43 AM
vhf DID A WONDERFUL JOB OF CONDUCTING SURGE TO BOATS SYSTEM, APPEARS DIFFUSER DIDNT DIFFUSE OR WAS TOO LOW
::)

So perhaps the best bet is to throw the VHF over the side on the end of its cable! ::)

Tropic Cat
2nd December 2011, 01:39 PM
If you are struck by lightning, anything connected to the boat electrical system at the time of the strike is going to be damaged / destroyed. All of my breakers did trip, but all had been flashed over and were covered in carbon. They in fact offered no protection at all. All thermal in-line fuses were blown but again, did not protect any of the gear they were supposed to protect.

The boat lightning precautions are to direct the charge through the least destructive path to water to prevent hull damage. I believe we all have a natural cone of safety for crew in that our masts are stayed with steel wire. However, the high voltage has to be given a safe way to get to water.

In my case, what was interesting is that battery operated devices like cell phones, digital camera and hand held GPS, which were turned on, and on the salon table were undamaged.

BigCat
2nd December 2011, 07:48 PM
what was interesting is that battery operated devices like cell phones, digital camera and hand held GPS, which were turned on, and on the salon table were undamaged. Significant information - in other words, use portable stuff where possible, and unplug electronics if you think lightning strikes might be immanent - not that forewarning is always given.

Tropic Cat
2nd December 2011, 09:22 PM
My Lightning strike details (http://www.catamaransite.com/lightning.html)

With photos

LifePart2
30th January 2013, 07:06 PM
I know this is an old thread, but it is still a current challenge!

The challenge with cats is that the mast foot is a long way from any water, in any direction. Having the current travel the length of the boat to reach the engines doesn't seem like a good idea to me.

So here is the system I am planning for my Leopard 42:

1) An aluminium rod at the top of the mast to extend its reach beyond the other fittings.
2) a heavy duty copper cable that temporarily bolts to the bottom of the mast. The cable is 7m long, and has a 1m x 10cm aluminum plate bolted to the end of it.

If I find myself in a storm area I will go forward, bold the cable to the mast, then take that cable forward and drop it through the anchor hole into the water so that the big metal plate is in the water.

Yes, there are still some bends in the system, but it seems to me that this would provide the most direct route from mast tip to water.

Ideally one would also want a simple way to disconnect the wiring at the foot of the mast so that the connection between mast and the rest of the DC wiring is interrupted.

Any thoughts on this?

Noel

BigCat
30th January 2013, 08:01 PM
I know this is an old thread, but it is still a current challenge!

The challenge with cats is that the mast foot is a long way from any water, in any direction. Having the current travel the length of the boat to reach the engines doesn't seem like a good idea to me.

So here is the system I am planning for my Leopard 42:

1) An aluminium rod at the top of the mast to extend its reach beyond the other fittings.
2) a heavy duty copper cable that temporarily bolts to the bottom of the mast. The cable is 7m long, and has a 1m x 10cm aluminum plate bolted to the end of it.

If I find myself in a storm area I will go forward, bold the cable to the mast, then take that cable forward and drop it through the anchor hole into the water so that the big metal plate is in the water.

Yes, there are still some bends in the system, but it seems to me that this would provide the most direct route from mast tip to water.

Ideally one would also want a simple way to disconnect the wiring at the foot of the mast so that the connection between mast and the rest of the DC wiring is interrupted.

Any thoughts on this?

Noel

Noel, Why not a permanent set up, with a hole directly under the mast, and a line attached to the cable end to pull it up and aft along the underside of the deck? That's more direct for the lightning to travel, which is a very good thing, and it keeps you from having to handle the conductor during a lightning storm, an even better thing. By the way, a long strip is better than a copper plate. The effective portion of the plate is the edges of it. I would make the whole thing out of copper.

rgesner
30th January 2013, 08:36 PM
Noel, Why not a permanent set up, with a hole directly under the mast, and a line attached to the cable end to pull it up and aft along the underside of the deck? That's more direct for the lightning to travel, which is a very good thing, and it keeps you from having to handle the conductor during a lightning storm, an even better thing. By the way, a long strip is better than a copper plate. The effective portion of the plate is the edges of it. I would make the whole thing out of copper.

That's almost exactly what I was going to say, because the strike will resist any bends in its path.
However, I was wondering if a strip of bronze might be better than copper, to resist corrosion?

Rusty

LifePart2
30th January 2013, 08:37 PM
Our mast is stepped on the roof of the salon, and is then supported underneath with a stainless steel pipe which, in turn, sits on the bottom crossbeam of the bridge deck. So do you mean attach it through the underside of the bridge deck to the stainless steel pipe? That would, indeed, be the only way to get a straight line from mast to water.

That would be an interesting idea as one could then just pull the cable aft along the bottom of the bridgedeck when not in use.

But, stainless is not a great conductor, and I think there is probably glassfibre between the mast foot and the stainless pipe. And, of course, we would have to drill through the fibreglass underneath the stainless pipe to have access to the outside, where we would attach the cable.

Also, the number of times we actually need it, I am not sure we really need to have it permanently connected.

It was for these reasons that I came up with the idea of bolting a cable to the foot of the mast and then dropping it in the water at the nearest point available.

Copper is heavy. Aluminum has almost the same conductivity, and is a lot lighter. The reason for the 1m x 30cm plate is to give the the surface area recommended by Calder, while also having long edges.

If it is used only occasionally, then corrosion is not a concern.

Noel

Woods Designs
30th January 2013, 09:30 PM
I only just saw this thread for the first time

You may find this article useful

http://sailingcatamarans.com/index.php/articles/11-technical-articles/47-lightning-strikes-on-eclipse-2003

The two most useful websites are

http://www.marinelightning.com/

and

http://www.strikeshield.com/ by seylor marine

Richard Woods of Woods Designs

www.sailingcatamarans.com (http://www.sailingcatamarans.com)

georgetheleo
30th January 2013, 09:54 PM
Just to put my 10 cents worth in (for the non uk members ) or 2 bobs worth,

as far as I was aware, there is NO full proof wayof protecting a boat from a strike.

thats becouse weknow What it is but do NOT know how, why or what triggers it.

