Cruisers Forum
 


Join CruisersForum Today

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 13-01-2019, 14:09   #16
Registered User
 
nwdiver's Avatar

Join Date: Aug 2011
Location: Vancouver, BC
Boat: C&C Landfall 38
Posts: 469
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by AedanC View Post
I’m very interested in that aspect, do you have any photos of the faraday cage?
It's a soldered 1/8 inch copper box with an inset lid, on the inside is aluminum diamond mesh then a 3/4 inch closed cell foam....if a microwave works it will work better....
__________________

nwdiver is offline   Reply With Quote
Old 13-01-2019, 14:15   #17
Senior Cruiser
 
Dave_S's Avatar

Cruisers Forum Supporter

Join Date: Jun 2016
Location: Brisbane Australia
Boat: Schionning Waterline 1480
Posts: 987
Re: Lighting strike on an all electric boat????

I was given advice to drop the anchor into the water if lightning was around. I was thinking with the anchor locker at the base of the mast it would be a simple job to connect the mast to the chain guide and create a connection. Could also create a connection to the front stay.

Any thoughts ?
__________________

__________________
Regards
Dave
Dave_S is offline   Reply With Quote
Old 13-01-2019, 15:15   #18
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Boat: FreeFlow 50 cat
Posts: 1,008
Re: Lighting strike on an all electric boat????

Chain is not a good conductor because there is not enough contact surface between the links.

Lightning is "trying" to get to the surface of the water, not down into the water. So having several conductors at or very near the waterline are required, with correctly sized conductor wire between them and the mastbase.

See excellent information at www.marinelightning.com



Sent from my iPad using Cruisers Sailing Forum
BigBeakie is offline   Reply With Quote
Old 13-01-2019, 15:29   #19
Marine Service Provider
 
boatpoker's Avatar

Join Date: Nov 2008
Location: Toronto, Ontario or Bahamas
Boat: Benford 38 Fantail Cruiser
Posts: 3,516
Re: Lighting strike on an all electric boat????

I'm no expert but I have taken a couple of courses and handled a number of lightning damage claims on boats without and with various types of lightning protections systems.

My conclusion is that up to 200,000amps moving on the return flash at about 1/3 the speed of light does not care about any of your protection systems or devices. All such systems are built on "theory" with no substantial proof behind them. Research on strikes on water is very thin, research on fresh water strikes is almost non-existent.
__________________
That hysterical laughter you hear as you sail a way in your "new" boat ..... is the seller.
boatpoker is offline   Reply With Quote
Old 13-01-2019, 16:14   #20
Registered User

Join Date: Dec 2009
Location: Australia
Boat: building Roberts Mauritius 43ft
Posts: 736
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by boatpoker View Post
My conclusion is that up to 200,000amps moving on the return flash at about 1/3 the speed of light does not care about any of your protection systems or devices. All such systems are built on "theory" with no substantial proof behind them. Research on strikes on water is very thin, research on fresh water strikes is almost non-existent.

I understand where you are coming from. Even the "experts" don't fully understand lightning - why lightning is attracted to sharp/pointy edges and (for example) why most hull damage occurs at or near the water line.

But statistics can be a guide : the risk of a lightning strike at a particular place in the world, 90% of strikes are on high objects.........

"A system designed in compliance with a standard does not guarantee 100% immunity from damage. Lightning protection is an issue of statistical probabilities and risk management. Lightning protection systems designed in compliance with standard should statistically reduce the risk below a pre-determined threshold."(Marten Havelka)

I have lightning protection as anything that improves my chances is a plus. (My TV aerial has been hit and my neighbor's lobster boat has been hit)

Clive
coopec43 is offline   Reply With Quote
Old 13-01-2019, 17:09   #21
Registered User

Join Date: Oct 2014
Posts: 524
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by nwdiver View Post
I was also thinking of synthetic rigging.....this would make my mast the only way to the water
Subject of a previous thread.

Synthetic Rigging and Electrons
Montanan is offline   Reply With Quote
Old 13-01-2019, 21:49   #22
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Location: Bellingham
Boat: Outbound 44
Posts: 6,548
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by BigBeakie View Post
Chain is not a good conductor because there is not enough contact surface between the links.

Lightning is "trying" to get to the surface of the water, not down into the water. So having several conductors at or very near the waterline are required, with correctly sized conductor wire between them and the mastbase.

