Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 18-11-2020, 15:04   #106
Registered User
 
StoneCrab's Avatar

Join Date: Jul 2019
Posts: 548
Images: 2
Re: Lightning Protection for Electronics

The smell of ozone, corona discharge on the shrouds and your hair standing up are all indications that your electronics are experiencing high voltages. If you haven't seen any lightening yet, it is sure to come.

On the upside, if you are streaming a corona, that is a plus since the charges are dissipating.

The downside is that if your hair is standing up, the radio is probably already fried.

These discussions are always interesting since there is a lot of electrical theory, some experience and lots of opinions. I've been in the situation described in the first paragraph. Headed to the closest harbor and escaped any real damage. There was a boat headed out when we were headed in. We warned them, but they went anyway. The Coast Guard towed them back in about 30 minutes later. The top of their mast was practically melted off. The boat had scorch marks everywhere and the diesel engine was disabled.

About a month later, a refinery that I was working in got hit on one of the tall distillation towers. The lightening traveled through the computer control circuits taking out the control system. It was interesting to pull the boards and witness the path taken by the burned board traces. There was nothing direct about the path. I called around the area and pulled together a team of engineers from several companies to discuss lightening protection. Each company had its own theories and methods. They all sound good and are backed by rational thinking and science.

I think where the theories and installations break down is that we don't really understand the physics in a million volt environment. Superheated air, instantaneous current flow, localized magnetic fields, and the breakdown of the very structure of the materials combine together in the shortest time period imaginable.

Is calling a lightening strike a DC event fair given its transitional nature? The theory is that current flow is only in one direction, so it isn't technically AC either. I think where things fall apart is when we come up with solutions based on our perspectives that may or may not be correct.... and likely correct for one lightening strike and not another. There is plenty of evidence that seemingly inconsistent localized conditions effect the lightening's behavior... like the short mast between two taller masts getting hit.

I don't think there is a definitive answer regarding protection or damage mitigation, but on the other hand, it can't hurt to try.
StoneCrab is offline   Reply With Quote
Old 18-11-2020, 16:28   #107
Registered User
 
capn_billl's Avatar

Join Date: Aug 2010
Location: Naples, FL
Boat: Leopard Catamaran
Posts: 2,572
Re: Lightning Protection for Electronics

Luck favors the well prepared.

You can find just as many anecdotes about people who died while wearing a bullet proof vest.

Armpit shots, head shots, neck shots all kill dozens who thought they were protected.

Yet thousands of soldiers, and police owe their lives to that body armor.

One in a thousand lightning strikes are what are called super strikes.

Coming from the upper atmosphere they carry several orders of magnitude more energy than the typical bottom of the cloud strike.

Because the typical roof can't withstand a hurricane, do we not bother with shingles that can only stop rain?

No. We prepare for what's likely, and just know nothing we are likely to do will withstand an extreme event.

If you only visit your boat sunny weekends, any lightning protection is likely a waste of money.

If you live on your boat having protection at least for a moderate strike is wise.

Ground the highest point, have a heavy conductor to an electrode in the water. Disconnect electronics.

That will take care of 90%.
capn_billl is offline   Reply With Quote
Old 19-11-2020, 18:10   #108
Registered User
 
Dave_S's Avatar

Join Date: Jun 2016
Location: Brisbane Australia
Boat: Schionning Waterline 1480
Posts: 1,987
Re: Lightning Protection for Electronics

Quote:
Originally Posted by StoneCrab View Post
The smell of ozone, corona discharge on the shrouds and your hair standing up are all indications that your electronics are experiencing high voltages. If you haven't seen any lightening yet, it is sure to come.

On the upside, if you are streaming a corona, that is a plus since the charges are dissipating.

The downside is that if your hair is standing up, the radio is probably already fried.

These discussions are always interesting since there is a lot of electrical theory, some experience and lots of opinions. I've been in the situation described in the first paragraph. Headed to the closest harbor and escaped any real damage. There was a boat headed out when we were headed in. We warned them, but they went anyway. The Coast Guard towed them back in about 30 minutes later. The top of their mast was practically melted off. The boat had scorch marks everywhere and the diesel engine was disabled.