I seen boats almost disintergtrate after a strike. and others with superficial damage. both wooden masts, no lightning rod.it does depend where the strike jumps too.

the only safe way is to have a metal boat. stillgetstruck but being a faraday cage there is noproblems.

I have actually sailed through the steam of where a strike has hit the water maybe 5 metres in front of us. we had ally mast, earthed rigging too plates , serious yacht (been round the world twice) why did it not hit us???

there are lots of theorys. why muck about going through a metel oxidised mast when it can go to the perfect ground.
aargh ------but lightning flows upwards, ok so why does it trees and go DOWN to the ground---

like I said ---no one really knows.

I have sailed in lots of thunder storms and not been hit.
my mate has been hit twice. (i dont go sailing with him:eek::eek:)

I think its one of those things that you do what you feel is best. wether it actually does any good---who knows. difficult to prove. and a good placibo effect

the only think I do is put a spare hand held vhf, gps, and mobile phone in the oven. put up an umbrella-------(joke) and wach the show

Kim
::)Lightning goes both ways

LifePart2
30th January 2013, 09:58 PM
HI Richard,

Nice article, but you don't say how exactly you grounded the bottom of the mast to the sea. The ideal would be to have a conductor that goes right from the mast foot, through the cabin, straight down out of the bottom of the bridgedeck and into the water, but I don't see how to do that practically.

Good idea about having none of the instruments permanently wired in, but a challenge to set that up. I guess one could get some kind of big plug that plugs them all in somehow.

Maybe easier, though would be to have some kind of big plug at the bottom of the mast so that one can quickly disconnect the masthead wires from the rest of the boat. I think I will look into that. I guess a bunch of those 12v connectors used on RV's would do the job.

At least if there is no connection through the mast foot to the 12v wiring, and there is a connection through the mast foot cable to the water, then that latter route should be preferred by the lightning. In theory anyway.:whistling Even if it isn't straight.

Good point about disconnecting the engine battery terminals

My hope is that the handheld GPS and laptop inside the oven would survive, thus still allowing navigation.

I did have a ***tant, but last summer the eyepiece fell off into the water, so then I had to go to my backup nav - the 4 GPS's I have on board. Seriously. Nothing is foolproof!

Noel

I love this emoticon, so I just put it here for fun: ::)

LifePart2
30th January 2013, 10:10 PM
Just as an additional point of interest, we have dynex dux (synthetic) shrouds, not steel ones, so the only additional bit of steel between masthead and deck is the steel forestay.

Based on that article about protecting boats like houses, it might be worth putting an additional rod and ground at the stern arch where our solar panels are. Will think about that too.

Noel

BigCat
31st January 2013, 12:42 AM
That's almost exactly what I was going to say, because the strike will resist any bends in its path.
However, I was wondering if a strip of bronze might be better than copper, to resist corrosion?

Rusty Hi, Rusty - I've never seen bronze recommended for that purpose, which makes me wary.

Tropic Cat
31st January 2013, 01:00 AM
Will this work?


Material IACS % Conductivity chart

Silver 105%
Copper 100%
Gold * 70%
Aluminum 61%
Nickel 22%
Zinc * 27%
Brass 28%
Iron 17%
Tin 15%
Phosphor Bronze 15%
Lead *7%
Nickel Alum. Bronze *7%
Steel 3 to 15%

LifePart2
31st January 2013, 01:24 AM
Wow, one would have thought that bronze would be similar to copper!

So, what I really need is a silver lightning rod. hmmm. If I have it gold plated, then I would eliminate corrosion problems too.

Woods Designs
1st February 2013, 08:38 AM
I hadn't realised until just now that Seyla marine had stopped trading. So sorry about the missing link

We had 2 Strike Shield systems on boats and were never hit with them installed

It comprised a masthead rod with rounded end and a long very thick wire with fancy end fitting that was bolted to the bottom of the mast and hung over the side

A masthead lightning rod should provide a big enough "safety cone" to protect the stern arch

Richard Woods of Woods Designs

www.sailingcatamarans.com

LifePart2
1st February 2013, 05:55 PM
Richard, that is exactly the system I am planning to install:

An aluminum lightning rod at the top ( still have to source this). I am thinking of a 5/8th inch Al rod with smoothed off end, which then bolts to the side of the mast and extends up beyond the antenna.

a big fat heavy cable that attaches to the mast and then drops overboard into the water. I have this. I drilled and taped a hole into the bottom of the mast, so I can just screw in the cable, which has an eye connector at the end, whenever i want to deploy it.

a dissipator at the end of the cable. For this I was planning to use a big sheet of aluminum which provides surface area and edges as per Calder's recommendation of 1/3 sq m (if I remember right). I looked at the Strike Shield system and am rather surprised by the small size of their dissipator.

I don't have steel shrouds. I do have a steel forestay. My understanding of electricity is it doesn't take one route through anything. It takes every route, apportioned according to the resistance. Steels has higher resistance than aluminium, but it is still a conductor. One would expect, therefore, that lightning would go down the mast AND down all available shrouds and stays.

Once it gets to the bottom of them, it then has to find a route to the water. This is where those side flashes that tend to sink boats come in, as the current jumps from the base of the mast/shroud and finds a way to ground. It does this by jumping to any convenient conductor that shortens the path to the water. In the document you linked to, that might be through the anchor chain, water tank etc and then out the side of the hull. In a cat it seems to me that this would include:

Mast foot -> DC wiring at the foot of the mast -> through the whole wiring system -> engine -> prop . This would be the rationale for disconnecting the wiring at the base of the mast. But one would also have to provide an alternative, lower resistance route - ie the cable into the water.