See excellent information at Marine Lightning Protection Inc.



Sent from my iPad using Cruisers Sailing Forum
Chain may not be a great conductor, when it comes to lightning it will conduct a lot of energy. A friend's boat was hit while at anchor near us in Costa Rica. He had a shiny, polished stainless steel bruce anchor. When he hauled the anchor one side was nice and shiny. The other side was heated metal rainbow colored along the whole side.

They were off the boat when the hit occurred. They went onboard and at first couldn't figure out why the floor boards were scattered in the cabin and on the settee. Thought is the bilge water boiled and blew the floor boards out.
Paul L is offline   Reply With Quote
Old 13-01-2019, 21:52   #23
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Location: Bellingham
Boat: Outbound 44
Posts: 6,548
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by Paul Howard View Post
I know from personal experience that lightning strikes when far at sea kills everything. Batteries burst, inverter and circuit breaker panel nothing but melted wiring. LED lighting burns out, even bilge pumps had to be replaced. The engine the system was grounded through (on a catamaran with twin engines) was toast, thought the second engine with its own isolated system did work after the strike. The only thing that still worked was a handheld VHF.
Autopilot, compass light, refrigeration, even the solenoid for the propane cooking stove was all gone. Took three days to get to nearest port plotting a DR on a paper chart and using small LED flashlight while hand steering to light the compass. Not fun at all.
Sounds brutal. Where were you and how far to safe harbor?
Paul L is offline   Reply With Quote
Old 13-01-2019, 22:40   #24
Registered User

Join Date: Dec 2009
Location: Australia
Boat: building Roberts Mauritius 43ft
Posts: 736
Re: Lighting strike on an all electric boat????

A friend of a friend was in a 40ft fishing boat 30 mile off the West Coast of Australia. They were hit by lightning. The plastic instrument blew up and sprayed molten plastic over one of the guy's face, all the wiring had melted so they couldn't start the motor or use the radio.

Luckily the only boat in the area (on the horizon) saw them get hit and came to their aid. I suppose they could have used the flares if another boat came into sight otherwise the boat would have washed up in Africa about three months later with two skeletons on board.

Clive

PS Why is it that multi-hulls get hit more often than mono hulls? Do they know?
coopec43 is offline   Reply With Quote
Old 13-01-2019, 23:24   #25
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 8,595
Images: 69
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by coopec43 View Post

PS Why is it that multi-hulls get hit more often than mono hulls? Do they know?
Some theories are that a greater proportion of multis inhabit the tropics and that they may tend to anchor in shallower water.
44'cruisingcat is online now   Reply With Quote
Old 14-01-2019, 04:26   #26
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: 33,686
Images: 240
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by coopec43 View Post
I understand where you are coming from. Even the "experts" don't fully understand lightning - why lightning is attracted to sharp/pointy edges ...
Actually, it's not. Rounded tips are more attractive.


“... An examination of the relevant physics shows that very strong electric fields are required above the tips of rods in order that they function as strike receptors but that the gradients of the field strength over sharp-tipped rods are so great that, at distances of a few millimeters, the local fields are often too weak for the development of upward-going streamers. In field tests, rods with rounded tips have been found to be better strike receptors than were nearby sharp-tipped rods ...”
~ Charles B. Moore, Langmuir Laboratory for Atmospheric Research, New Mexico Institute of Mining and Technology, Socorro, NM

https://journals.ametsoc.org/doi/ful...L%3E2.0.CO%3B2
__________________
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 14-01-2019, 04:58   #27
Registered User

Join Date: Dec 2009
Location: Australia
Boat: building Roberts Mauritius 43ft
Posts: 736
Re: Lighting strike on an all electric boat????

[QUOTE=GordMay;2801948]Actually, it's not. Rounded tips are more attractive.
In field tests, rods with rounded tips have been found to be better strike receptors than were nearby sharp-tipped rods ...”
~ Charles B. Moore, Langmuir Laboratory for Atmospheric Research, New Mexico Institute of Mining and Technology, Socorro, NM

QUOTE]


Now I am confused........

I quote from a science paper written in 2014.

A fundamental principle of static electricity is that all objects emit charges through the process of ionization, and sharp objects emitcharges faster than flat or rounded planes. This partly explains why lightning strokes hit corners and sharp points of a building more often than the flat sides.