About a month later, a refinery that I was working in got hit on one of the tall distillation towers. The lightening traveled through the computer control circuits taking out the control system. It was interesting to pull the boards and witness the path taken by the burned board traces. There was nothing direct about the path. I called around the area and pulled together a team of engineers from several companies to discuss lightening protection. Each company had its own theories and methods. They all sound good and are backed by rational thinking and science.

I think where the theories and installations break down is that we don't really understand the physics in a million volt environment. Superheated air, instantaneous current flow, localized magnetic fields, and the breakdown of the very structure of the materials combine together in the shortest time period imaginable.

Is calling a lightening strike a DC event fair given its transitional nature? The theory is that current flow is only in one direction, so it isn't technically AC either. I think where things fall apart is when we come up with solutions based on our perspectives that may or may not be correct.... and likely correct for one lightening strike and not another. There is plenty of evidence that seemingly inconsistent localized conditions effect the lightening's behavior... like the short mast between two taller masts getting hit.

I don't think there is a definitive answer regarding protection or damage mitigation, but on the other hand, it can't hurt to try.

If I feel the hair stand up on the back of my neck do I have time to run around and switch off the 3 main isolator switches or am I putting myself at an unreasonable risk.

Bonus question, if I have a Fariday Cage, isolated from everything, can I touch it straight after a strike or does it hold some capacitance?
__________________
Regards
Dave
Dave_S is offline   Reply With Quote
Old 19-11-2020, 18:26   #109
Registered User

Join Date: Mar 2014
Location: Seattle, WA
Posts: 831
Re: Lightning Protection for Electronics

I was in a design meeting today to install an outdoor pole with WiFi antennas. Talk came up about whether to add lightning protection. The NASA engineers admitted that it’s all still a big crapshoot. But you do it anyway hoping to dissipate energy and to improve your odds. No guarantees though.
mako is offline   Reply With Quote
Old 19-11-2020, 18:36   #110
Registered User

Join Date: Feb 2006
Posts: 2,767
Re: Lightning Protection for Electronics

Quote:
Originally Posted by Sailing Ohm View Post
Still a crap shoot in my experience. I’ve know of boats with all the bells and whistles in lightning protection have their systems fried (the boat ultimately sank) and I’ve known boats that did nothing who have no damage except a fried vhf antenna.
Other than ensuring your properly grounded and a path of least resistance is created before your sensitive electronics I think the only thing you can really do is ensure you don’t rely entirely on your electronics to get to a safe harbor.

It sounds like one more stipulation insurance companies are trying to use to get from paying out claims.
I think if Thor decides he’s going to damage your boat there’s not much to be done about it.
Tell us all the Harbors in Florida that are "safe" from lightning please
geoleo is offline   Reply With Quote
Old 19-11-2020, 18:42   #111
Registered User

Join Date: Feb 2006
Posts: 2,767
Re: Lightning Protection for Electronics

I have a new to me Beneteau 41s5 . It has rod rigging and a aluminum mast stepped on deck with a 5"dia ss compression post on the iron keel. I am going to bond the cap shroud chainplates on each side to the iron keel bolts. Im in Tampa Florida sometimes called the lightning capital. Comments?
geoleo is offline   Reply With Quote
Old 19-11-2020, 22:40   #112
Registered User

Join Date: Jan 2014
Location: Coffs Harbour, NSW
Boat: FreeFlow 50 cat
Posts: 1,336
Re: Lightning Protection for Electronics

Quote:
Originally Posted by geoleo View Post
I have a new to me Beneteau 41s5 . It has rod rigging and a aluminum mast stepped on deck with a 5"dia ss compression post on the iron keel. I am going to bond the cap shroud chainplates on each side to the iron keel bolts. Im in Tampa Florida sometimes called the lightning capital. Comments?
Does the mast base plate connect to the compression post plate with bolts?

The issue is the lightning is trying to get to the water surface by the shortest distance, period. Whereas you seem to be trying to "persuade" it to go to your keelbolts underwater, via some wire from your chainplates.