Forestay -> crossbeam -> anchor chain ? then what, since that is probably on the bridge deck, not in a bow as on monohulls. Or perhaps from the crossbeam to the lifelines and toerails to elsewhere.

Shrouds -> lifelines and aluminium toerail -> maybe to the inerior wiring, or the plumbing in the heads -> through hulls or through the engine again.

So, in addition to grounding the base of the mast, I am thinking that perhaps we should also drop a cable into the water from the bottom of the forestay.

I don't have steel shrouds, but if I did, then maybe a cable from the chainplates to the water would also be an idea.

Since the stern arch and bimini are a big steel construction, maybe that should also be grounded in case of a direct hit to them instead of the masthead.

Finally, since the lifelines form an almost complete ring around the boat, does it make sense to join them together? Would that provide a bit of a Faraday cage?

Good to hear you haven't been hit by lightning since you put in the Strike Shield. Of course we have no way of knowing if it actually saved you, or you just weren't a strike target. A bit like my magic stone that seems to be remarkably effective at protecting me from attacks by wild tigers.

So, that is my current thinking and plan. Seems relatively easy to install and deploy.

Have I missed anything? Any comments or improvements? What size and shape plate should I use as a dissipator at the end of my cables? Bearing in mind that I don't want it crashing into my hulls as we are moving along.

Noel

rgesner
1st February 2013, 06:11 PM
I hadn't realised until just now that Seyla marine had stopped trading. So sorry about the missing link
<snip>


Actually, although Strikeshield/Selya products are apparently no longer available and the main home page http://www.strikeshield.com/ of the site looks like it is a dead end, if you click on the tabs of that page, such as Lightning, Grounding, FAQs and even Lightning Protection Products, all the info and images are still there.

I tried to save the whole site as a web archive on my computer for future reference, but they have robot crawler blocks preventing that. In your web browser, you can saveas one page at a time, but the links will point back the online web site, so saving everything will be a tedious process (I will try to do so when I have time, before it all disappears.)

- Rusty

Mr B.
2nd February 2013, 04:30 AM
I would have thought that Fibreglass Catamarans would be insulated against lightning strikes.

The aly mast is about four feet above the water and is not connected to the water,

In a storm, I would be using sails, My motor would not be in the water, as I can lift it clear on Hydraulics,

On anchor, The lightning would travel down the Genoa cable or furler and jump to the anchor chain and then into the water,

Other than thru hulls which are connected to the top of the mast by the electronic GPS Wind instruments, Etc, But thats a long way sideways for the lightning to travel, and very thin wires as well.

A high voltage cable drops onto a car, you are perfectly safe untill you try to get out of the car, Then you earth out the car and you fry, Its insulated by the rubber tyres,

Same as a crane on rubber tyres that hits over head wires, Its insulated untill the driver hits the ground and becomes the earth, = Charcoal Driver,
If he stays in his cab, He is quite safe,

Is lightning one of those things, In the wrong place at the wrong time,
Just one of those things that happen,

From what I have read, Its very hit and miss with Lightning,

But being earthed out, will that increase your chances of being hit, or not,

Will being earthed out, attract a lightning strike more often, as it is the easiest path for the lightning to follow,

Tropic Cat
2nd February 2013, 04:52 AM
I would have thought that Fibreglass Catamarans would be insulated against lightning strikes......

Lightning is a million volts of plasma which has the singular goal of reaching 'ground'. A lightning strike on a fiberglass boat will in all probability hit the top of the aluminum mast. From that point it will travel not only down the mast but also down every metal stay attached to the mast, in all cases heading for the water.

In the posts above this one were discussions of strategies to assist the high voltage to exit the boat gracefully. Meaning with minimal damage. By 'minimal', I mean that every piece of electrical or electronic equipment outside of a faraday cage is damaged or destroyed, but there is no loss of hull integrity.

I've been struck by lightning while motoring through a strong storm cell. I took the hit at the top of the mast. There were 2 of us on board at the time and we felt nothing. No tingle, no electric current, nothing. Even though we were barefoot and soaking wet in the cockpit at the time. But the damage to electrics and electronics was complete, right down to alternators and the starter on my starboard engine. Some things literally blew up.

It's a very real concern here in the tropics and insurance data seems to indicate that catamarans are struck more often than monohulls. Recent data shows that the shallower the water you are anchored in, the more likely you will get hit in a storm.

Hit by lightning (http://www.catamaransite.com/lightning.html)

rgesner
2nd February 2013, 05:05 AM
I would have thought that Fibreglass Catamarans would be insulated against lightning strikes.


Many years ago lightning striking a fiberglass Flying Dutchman blew a row of tiny holes through the hull at the waterline. Electricity seeks the path of least resistance, and sometimes that path may be through an insulator.

Rusty

Woods Designs
2nd February 2013, 12:01 PM
And that's really why catamarans are at more risk. They don't have a big keel sitting under a mast. Mind you, steel boats are still hit by lightning but tend not to get holed

One night we were in a Panamanian anchorage with 10 other boats. 6 were hit by lightning in the same storm. Not us. But the boat next to us was, and he was only 10yds away (we told him he was too near us when he anchored)

Where we lucky, or did the Strike Shield save us?

Richard Woods of Woods Designs
www.sailingcatamarans.com

colemj
2nd February 2013, 08:31 PM
The Strikeshield did not prevent the lighting from striking you - nothing can do that. It is designed to help mitigate serious structural damage if you do get hit.

We were hit in Sept. 2011 with a Strikeshield deployed. We lost almost all electronics, but there was no structural damage to the boat. The electronics were damaged by the lightning getting into the negative side of the electrical system through the VHF coax shield. This was all easily traced.

Suppressors have now been fit to clamp residual voltage spikes on the electrical system and to help hinder the path down the VHF coax. Also, the new N2K network allows all instruments except the radar to be physically electrically isolated by pulling one plug in easy reach. The radar must be disconnected separately.