That is why I have ground strips as opposed to plates as there are more sharp edges on a strip than a plate.

When I get a chance I will do more research........

Clive
coopec43 is offline   Reply With Quote
Old 14-01-2019, 04:59   #28
Registered User

Join Date: Aug 2017
Posts: 8
Re: Lighting strike on an all electric boat????

What about Aluminum boats? Are they better protected? Are they more or less closer to a Farraday's cage? As far as I know current at high voltage flows over the surface (most of it). And hopefully discharge directly into the water...
Dirk01 is offline   Reply With Quote
Old 14-01-2019, 05:24   #29
Registered User

Join Date: Dec 2009
Location: Australia
Boat: building Roberts Mauritius 43ft
Posts: 736
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by GordMay View Post
Actually, it's not. Rounded tips are more attractive.

In field tests, rods with rounded tips have been found to be better strike receptors than were nearby sharp-tipped rods ...”
~ Charles B. Moore, Langmuir Laboratory for Atmospheric Research, New Mexico Institute of Mining and Technology, Socorro, NM

This makes for fascinating reading.

A Malaysian woman changed the world’s view on lightning, but what did she discover anyway? Badd25/03/2018

https://cilisos.my/a-malaysian-woman...scover-anyway/


Robiah's method, later known as the Collection Surface Method (CSM), is based on the observed lightning damage to buildings instead of power lines. It allows engineers to predict lightning strike locations on a building and design an effective lightning protection system by placing lightning rods at the predicted locations – a technique which was never before developed by any scientist



Clive
coopec43 is offline   Reply With Quote
Old 14-01-2019, 05:48   #30
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: 33,686
Images: 240
Re: Lighting strike on an all electric boat????

Quote:
Originally Posted by coopec43 View Post
... Now I am confused........
... That is why I have ground strips as opposed to plates as there are more sharp edges on a strip than a plate.
Blunt or rounded (but not flat) Air Terminals have been shown to be slightly more effective than sharp Lightning Rods, because they have lower breakdown voltages, and longer time to breakdown compared, to other air terminals*
The results of studies suggest that moderately blunt metal rods (with tip height–to–tip radius of curvature ratios of about 680:1) are better lightning strike receptors than are sharper rods or very blunt ones.
Dr. Charles B. Moore et al, reported* that the electric fields above the blunter rods were as much as two times stronger over greater distances than those above the sharp rods. This, he said, ''can be significant in the possible interception of an approaching lightning streamer.''
Moreover, Dr. Moore said, “the sharp rods create around their tips a dense sheath of electrified, or ionized, particles, which reduce the probability of lightning's striking the rod. In so protecting itself from lightning, instead of drawing it, the rod is not as likely to fulfill its intended function of diverting lightning from other exposed objects in the vicinity. “

Goto: Lightning Rod Improvement Studies
By C. B. Moore, William Rison, James Mathis, and Graydon Aulich
Langmuir Laboratory for Atmospheric Research (New Mexico Tech)
https://journals.ametsoc.org/doi/abs...-0450-39.5.593

The most recommended lightning ground electrode is a long strip, perhaps 4" wide x 1/4" minimum thick, and 36" minimum long, installed on the outside of the hull, from the base of the mast, leading aft. The ends should be secured with two fasteners, to prevent “twisting” under dynamic loading. Strips are recommended due to their increased “edge length”, which form better attachments than flat surfaces. Do not fair the edges, but allow them to remain in “sharp” contact with the water.

External Ground Plate

Ewen M. Thomson has patented a new electrode geometry, claimed to be more effective.
Goto ➥ Marine Lightning Protection Inc.
and see the patent at:
http://www.marinelightning.com/USPTO...708638_001.pdf
__________________

__________________
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
Reply

Tags
boat, electric, lighting

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
Rewiring for all LED Lighting pcmm Electrical: Batteries, Generators & Solar 33 04-10-2015 16:30
Adding 12v lighting to non-electric outboards? sailalibi Engines and Propulsion Systems 3 05-03-2015 21:13
Question for all you boat electric guru's ShaktisBoy Electrical: Batteries, Generators & Solar 25 24-11-2013 21:52
For Sale: Electric Motors and hydraulic electric lifter arms 4 sale Sea Shoes Classifieds Archive 0 25-03-2012 08:46



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:38.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.