Lightening strikes

[dog man]

any good method to hepl lessen the damage? thx

 

[Pascal]

post moved from under counter refrigeration thread... when starting a new thread, pls do not reply to an irrelevant existing thread.


whenever there is a serious risk of lightning strike, I always lower all antennas... not 100% it really helps or if it's just a feel good precaution. I also try to anchor not too far for sailboats...

Ideally you want to have a heavy copper wire running from an antenna down to a heavy duty grounding plate under water. i've often wonder if having a removable plate that you could just dump overboard attached with copper running down an antenna woudl work better at keeping the energy outisde the boat. obviously, it woudl only work anchored and when you're aboard.

 

[eze2bme]

Have a sailboat with 60 foot mast berthed next to your slip!

 

[REBrueckner]

"i've often wonder if having a removable plate that you could just dump overboard attached with copper running down an antenna woudl work better at keeping the energy outisde the boat."

It most certainly does help, but is never a guarantee. I installed a stud and wing nut connection on my aluminum radar arch and if a bad situation arises, I remove my guppy style cable from electrolysis duty and attach it to the arch....

and lowering antennas also helps, but nothing guarantees safety from lightning....

Shutting off all electrical accessories especially genny's can help a bit...storing electronics inside grounded even ungrounded metal boxes (faraday cages) might also help prevent damage.

While we are on the subject: Anybody know if Hatt grounds stainless handrails???

 

[Trojan]

Your better off not grounding anything. Lightning follows the best route. Creating a path directly to ground says hit me. And if there are any turns in the ground path above you it won't turn, It goes right straight to ground. I ground nothing for lightning. Why does the golfer get hit, or the tree. It goes to the best direct path to ground. Why be a lightning rod and create a near perfect route to ground. A sailboat does not have much choice. Even a radar arch left ungrounded is better than grounded. The lightning WILL go to the best path to ground. Even through you. Why set yourself up as a target. The engines make a good ground don't get between them.
BILL

 

[bobk]

Have a sailboat with 60 foot mast berthed next to your slip!

A friend had much of his electronics fried when the SB next to him took a direct hit in the slip. I have four around me and I'm not so sure I feel better in a storm.

Bob

 

[DCMY #92]

I used to think lowering the antennas was the thing to do, but now I'm not so sure. On two occasions when a heavy Tstorm was nearby I could hear my antennas sizzling like frying bacon. My first thought was that I'm not about to touch them and get fried while in the process of lowering them. Fortunately - I got no strike.

If I have it right, I understand that the purpose of a lightning rod is not to attract lightning, but rather to protect (hopefully) the structure it's mounted on from receiving a strike. It does so by bleeding off the static charge in the structure that attracts the lightning in the first place. I am now of the opinion (maybe wrongly) that leaving the antennas up allows them to bleed off the boat's static charge.

 

[SportFishCruising]

I had wondered about this as well and have found the following two articles very informative:

(1) From the University of Florida:
http://www.nasdonline.org/docs/d000001-d000100/d000007/d000007.html

(2) TE-4 — Lightning Protection Standards by American Boat and Yacht Council:
This technical information report is intended as a guide for the design, construction, and installation of lightning protection systems on boats. Its primary objective is to decrease the risk to personnel and the risk of fire and sinking. Additional measures may be needed to harden electrical and electronics systems against lightning damage.
The probability of a lightning strike varies with geographic location and the time of the year. When the conditions that create an electrical charge between clouds and the earth exist, there is nothing that can be done to prevent the lightning discharge. A boat can be struck in open water or while tied to the dock.
This technical information report applies to powerboats and sailboats if a lightning protection system is installed. Complete protection from equipment damage or personal injury is not implied.
A lightning protection system offers no protection when the boat is out of the water, and is not intended to afford protection if any part of the boat comes in contact with power lines while afloat or ashore.
Protection of persons and small craft from lightning is depended on a combination of design and maintenance of equipment. The basic guides contained in this technical information report should be considered and used in designing and installing a lightning protection system. However, in view of a wide variation in structural design of boats, and the unpredictable nature of lightning, specific recommendations cannot be made to cover all cases.
http://www.abycinc.org/standards/purpose.cfm#TE4

Also a rather extensive discussion on same subject found here:
http://www.livingaboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=000871#000000

 

[Trojan]