While the Strikeshield electrode end looks small, it is machined in a shape so as to produce a high total length of sharp edge surface (125" - over 10') - which is the most effective way to dissipate the strike energy to the water.

Mark

Woods Designs
2nd February 2013, 10:25 PM
I should have said that even with the Strike Shield deployed we still disconnected all electronics and put them in our oven (a Faraday cage) and we would disconnect the VHF antenna. We would also disconnect the batteries from the engine. Basically isolating as much as we could

Richard Woods of Woods Designs

www.sailingcatamarans.com

colemj
3rd February 2013, 01:38 PM
You just can't disconnect the VHF and be safe. That would be similar to leaving the electrode end of your Strikeshield inside the boat. If hit by lightning, the coax will guide a good portion of the energy right to where you don't want it and cannot control it. You may be safer leaving it connected, where any lighting energy will find a safer path to ground through the electrical system.

You should consider installing suppressors on the coax in two places - at the antenna base and where the coax enters the boat (ideally above your Strikeshield attachment point, if possible). Provide a safe ground path to water to the suppressors. During a strike, the suppressors will shunt to ground and hopefully greatly attenuate or stop any energy from going further into the boat.

Alternately, connect a heavy wire to both the center and shield conductors of a PL259 (or whatever coax end fittings you use), connect the fitting to the unhooked end of your coax and connect the wire to a safe ground to water.

The first suggestion is permanently in place and always ready. The second suggestion carries the risks of having to be present on the boat, to know when lighting is going to happen (we took a bolt out of the blue), and having your body physically connected to the grounding path while connecting the system during a lightning storm.

Mark

Tropic Cat
3rd February 2013, 02:03 PM
You just can't disconnect the VHF and be safe
I agree completely


You should consider installing suppressors on the coax in two places - at the antenna base and where the coax enters the boat (ideally above your Strikeshield attachment point, if possible). Provide a safe ground path to water to the suppressors. During a strike, the suppressors will shunt to ground and hopefully greatly attenuate or stop any energy from going further into the boat.


Mark, I don't think so. Those cute suppressors would get blown across the salon as there's no way to attach them to heavy enough wire with a straight path (no bends) to make any difference. The high voltage will just flash over them much like it jumps circuit breakers.

From our experience, the only way to protect electronics is to have them completely disconnected from all boat wiring and physically moved to a safe place.

There's a few of us that have been struck and what's interesting is the commonality. If you get lucky (as I did) or carefully prepare, the best you can hope for is to protect hull integrity. That's not a bad thing. Electronics can be replaced.

We haven't even discussed casualties. My admiral has been sailing gun shy ever since our lightning strike experience. Anyone have a cure for that?

LifePart2
3rd February 2013, 06:22 PM
Richard, what physical size is the StrikeShield dissipator?

Here is what I am now thinking for a dissipator:

Get a bunch of star-shaped copper washers. http://www.bokers.com/washers.asp Thread these on to a long copper bolt, spaced out with smaller washers or spacers between them. Then braze them all together with tin.

That should give a chunky unit like the strikeshield with lots of edges. Should be better than a big plate plate.

Now, I know that one cannot have the edges too close together, so anyone have any thoughts about what gap to set between adjacent star washers?

And also what diameter washers, how many of them, and overall length of the unit. That was why I was asking for the size of the StrikeShield one, as that should give a guide.

Thoughts?

Noel

Woods Designs
3rd February 2013, 07:01 PM
Colemj

I see your point re the antenna cable. But then Tropic cat first agrees with you and then says

"From our experience, the only way to protect electronics is to have them completely disconnected from all boat wiring and physically moved to a safe place."

So what happens to the antenna end? Or is a handheld vhf the only answer? Or a powerboat style deck mounted antenna that is so low relative to the mast it is in its "safe cone"

We had two Strike Shields. The first came with a grounding plate about 15in long and 11/2in diameter. The second was shorter, fatter and had sharp points (from memory) so I guess like Colemj's

My thought had been to make a grounding plate with "sawblade" style teeth, but Dr. Ewen Thomson of marinelightning.com, with whom I had long correspondence, said that wouldn't work

I suggest contacting him for his comments

Richard Woods of Woods Designs

www.sailingcatamarans.com

Woods Designs
3rd February 2013, 07:08 PM
There's a few of us that have been struck and what's interesting is the commonality.
We haven't even discussed casualties. My admiral has been sailing gun shy ever since our lightning strike experience. Anyone have a cure for that?

That's why I finished my Lightning Strike article

http://sailingcatamarans.com/index.php/articles/11-technical-articles/47-lightning-strikes-on-eclipse-2003

by saying

"Finally, unlike you, I have already been hit, so there is one more thing I do when lightning threatens. I hide under the bed clothes. And maybe that's the lasting legacy of my lightning strike. One year on, my boat has been fully repaired, but (like the shell shock victims of WW1) the psychological effects of the worst day of my life still haunt me."

The answer to get your admiral sailing again is easy. Move house.

(Seriously, it's why we have a home in the PNW not Florida) Three thunderstorms in 7 years

Richard Woods of Woods Designs

www.sailingcatamarans.com (http://www.sailingcatamarans.com)

LifePart2
3rd February 2013, 07:22 PM
Thanks, I will contact Dr. Ewan and see what he has to say.

BTW, Richard, will you be at the Vancouver Boat Show this week? We are going up for Thursday. If you are around would be a delight to meet you. PM me if you are.

Noel

colemj
3rd February 2013, 10:48 PM
I agree completely

Mark, I don't think so. Those cute suppressors would get blown across the salon as there's no way to attach them to heavy enough wire with a straight path (no bends) to make any difference. The high voltage will just flash over them much like it jumps circuit breakers.

From our experience, the only way to protect electronics is to have them completely disconnected from all boat wiring and physically moved to a safe place.

There's a few of us that have been struck and what's interesting is the commonality. If you get lucky (as I did) or carefully prepare, the best you can hope for is to protect hull integrity. That's not a bad thing. Electronics can be replaced.