The dangerous aspect is if the bolt heads down the mast, into the compression post, but then jumps in a sideflash to the waterline from inside the boat. If you are between the bolt and the exit point to the sea surface, bad news
BigBeakie is offline   Reply With Quote
Old 20-11-2020, 15:04   #113
Registered User
 
Dave_S's Avatar

Join Date: Jun 2016
Location: Brisbane Australia
Boat: Schionning Waterline 1480
Posts: 1,987
Re: Lightning Protection for Electronics

Seems hard to predict where it might go.
Attached Thumbnails
Click image for larger version

Name:	Screenshot_2020-11-21-08-44-50-747.jpeg
Views:	47
Size:	242.1 KB
ID:	227315  
__________________
Regards
Dave
Dave_S is offline   Reply With Quote
Old 20-11-2020, 15:45   #114
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,084
Images: 241
Re: Lightning Protection for Electronics

Quote:
Originally Posted by Dave_S View Post
If I feel the hair stand up on the back of my neck do I have time to run around and switch off the 3 main isolator switches or am I putting myself at an unreasonable risk.
Bonus question, if I have a Fariday Cage, isolated from everything, can I touch it straight after a strike or does it hold some capacitance?
1. Maybe, but probably not.
If your hair stands on end, during a thunder storm*, lightning is about to strike you.
If that happens, the best advice is to seek shelter immediately. If that's not possible, squat low to the ground on the balls of your feet, making yourself the smallest target possible and minimize contact with the ground.
* Actually, lightning is not confined to thunderstorms. It's been seen in volcanic eruptions,extremely intense forest fires, surface nuclear detonations, heavy snowstorms,and in large hurricanes.

2. Yes. It holds no charge.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is online now   Reply With Quote
Old 20-11-2020, 19:53   #115
Registered User

Join Date: Oct 2018
Location: Dallas, TX
Posts: 564
Re: Lightning Protection for Electronics

Quote:
Originally Posted by Dave_S View Post
Bonus question, if I have a Fariday Cage, isolated from everything, can I touch it straight after a strike or does it hold some capacitance?
An ungrounded Faraday cage will store a charge just like any other ungrounded metallic object will. However, it will be in the static electric shock range, not the stop your heart range.

An ungrounded Faraday cage will protect you and your contents from electromagnetic radiation (depending on the size of the mesh) but you absolutely shouldn't touch it during a strike.

Gas powered service vehicles, which behave like a Faraday cage, routinely have grounding chains to prevent the buildup of static charges. If you park a service truck without grounding chains under a 230kV+ transmission line in dry weather and let it sit a while you'll be in for a nice static shock when you touch the metal door handle.
NPCampbell is offline   Reply With Quote
Old 21-11-2020, 05:31   #116
Registered User

Join Date: Nov 2020
Posts: 92
Re: Lightning Protection for Electronics

Watching a youtube video this AM...Sailing Yacht Florence....noticed their antenna array mounted on their transom arch.
Made me think of this topic.

Made me think about the idea of getting as much as reasonably possible off the high mast. I wonder if odds get a tiny bit better in the event of a strike, that maybe some of the electronics might get spared.
Based on my one experience I think not, the way the lightning seemed to net through the entire boat....but maybe sometimes.

Would it be worth loosing a bit of height?
skyhawk is offline   Reply With Quote
Old 21-11-2020, 06:33   #117
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 995
Re: Lightning Protection for Electronics

If you could get the entire mast/ mast head free of electrical, then I think you would improve your odds (assuming a proper grounded mast). Talking about electronics damage nothing to do with strike probability. But it is not just the VHF, typically also anchor light, wind sensor, TV antenna, steaming light, and radar. Any of those devices are a potential path into the ships electrical system. And all them little wires (NMEA 2000 and on and on) are little antennas just waiting to collect their bit of induced energy.


In a typical building lightning protection, the air terminals and down conductors all are located along the roof and down the outsides. Don't typically clamp your TV mast to the lightning air terminal.