If you would like to try and protect your radio's. Disconnect the antenna from the back of the radio and let it hang. If the antenna should take a hit and most times it is not a direct hit. There is no way the antenna will attract a direct hit unless it is a plain wire or a SS whip. Static build up on a fiberglass antenna does not happen. The biggest lightning attraction on the boat are the engines. Just the static discharge in the air nearby is enough to fry your radio and antenna if left hooked up. The wire size of your radio antenna is so small inside your antenna shell, that the smallest radio frequency static lightning discharge can vaporize the wire and blow apart the thin brittle outer shell. The antenna it self is NOT grounded, only the coax feed outer shield is. Remember that you standing on the bridge out in the open soaking wet makes YOU an attraction. When lightning hits it is not a small little spark it encompasses a large area of charged particles. The lightning rod tries to direct the charge, but the charge is so large it can not be completely be directed. You can only hope that you never take a direct hit. Your best defence is don't give the lightning bolt an attraction. When I'm on watch for the weather department. I have 6 antenna on my van. Every thing is up from ground. Nothing is grounded other than through the tires which semi ground the van.
BILL.

 

[DeeRow]

Last summer I worked on two boat that had lightening strikes: one on a lift, one on blocks in the boat yard. The insurance adjuster said that most lightening strikes occur on boat that are out of the water. Not sure what this means in the context of this discussion. Perhaps boats that are grounded (in the water?) bleed off the static charge better than boat not grounded?

Mark

 

[saltshaker]

Last summer I worked on two boat that had lightening strikes: one on a lift, one on blocks in the boat yard. The insurance adjuster said that most lightening strikes occur on boat that are out of the water. Not sure what this means in the context of this discussion. Perhaps boats that are grounded (in the water?) bleed off the static charge better than boat not grounded?

Mark

Maybe due to the fact that the boats on land sit higher than the ones in the water. My boat stands almost 10ft taller when blocked plus the added height above water level. All this sitting in an open area with nothing taller nearby.

 

[seacolt]

I had Lightening hit my boat years back. Was A 33 Egg Harbor at the time. We were coming into port in a severe lightening storm. I was very uneasy with the situation, but we made it to our mooring and got off the boat ok. The next morning I tried to start the boat, Both engines were dead. I started to investigate and noticed my antenna was stolen (so I thought). Lightening hit caused lots of damage. My antenna had completely disintagrated except for the small metal stub and there was a perfect burn hole in my mic, Glad I wasn't talking on the radio at the time. Blew out all of my electronics and both distributors on the engines. Hate to think what would of happened if we were on the boat at the time. I take Lightening seriously and avoid it whenever possible. Just recently we had A fatality in our area, Guy was in A aluminum boat on a pond and got hit.

 

[REBrueckner]

"Your better off not grounding anything."
"The biggest lightning attraction on the boat are the engines."
"There is no way the antenna will attract a direct hit unless it is a plain wire or a SS whip."

All wrong wrong WRONG.

Read any science/reasearch on lightning including "leaders" and "static build up". Ask any surveyor. Read ABYC recommendations...do anything but follow the above advice.

I have previously posted in this forum the best grounding solutions.

Try reading this article for some FACTS:

http://en.wikipedia.org/wiki/Lightning_protection_system

The National Fire Protection Agency provides a risk assessment worksheet in their lightning protection standard...

Did anyone see recent the lightning strikes at the space shuttle launch tower??

University of Flordia used to have a good website article discussing their research. A quick check now shows a huge program in conjunction with the Army National Guard and Flordia Institute of Technology....I could not find the summary article.

Here is a site with many Lightning Protection" references:
http://www.lightning.ece.ufl.edu/

Power companies and communications companies DO provide lightning ground protection for their above ground equipment, antennas,buildings, as well as underground fuel storage tanks and underground buried cable lines.

 

[seacolt]

Read any science/reasearch on lightning including "leaders" and "static build up". Ask any surveyor. Read ABYC recommendations...do anything but follow the above advice.


Not sure if that was refered to my reply, but I was not giving any advice. I did not see the lightening hit my boat so i'm not sure what actually got hit. But everything I stated was true. Antenna was fiberglass not a whip or SS and yes it was completly gone nothing left but the metal stub at the bottom and it burnt A hole in the center of my mic.
I'm not as well versed in lightening strikes as you Rob but just stating the facts on lightening strike that happened to my boat.
Hope I did not confuse the issue. Next time I will leave it to the experts.

Wayne

 

[DCMY #92]

Rob,

I took a quick look at the references you suggest. They appear quite comprehensive, but it will take a while for me to find time to read them and properly digest all the information. In the mean time, can you give us a summary of what an effective lightning protection system for a typical Hatteras might look like? Our Hat is on the hard for an extended refit for another several weeks. Since we are in the lightning hot zone in Florida, I would not mind at all including improved lightning protection in the refit scope.