We haven't even discussed casualties. My admiral has been sailing gun shy ever since our lightning strike experience. Anyone have a cure for that?

The coax lightning suppressors I installed have a beefy terminal connection that takes quite a large wire. The one at the antenna end is grounded directly to the mast with a 1" length of 8g wire - straight with no bends. These are in use in most commercial radio installations. They are not cute, but are pretty in a brutish type of way.

Perhaps we are not talking about the same type of thing?

Then there is protecting the electrical panel, or individual circuits. Panel lightning surge protectors are common installations in houses and certainly rated for handling expected loads. Circuit lightning surge protectors help keep the entire internet running, not to mention all corporate data centers.

The panel/circuit protectors do not expect a direct lighting strike like the coax ones. They are designed to quickly (micro to milliseconds) clamp a few thousand volts and a couple hundred amps for a second or two and shunt them safely to ground. It is expected that the main strike will be mitigated by other measures (strikeshield, coax clamps, etc) Their connections and wiring are easily within these parameters.

Check out Polyphasor or Midnight Solar for examples and details.

As for protecting electronics by totally removing them and placing them in an oven: During our strike, none of this was done. All of our wired electronics were lost, as well as much of the electrical. However, we had two computers and 2 cell phones plugged into the running inverter at the time. The inverter smoked (literally), but the computers and phones were unharmed.

Two cell phones, two additional computers, two handheld GPS's, a HH VHF, many hard drives, a TV, 2 routers, a 3G mifi, an iPod, 4 calculators, 3 cameras, 2 Kindles and various other small electronics were simply lying about the cabin and were unharmed. Some of them were laying right next to the compression post. Many of them were laying within 6" of the VHF coax which brought the strike into the boat.

Two isolated iPods kept in a cupboard mostly surrounded by metal on almost all sides and additionally positioned under our aluminum bimini were toast. One had a hole blown right through its screen.

An oven is not a faraday cage for lightning frequencies. It is not continuous, is not constructed of the correct materials and is most likely not grounded. A microwave is probably a better bet if you want to stash electronics there.

The best protection against lighting is a good insurance policy, or the ability to personally part with the money easily.

After 1.5 years since the strike, we curl up into a fetal position and start wimpering whenever a loud bang or bright flash occurs anywhere. We are useless during fireworks...

Mark

colemj
3rd February 2013, 11:00 PM
So what happens to the antenna end? Or is a handheld vhf the only answer? Or a powerboat style deck mounted antenna that is so low relative to the mast it is in its "safe cone"

We had two Strike Shields. The first came with a grounding plate about 15in long and 11/2in diameter. The second was shorter, fatter and had sharp points (from memory) so I guess like Colemj's


Certainly, a VHF antenna mounted below the mast would be the best protection. However, it is not always the best for making radio contacts (on the other hand, after listening to the inane VHF chatter the past couple of days here, I am about to remount my antenna to the bilge). That depends on the boat - a 9-12db whip on an arch 10' off the water on a catamaran would probably work well. A 3db whip on the deck of a monohull not so well.

Next best thing is to attempt protection by the manner I suggested earlier.

A HH VHF is about the only way of guaranteeing no lighting on coax, but is not really the best all-round option for practicality.

Our Strikeshield electrode is roughly a cylinder ~7-8" long and machined from solid copper to have 18 sharp edges in it along its length, as well as a sharp point on the end of the cylinder. It is difficult to describe in words, but the website used to have good pictures and descriptions of it.

Mark

LifePart2
3rd February 2013, 11:58 PM
The picture of the strikeshield dissipator is still up on their website http://www.strikeshield.com/Lightning%20Protection%20Products/dissipater but it didn't give any sizes, so thanks Mark

I am totally lost on the VHF / wiring protection discussion.

It seems to me there are two issues:

1) lightning actually uses the boat's wiring or antenna coax as a route to ground.
2) the huge currents from lightning induce currents in nearby electrical circuits.

We try to prevent (1) by providing a better path to earth (the strikeshield method) and physically disconnecting wires at the mast foot and at the engine. Correct? I presume that also applies to the VHF coax coming out of the bottom of the mast? Are you suggesting we also have to ground the coax sheath as well?

Don't know how we prevent (2) other than by a Faraday cage. Which leaves all our permanently installed instruments vulnerable. Or is this what you are trying to achieve with surge protectors etc? Where would one put those?

Am surprised to hear that the oven doesn't work as a Faraday cage. Is that really true? So unless it is grounded, we are better off NOT putting things in the oven?

Noel :confused:

Tropic Cat
4th February 2013, 02:09 AM
....Two cell phones, two additional computers, two handheld GPS's, a HH VHF, many hard drives, a TV, 2 routers, a 3G mifi, an iPod, 4 calculators, 3 cameras, 2 Kindles and various other small electronics were simply lying about the cabin and were unharmed...

Mark

Same here. Hand held GPS, 2 cell phones, Canon Rebel camera, etc...all left on the salon table, all running on their batteries and all were perfectly OK. In the end, it was only items connected to the boat wiring which were effected. Of those, I lost everything.

Changing the subject... this is the first Super Bowl I can re ember which has been delayed because the stadium lights went off! Lightning?

Sully
4th February 2013, 02:15 AM
A microwave (or oven without any window) is a good faraday cage.

Woods Designs
4th February 2013, 09:42 AM
BTW, Richard, will you be at the Vancouver Boat Show this week? We are going up for Thursday. If you are around would be a delight to meet you. PM me if you are.

Noel

No, I am in the UK right now. We only spend summers in BC as we are not Canadians and summer seems to us to be the best time to sail there!

We have a summer house on Saturna, Gulf Islands. We expect to be there from early April, the first multihull meeting is on Pender Island mid May

Richard Woods of Woods Designs

www.sailingcatamarans.com (http://www.sailingcatamarans.com)

HappyEnding
5th February 2013, 01:17 AM
A microwave (or oven without any window) is a good faraday cage.