Frankly
Frankly is offline   Reply With Quote
Old 21-11-2020, 07:23   #118
Registered User

Join Date: Oct 2007
Posts: 387
Re: Lightning Protection for Electronics

I commented earlier on this topic, saying I was delivering a friend's 45ft catamaran from Bahamas to New York and we were struck twice on two different days. It was equipped with a Forespar lightning 'brush' at the top of the mast and the two shrouds each had separate underwater grounding plates.

The first strike was more of a sheet lightning strike and burned some things, but we were able to get some electronics going again and some things worked.
The strike the following night was much more severe. Broad blue bands of huge proportions came straight down (up?) in the sea all around us. I had never seen such a display before. The air was full of lightning ozone odor and the sea had a sheen of smoke/steam? on the surface. The flashes were near constant and lit up the sky (about 3am). I was off watch (there were five of us onboard) but in the cockpit. We were hand steering because of the previous strike knocked out the autopilot and we were about 200miles offshore.
I could feel the concussion of the strike, like an explosion, that nearly took my breath away. I temporarily lost hearing and my hearing was not fully regained for several days. The masthead wind, VHF, light, Windex melted and molten plastic and metal rained down on deck. The deck lights on the spreaders exploded and shattered glass rained down on the deck.

Though the shrouds were grounded, the main strike came down the mast, that was not grounded. The charge leapt through the deck mast base bolts to the inverter and battery banks mounted directly below it at the salon settee. The batteries exploded and the inverter was a mass of melted plastic and metal. The electrical control panel was burned and melted and the whole of the electrical system was dead. The charge then travelled through the battery connection wires to the engine it was grounded to and killed the engine electronics and warped the connection plate between the engine and transmission putting it out of service.
I immediately went below decks to see if there were any leaks, lifting floorboards and checking on the sleeping off watch crew. No leaks and no damage to the hull or rig integrity.
It is not just the electric charge finding a path, there is a lot of colateral damage.
Paul Howard is offline   Reply With Quote
Old 22-11-2020, 16:32   #119
Registered User

Join Date: Jan 2014
Location: Coffs Harbour, NSW
Boat: FreeFlow 50 cat
Posts: 1,336
Re: Lightning Protection for Electronics

"Though the shrouds were grounded, the main strike came down the mast, that was not grounded. The charge leapt through the deck mast base bolts to the inverter and battery banks mounted directly below it at the salon settee. The batteries exploded and the inverter was a mass of melted plastic and metal."

Wow! That must have been fairly traumatic for those onboard, but very lucky there was not anyone sitting on the settee at that fateful moment.

We must remember that although this thread is about protecting electronics from lightning strike, it is the first priority to protect the lives aboard that are
the focus of lightning mitigation systems.

This means creating as effective a conductor as possible from mast to water, and ideally for catamarans directly below the mast. For cats, there will be either a structural bulkhead or a mast compression post below the mast step, giving possibilities to run the necessary conductor that can be lowered to the water surface.

For monos, or trimarans, the conductors should provide a path from the mast base to the waters surface, ie along the sides of the hull at the waterline, in order to avoid a sideflash event that can strike someone inside the boat. These waterline conductors also provide the charge balancing function in the moments before a strike, as detailed on Dr. Thomson's site.
BigBeakie is offline   Reply With Quote
Old 22-11-2020, 16:36   #120
Marine Service Provider

Join Date: Jun 2015
Location: Croatia
Boat: Elan 45 impression
Posts: 1,128
Re: Lightning Protection for Electronics

Quote:
Originally Posted by stull61 View Post
I am currently looking at protecting my new FP Saba 50 Catamaran from lightning as much as I practically can.
best Lightning Protection is good insurance boat
more is offline   Reply With Quote
Reply

Tags
electronics, lightning, rot

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lightning protection for a catamaran Crak Multihull Sailboats 51 23-07-2021 01:17
Built-in Lightning Protection for Electronics stillbuilding Marine Electronics 8 23-02-2010 00:42
Lightning Protection JusDreaming Health, Safety & Related Gear 57 03-10-2007 10:25
NFPA 780 Lightning Protection Systems GordMay The Library 0 16-01-2006 03:53
Lightning Protection Stede Electrical: Batteries, Generators & Solar 5 20-11-2003 17:27

Advertise Here


All times are GMT -7. The time now is 03:14.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.