 

[Trojan]

"Your better off not grounding anything."
"The biggest lightning attraction on the boat are the engines."
"There is no way the antenna will attract a direct hit unless it is a plain wire or a SS whip."

All wrong wrong WRONG.

Read any science/reasearch on lightning including "leaders" and "static build up". Ask any surveyor. Read ABYC recommendations...do anything but follow the above advice.

I have previously posted in this forum the best grounding solutions.

Try reading this article for some FACTS:

http://en.wikipedia.org/wiki/Lightning_protection_system

The National Fire Protection Agency provides a risk assessment worksheet in their lightning protection standard...

Did anyone see recent the lightning strikes at the space shuttle launch tower??

University of Flordia used to have a good website article discussing their research. A quick check now shows a huge program in conjunction with the Army National Guard and Flordia Institute of Technology....I could not find the summary article.

Here is a site with many Lightning Protection" references:
http://www.lightning.ece.ufl.edu/

Power companies and communications companies DO provide lightning ground protection for their above ground equipment, antennas,buildings, as well as underground fuel storage tanks and underground buried cable lines.

If I had a 200ft tower standing in the air, I to would ground it along with the shuttle tower. But we are not a shuttle tower or any other type tall building. ReBrueckner your probably one of the people that stand under trees or hold up a metal shafted golf umbrella in storms. The main idea is don't make yourself or your boat a lightning rod. Your not the utilities company or anything like a shuttle tower. You can't direct a direct hit... Why don't you stand on your bridge a hold a grounded lightning rod and see where the lightning goes. Lets deal with our problems not the local radio stations 300ft towers or go ask one the storm spotters in the forest towers. Do as you like, but I will never make myself or my boat a lightning rod. Let it find its own ground someplace else. ReBrueckner why don't you post your preferred method of grounding again. Did you ever look at the wire size inside your antennas. Did you ever put an ohm meter across your antenna connection. I have seven 70ft towers and 20 some coax cables entering my home. NONE ARE GROUNDED. In the 20+ years I have lived here some of my trees have been hit. But not once have I ever had lightning enter my home from my towers or coax. Fourteen times I had lightning enter ny home through the phone line in two weeks. So much for the Utilities grounding. Do as you see fit. I still live by the rule DON"T MAKE YOURSELF A LIGHTNING GROUND ROD. There is no proof that lightning will follow any part of your lightning protection system. It does what it wants. If you want to try to direct the lightning. Cantilever an insulated pole way off the side of your boat at its highest point. Then suspend a 1/2 inch dia. cable from it into the water. Add a few loose 6 inch long wires on top of the cable like a whisk broom and your all set. Then pray it likes the cable more than the boat. I don't say My ideas are flaw less. I'm just telling you what I have done to protect myself, my home, my barns and hanger, my boat, my cars, and thousands of dollars in electronic. By all means do as you like. I just gave you 50 years of practical experience that seems to work. What do the mega yachts do. Why didn't Hatteras incorporate a lightning ground system in there boats if it worked. They did everything else. I know of no one that has a lightning ground system on there boat. Besides the blow boys. There is no way that you cannot sustain major damage from a direct strike.

BILL

 

[Maynard Rupp]

We definetly have two opposite opinions here. For all of our good we do need to get this straight. Either we should try toground the boat to nthe water, or we should do our best to keep it disconnected. I do know that lightning never seeks out an airplane and I was told that bthe fact that an airplane isn't grounded is why lightning is never a concern.

Now static electricity buildup and discharge is a whole different subject. Many think they were struck by lightning several times in a short period of time. No one is that unlucky folks. What you were seeing was static buildup and discharge. Modern racing sailboats with carbon fibre masts and hulls have static problems all the time. That carbon fibre is a semi-conductor and can hold some electricity to a point. When it leaves, you would swear you had a lightning strike. The space shuttle folks had to work on this a lot because those ceramic tiles that they use to control re-entry heat are a natural for holding electricity. This is what a ceramic capacitor does.

 

[REBrueckner]

DCMY posts: " can you give us a summary of what an effective lightning protection system for a typical Hatteras might look like?"

I no longer have up to date ABYC recommendations nor could I find my previous posts here. Someone could summarize the ABYC recommendations and post them here??.


PURPOSE
A lightning protection system does two things but guarantees NOTHING: it helps minimize static charge build up which often precedes a lightning strike, and if lightning does strike, it may help divert the strike to ground and reduce/minimize/eliminate damage.