What if the oven is plugged into the 110 ac circuit? and does being on or off shore powermake a difference???

iXenophon
8th February 2013, 01:58 PM
I was struck last June.
later it was determined that I was not actually "struck", but is what they call "lightning event".
I read much about it, and asked many insurance, repair, and surveyors. Seems to be very prevalent issue. And there is no universal way for prevention, or mitigation. In fact if there were the insurance companies would demand it. It is capricious, and entirely random who it hits, and what effect it has.

My issue was extremely mild compared to what can happen - up to destroying all engines/generators, welding chain together in locker, burning furled sails - blowing hole thru side of boat, etc, etc...(whether they have lightning thingies or not). Electronic loss is minor compared to all these...

In any case I determined that something turned on was more susceptible, and anything (VHF, AIS) connected to VHF coax was more susceptible in my "event". I would imagine a direct hit would zap everything regardless. But I wish to do what I can to mitigate an "event" (probably just induced current).

Since the mast was without systems for some time waiting for un-stepping and inspection, I purchased a cabin top VHF aerial and decided to permanently mount it on saloon roof. I leave lower one connected,usually, and would only connect the upper when necessary. (both disconnected at anchor etc). the range is more than adequate for most coastal sailing.

I installed a #4 cable from top of mast - directly thru the chain locker and into water. It is very straight. And permanently deployed (moving/anchor). It has no vertical post on top or dissipater/plate in the water. I'm no expert - may be useless without these things - but it does provide path to water other than coax. I also made best efforts to provide central system for disconnection of all power, quickly and easily (for anyone) - vessel had many hidden breakers etc - trips to the engine room to disconnect(very dangerous). I also installed remote switches to engines and generator (and everything connected to those starting batteries) - these guys:
http://bluesea.com/category/6/productline/385
I have them all off by default - always.

I also wanted to make sure all grounding and bonding was as good as can be - for all 4 reasons - electrolysis, radio interference, safety, and lightning.
I read this from Stan Honey:
http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorView?langId=-1&storeId=11151&page=Marine-Grounding-Systems#.URT9BKVX1IE
and Calder's info.

Honey suggests (from memory) that the mast grounding should travel directly from mast top in direct line to water(mast-top to water) thru mast stepped keel, etc. And should NOT be connected to rest of grounding system. And there should then only be one location to water for rest of grounding system (thru engine).
makes sense to me - except catamarans have 2 engines, and no keel under mast.
So not sure about the 2 engine issue. otherwise I have it as best I can - for now...
cheers

Gringo
8th February 2013, 02:48 PM
We got hit while eating lunch sitting gently aground on soft smooth sand just north of Chub Cay in the Bahamas, waiting for the tide.

It was definitely a strike. There is no doubt about it. It blew the VHF antenna right off the mast, right above our heads. La Gringa's ear rang for about 24 hours. We both got mild shocks, even sitting in the galley next to the compression post.

iXenophon
8th February 2013, 03:09 PM
the VHF aerial was blasted off.
tricolor exploded.
mast/deck light (half way up mast ) exploded.
some filler in carbon mast - blown out -(apparently structure ok)
But, the thermal surveyor and insurance surveyor stated was lightning "event" (whatever that means)...
and they represent insurance company - not me...
I was aboard and was very loud "crack" noise...

Tropic Cat
8th February 2013, 05:25 PM
lightning event? hmm.....

Gringo, tell La Gringa that my left ear hasn't stopped ringing since we were struck

I too was in shallow water when struck. I think this is the reason more cats are hit vs monohulls. We're in shallow water because we can be...

Talbot
11th February 2013, 11:13 AM
I too was in shallow water when struck. I think this is the reason more cats are hit vs monohulls. We're in shallow water because we can be...

I think that this is the crucial fact. Stay in deeper water where possible.

Sandy Daugherty
11th February 2013, 05:48 PM
You are all wrong: wrong, wrong, WRONG! ::)

Lightning is Mother Nature's way of expressing her opinion of science in general and the human error of assuming anything natural is subject to rational explanation.

She considers all attempts to control her freedom of expression to be contempt of her power, and as we all know, Hell hath no fury like a woman scorned.

If you can grasp this fundamental truth, you are prepared to understand several profound observations:

Have you seen lightning? Did it look like a straight line to you?
How about those wire duster thingies that were the first object melted?
Why does one 'event' take out every integrated circuit on board when another just blows hole around the waterline and leaves an odd assortment of electronic goodies unphased? And how does a strike on boat "A" destroy all the electronics on boat "B" in the next slip?

It's Mother Nature's way of reminding us that she does not intend to follow our rules!

Do you recall that not long ago we tried to bribe Mother Nature into giving us a good harvest by throwing some poor Virgin into the volcano? That was state-of-the-art science at the time. We laugh at the idea now, (virgins must not be wasted) but the reality may be that our treasured explanations of her might be just as funny to our descendants.

Remind me; what was our explanation of the Sun back in the days of bustles and top hats?

Dave is right: if anything worked, the insurance companies would require it. More than that, if anything half way worked, someone, some time since the invention of sails would have discovered it and be at least a footnote in history. (OK, Ben Franklin was 'way cool, but he was primarily concerned with steeples and barns.)

The concept that something is "better that nothing at all" kept blood-letting at the top of the list of accepted medical cures for centuries.

Off topic: what caused the big bang?

Talbot
12th February 2013, 07:49 AM
......Do you recall that not long ago we tried to bribe Mother Nature into giving us a good harvest by throwing some poor Virgin into the volcano? That was state-of-the-art science at the time. We laugh at the idea now, .......

I believe that the virgins had to be fully adult (over 21) and this practice fell into the vaults of history more because of the lack of virgins than any fault with the concept

:tic)

Tropic Cat
12th February 2013, 11:22 AM
virgins? over 21?. Agreed, an extremely rare commodity which I don't believe is available in my country.