ABYC STYLE MARINE LIGHTNING GROUND SYSTEM
The basic idea is to keep lightning ground connections aboard separate from the rest of the bonding and grounding (both dc and ac) system aboard. That means installing a separate ground plate outside the hull underwater and connected a smoothly routed heavy gauge cable to a lightning rod at a high point on the boat. Of great importance is that the cable be separate from other electrical wiring and conduits (separate routing) and smoothly routed...no sharp turns. ABYC used to recommended at least one square foot of conductor (say copper) for underwater...some serrations on the edges seems to facilitate dissipation. I forget the minimum size cable now ABYC recommends...maybe #4 AWG???....it was increased some years ago..it's in my old post somewhere.

Ask any marine insurance company that has been in business a while : "Why do boats that have been hit by lightning sometimes SINK?" Because things like thru hulls are bonded together with lightning grounding and lighnting is sometimes directed to them...they literally explode. Electronic controls of all types also can get blasted.

EASY AND SUPERIOR LIGHTNING PROTECTION
An alternative that I used on my 48 YF: I installed a lightning rod on my aluminum radar arch (up high) and a stud with a wing nut at one foot near the roof level. When lightning threatens I connect my "guppy" cable to that and hang the cable overboard OUTSIDE my hull.....that helps discharge static build up which helps prevent leader formation (a pre cursor to lightning strikes) and if hit helps direct the strike outside the boat. Keep the cable and weight shallow enough that it cannot foul your props if maneuvering is required.


I have been in Maine or Nantucket summers the last ten years and was hardly even in a lightning during that time, (an unexpected benefit of northern cruising) so I was not concerned; lightning and thunderstorms are much less frequent than my home port in NY (Long Island Sound). Last week in New Rochelle while my former HATT was hauled and on the hard three nearby boats in their slips (in the water) were struck in a single storm..maybe from a single strike...so I suggested to the new owner he hang another heavy cable from the radar arch into the water full time (and weight the underwater end with maybe five or six feet of chain or a ship size zinc).

Nothing guarantees protection, but keeping the lightning ground cable OUTSIDE the boat seemed to me an unamibiguous way to give your boat the best chance of avoiding damage.

And another item I have also previously posted: If you are EVER standing outside watching a "distant" thunderstorm and feel static charge building on your own body, go below IMMEDIATELY. This is morely likely aboard a fiberglass (insulated boat) than standing on ground, but can occur anywhere. That's the POTENTIAL beginning of a leader forming...charged ions forming...a precursor to a strike. I recently read in a scientific forum article that if you can SEE lightning, say on the horizon, you are already a potential (not necessarily likely) target.

 

[GaryNW]

My .02. Calder has pretty good coverage on the subject and he begins by acknowledging the intense debate that exists in academia and the internet. He also points out that there is broad agreement on certain principles-such as the importance of grounding.
On airplanes, since this was my career (boeing widebodies), I assure you lightning protection is extensive. I believe the average is 2 strikes a year for a typical commercial airliner. In most cases, passengers are unaware that a strike occured. The basic aluminum airframe, even the wings full of fuel, is the good conductor that you want. The electrical energy is not going to arc thru the passenger cabin when it has a good path around the circumference of the tube. Extensive use of composites complicates things. Virtually all exterior composite panels receive a static discharge coating as part of the paint scheme. Many panels, such as nacelles, a/c bay fairings, landing gear doors also have an aluminum foil covering on the inside surface. Many large grounding straps are then led to aluminum structure. With all engines now FADEC, the nacelle panels are really, really well bonded. You must be able to withstand a direct hit on the engine/ nacelle without frying a single transistor.
The 787 will be quite a challenge since the wings and fuselage are plastic. But hey, there are a lot of composite military a/p's out there.
Gary

 

[REBrueckner]

Gary posts: "The basic aluminum airframe, even the wings full of fuel, is the good conductor that you want."

That's the same reason you are quite safe from lightning in a traditional metal automobile. And why metal "cages" (enclosures) are recommended for protection of electronic equipment. And why in a fiberglass (poor conducting boat) things ought to be grounded to help drain lightning to ground as quickly as possible. But the fiberglass is still a better conductor than air so having crew stay inside is always a wise precaution when lightning threatens.

And thanks for mentioning Calder...an excellent source I forgot.

He says "..a poorly grounded mast merely offers a greater probability that the strike will be a powerful one since the electrons will not have been bled off by a functioning lightning rod...Damage will be greater...."

My 1996 edition does not discuss a separate ground plate for lightning ground, does mention the prior (outdated) #6 AWG cable receomendation which IS upgraded to #4 AWG, but does note lightning wiring with six feet of the boats electrical wiring may caused lightning to "jump" and cause damage.

Fuss with Mother Nature at your own peril!!!