Gringo
12th February 2013, 11:27 AM
I'm going to blame it more on women's lib. I think there are PLENTY of ugly 21 year old virgins around.

But in the late 60's and early 70's, it got increasingly harder to keep flinging women into open pits of lava. They got organized and wouldn't stand for it any more. Threatened to use the vote etc. Then the ACLU got involved like there was something wrong with throwing ***ually inactive females into volcanoes. Then the EPA figured out the emissions and damage to the ozone layer caused by vaporizing virgins.....or was it Homeland Security?

Whichever ones are now presently trying to buy up all the ammunition that US manufacturers can produce .

ForumAdmin
12th February 2013, 02:12 PM
....or was it Homeland Security?
No, I distinctly remember it was the ETA as the main agency, the Homeland security did not exists then. The Noise Abatement Society were about to take action on the amount of screaming going on but the ETA beat them to it.

I just think its worth getting your facts straight because it would be wrong to distort history:)

Gringo
12th February 2013, 04:49 PM
Yeah, you're right. I just vaguely remember something about putting holes in the ozone layer. I didn't exactly remember the process. The late 60's were pretty fuzzy.

Tropic Cat
13th February 2013, 09:47 PM
....The late 60's were pretty fuzzy.


If you say you remember them vividly, you clearly weren't there.

Gringo
14th February 2013, 01:57 AM
Evidently I had a good time.

reports are still filtering in.

HappyEnding
14th February 2013, 01:20 PM
All you need is a flux capacitor wired to the mast and a Delorean mounted to the tramp, I think the new island packet cat has this option, and then you can time travel when struck by lightning! :thumb
Maybe go back somewhere where there actually "were" virgins?

Gringo
14th February 2013, 01:58 PM
All you need is a flux capacitor wired to the mast and a Delorean mounted to the tramp, I think the new island packet cat has this option, and then you can time travel when struck by lightning! :thumb
Maybe go back somewhere where there actually "were" virgins?


I might be tempted to go check out what's forward in time. Pretty scary thought, though. Do we think private ownership of self contained, mobile yachts will go on forever?

Or maybe the world will open up to complete freedom of travel for non polluting vehicles that use only wind or solar, giving sailors and those who soar aloft world citizenship.....

yeah, right.

The past it is.

But think of the profit in selling advanced technology to the primitives!!

Sandy Daugherty
14th February 2013, 04:25 PM
Faraday cages must NOT be grounded. That can make them part of the potential strike path or eddies. The whole concept of a Faraday Cage is to create a bubble of insulated space surrounded by an easier path for the accompanying EMI, not the strike. It should have rounded edges to avoid point foci's, but it can be an open mesh and still work.

Being part of the strike path is a guaranteed melt-down, but electronics, particularly IC chips are vulnerable to moderate EMI fields that would do no more than raise the hair on your arm. There is little to be accomplished by trying to divert the strike, but shielding the electronics from the worst of the EMI is do-able.

I have a large aluminum briefcase for my emergency electronics, as well as smaller, rounded stainless steel containers for individual units with a set of long shelf life alkaline and a set of rechargeable batteries. There is a good solar charger in the ditch bag. Every gadget uses the same size batteries.

georgetheleo
14th February 2013, 07:35 PM
Surely your joking Mr. Feynman?

Talbot
15th February 2013, 07:55 AM
All you need is a flux capacitor wired to the mast and a Delorean mounted to the tramp, I think the new island packet cat has this option, and then you can time travel when struck by lightning! :thumb


That is going to take some re-engine adjstment in order to achieve the necessary 80mph.

colemj
15th February 2013, 03:22 PM
There is little to be accomplished by trying to divert the strike

There is a lot to be accomplished by trying to guide the strike to ground. Not having the strike exit the boat by blowing holes through the hull comes to mind...

Mark

Sandy Daugherty
15th February 2013, 04:05 PM
Sorry Mark, I was referring to protecting electronics.

I suspect that lightning pursues the path of least resistance, that it can be thought of as having mass and inertia (a presumption from observing extremely high speed photography) and that there are a complex hierarchy of other components affecting its path.

To the best of my knowledge* no one has come up with a reliable remedy, and that especially includes those who have a vested interest.

* My PDQ 32 was struck by lightning, and I did a considerable amount of time researching the literature. I wanted to understand how the antenna cable was vaporized inside the mast, and every piece of electronics was fried except for a motherboard in an anti-static wrapper, but there was no discernible exit path anywhere on the hull.

I concluded that every theory or gadget put forward has been convincingly repudiated somewhere else. In short, that Mother Nature likes her privacy.

Tropic Cat
15th February 2013, 04:37 PM
Sandy, what did your DC circuit breakers look like after the event? Mine were covered in carbon as the high voltage generated by lightning in my boat wiring jumped all the breakers in the box.
As you know I lost everything electric / electronic connected to the boat but everything electronic running on internal batteries was unaffected.

I learned this hard lesson and no more expensive electronics for me.

ColdFusion
17th February 2013, 11:18 AM
To the best of my knowledge* no one has come up with a reliable remedy, and that especially includes those who have a vested interest.

...I concluded that every theory or gadget put forward has been convincingly repudiated somewhere else.
Precisely my thoughts.

Sandy Daugherty
21st February 2013, 02:58 PM
Sorry Rick, I don't remember what the panel looked like. I had great insurance that covered everything, and I ended up with all new electronics. I was later offered an early retirement, and sold the 32.

mikereed100
23rd February 2013, 11:50 PM
Here in SE Asia they sell faraday cages in many of the larger grocery stores. They cost about $5, come in many sizes and as a bonus come stuffed with fancy cookies.

BigCat
24th February 2013, 10:00 AM
Here in SE Asia they sell faraday cages in many of the larger grocery stores. They cost about $5, come in many sizes and as a bonus come stuffed with fancy cookies. Long ago I sailed to Fiji, where they sold huge tins of what they called 'ship's biscuits.' They were like American saltine crackers, but unsalted and very thick and heavy. You don't want your stuff to actually touch the Faraday cage, so put something insulating between your portable electronics and the 'cage.'

Sandy Daugherty
24th February 2013, 03:04 PM
I found some nice stainless steel containers with rounded edges, big enough to hold a handheld device and a bunch of alkaline batteries, which have a shelf life measured in years. My ditch bag also has a high output solar panel that charges AA and AAA batteries.

I have a couple of the containers left. I gave up trying to rust-proof tin cans and fruitcake pans.

They do need to be lined with antistatic foam.

Gringo
24th February 2013, 03:23 PM
It's such a frigging miracle to me that all those millions of sailors with countless boats traveled to every corner of this planet for thousands of years without a single AA cell, Faraday cage, or piece of stainless. Amazing. Is lightning a recent phenomena? A side effect of this past 100,000 years while we investigated campfires? I'm starting to doubt the stories. Magellan NEVER could have made that voyage without an AIS and radar. No way. And Balboa? Who are we kidding. Sailing all the way across the Atlantic and then crossing Central America without GPS, Active Captain or Explorer Charts? Never happen. I suspect he sat in a pub in Lisbon drinking absinthe and fabricating those logbooks.

dmmbruce
24th February 2013, 05:22 PM
Gringo, you have been over-dosing on reality!

Keep it up!

::)

Mike

BigCat
10th March 2013, 09:43 AM
I suspect he sat in a pub in Lisbon drinking absinthe and fabricating those logbooks.

Well, I sailed across the Pacific in the 70s, as well as taking a cruise from Newport CA, to Honolulu, to Seattle, to Newport Beach, CA. I had an Accutron watch that used a tuning fork to keep the time (you could hear it hum if you put your ear to it,) a Zenith Transoceanic shortwave / long wave radio that would bring in the GMT time (usually,) that also served as a crude radio direction finder along the US coast, a Tamaya ***tant, and a compass. Charts were made of paper, and you used a divider and a walking ruler with them. Later, we had a couple of cheap quartz watches, after they were introduced. Of course, we also had pilot books and charts.

If the sun didn't shine, we grew progressively more uncertain about our location. I remember at least one occasion when this was a source of concern, as we ran under bare poles from Whangerei in NZ, towards the forbidding and unlit cliffs of the Kermadecs. We decided to run after my wife woke me up and said, 'Tim, I was just standing on the side of the doghouse!" (We sat sideways on the dinette in the doghouse, when at our ease, back to port against the side of the doghouse, feet to starboard.)

As far as lightning went, I hoisted an aluminum tube on a spare halyard, to which I had attached, if I recall correctly, a 12 copper gauge wire that I hoisted aloft if I suspected lightning was nearby. The end of the wire was stripped and I led it over the side and let it trail in the water, perhaps 10' of bare wire. I know it worked, because I had it aloft near the equator, while sailing from Fiji to Tuvalu, and I heard a sizzling sound when I was down below. I went on deck and looked aloft. St. Elmo's fire was dancing from the top of the aluminum pole, which stuck above the main mast a bit, just like an old fashioned burgee pole. My masts were solid wood, grown fir sticks, and I had no standing rigging and none of the stuff associated with standing rigging.

No lighting struck my fiberglass monohull. The ballast was inside the fiberglass hull, so there wasn't a lot of metal contact in the water. I had no broadcasting radio, so no grounding plate. There was no bonding system. In those days, bonding systems weren't common, and advice concerning them was at best ambivalent, at least in the yachting community. The prop shaft was isolated from the engine by a flexible drive coupling, and there were a couple of under water through hulls - one for the engine cooling water, and one for the marine head intake water.

We drank no absinthe, but we did carry a moderate supply of beer, which we drank warm. By warm, I mean tropical seas warm, about 80 degrees F: Olympia beer in the E. Pacific, and Foster's larger in the West. I also recommend Hinano (Tahiti,) and Fiji bitters.

I usually kept in the shade, but somehow ended up with one melanoma decades later. It was caught early, so no big deal. Beware of multicolor moles that feel damp and slimy, and wear your waterproof SPF 50 at all times when sailing in the tropics.

Was it risky? Well, not so bad, if you were really, really careful. I do remember two boats disappearing at sea - both Wharram cats. Another single hander I knew slightly fell overboard. Amazingly, a friend in another yacht went looking for him, and found his friend's boat on Minerva Reef, minus the single hander. The logs showed that he had probably fallen overboard a couple of hundred miles before the boat hit the reef.

Another guy I knew left a boat alone for days on Pitcairn, in a completely unsheltered anchorage. It was gone when he came back looking for it. Another boat was wredked on Kandavu Island in Fiji, from the bad practice of leaving the boat sailing at night with no one on watch. I remember another tale by a delivery skipper about a delivery from Hawaii to Seattle on which the mishaps included a lost shroud and an oilcanning hull, that occurred after a bulkhead tore loose from the hull (in a fiberglass hull in which the bulkhead was stuctural.)

LifePart2
5th June 2013, 05:04 PM
Well, we finally built and installed our solution.

You can see the pics over on our blog http://lifepart2.info/equipment/lightning-protection-for-catamarans-one-boats-solution

Hopefully we will never find out if it works or not :)

eddi887
14th August 2013, 01:17 PM
Just and FYI...

I have a Witness 35 catamaran, designed by Lock Crowther. It has a sleeve through the structure below the mast. In the sleeve is a large coated copper cable bolted to the mast that extends a few inches under water. It stays there all the time and it seems stiff enough that you don't have to worry about it moving around and hitting the boat. I don't know whether or not it works, but from the looks of the setup, it was designed that way...

LifePart2
14th August 2013, 02:40 PM
So the tube extends down from the bottom of the bridgedeck (I am assuming the mast sits over the bridgedeck) straight down into the water?

Interesting. Any photos of that?

Noel