Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-12-2007, 06:40   #16
Registered User
 
Viking Sailor's Avatar

Join Date: Nov 2006
Location: San Francisco Bay
Boat: Fantasia 35 - s/v Feeling Good
Posts: 1,074

READING LIGHTNING'S PALM

Outside this ragged darkening cloud
air grows heavy, cringes
while inside, tension builds

a forked tongue flickers
squanders all
in one great leap to earth
or to the heavens

air breathes out
-but inside the cloud
tension builds again.

This story older
than recorded history
dinosaurs
our planet's green
-the spark, perhaps
that kindled life.

Looking up, we see it
rip the helpless sky,
we marvel at its power
to scorch forests
wreck cathedrals
put out a city's lights
weave glass serpents
in the desert sand.

Looking down, as now we can,
our globe scintillates
always
-flurries of dagger-strokes
accompanying great storms
over oceans
jungles, mountains

a fireworks show
blazoning messages
in code
which we must crack.

J. Latham


Here is a link to NASA's pages on lightning:

Lightning and Atmospheric Electricity at the GHCC

Here is a link to NASA global lightning flash data:

http://thunder.msfc.nasa.gov/data/qu...04/mission.png

The biggest problem is in defining what constitutes "lightning protection". I believe that lightning protection for a sailboat should be defined has: Methods and techniques that minimize the risk of injury to crew and damage to the hull. Electronics maybe a cost issue, but if the crew is un-injured and the boat is still afloat then survival is possible.
__________________

__________________
Viking Sailor is online now   Reply With Quote
Old 15-12-2007, 15:39   #17
Registered User

Join Date: Sep 2007
Location: Queensland, Australia
Boat: Piver Loadstar 12.5 metres
Posts: 374
Lightning Protection

Firstly Gordon--I made my living as a salaried officer of a then government entity--I did not have to sell anything to anybody.

I merely recommended things and installed stuff--and because I had plenty of experience fixing the damage caused by lightning and the associated magnetic pulse I think I can debunk a lot of stuff based on experimental data obtained in a contrived situation so remote from the variables of a lightning strike that the data is often irrelevant. One would need a HUGE Van der Graaf gennie to produce the millions of volts present in a small strike--let alone a large linked-up pulsating (and sometimes reversing) discharges. The best laboratory is reality, the best observations come from the field. Only component testing can be done in a laboratory--to a fairly limited extent.

How effective lightning protection is depends on the speed at which charges can be collected and earthed. The thicker the wires the faster the discharge--and the better the protection.

Firstly--almost any protection no matter how ineffective is better than no protection at all. Another result looking for a good cause is the use of air gaps. I would not recommend any charge-concentrationg devices like air-gaps. Yes you get a bigger spark when it flashes into a bucket--because these breaks in conductivity introduce a high resistance which does allow for the collection of a bigger charge before the gap, however small, is jumped. This does not mean it works any better.

Lightning arrestors are protection for working circuits from high voltages, usually induced either magnetically or electrostatically. Such arrestors require first class earthing systems. They are simple isolating devices designed to prevent working currents running to earth at low voltages--up to about 300 volts. Over this value the arrestor allows conduction. The higher voltages, potential difference, charges etc quickly run to earth and when the voltage falls to below the design parameter the current stops and normal use of the circuits return. They are not designed to conduct lightning strikes. They are designed to protect equipment from high induced potentials, capacitive or, in the case of a nearby discharge, inductive.

Now, to the question of introducing dissimilar metals such as copper into a circuit made of aluminium and zinc, (the galvanising of the chain and anchor) I would instead fit aluminium, and if the mast is very light in gauge I would carry it to the top of the mast. I do not particiularly like sharp turns in lightning protection, because they greatly magnify the concentration of charge at the curve as they are in operation. That said, I have seen plenty of sharply curved lightning protection straps which worked effectively--but as I said before--the only damage I ever saw was from good lightning protection systems either improperly fitted (earth rods disconnected or severely corroded was the usual problem) or simply not fitted at all because someone thought them unnecessary.

Not fitting proper lightning protection is like walking through the African bush without a rifle at night. You might get away with it for years--but if you continue to do it in an area where hazards exist, one day a buffalo will stomp the crap out of you, or you might get the chomp from a lion. The fact is that getting away with for extended periods of time does not really qualify anyone to advise others not to bother with protection.

Most of the photographs I have seen of lightning apparently striking a lightning conductor are long time exposures, and what they are seeing is the over exposure of the ionisation of the atmospheric gas streamers during an effective but heavy bleed of charge, or several such discharges. Only a very mild strike could be carried to earth through a conductor should one occur--great luck if that is the case, but the main reason for protection is to prevent a major strike happening in the first place.

Fresh water is not as good a conductor of electricity as is salt, so it would not make as effective an earth sink. Perhaps in such an instance a set anchor using all cahin rode might be of some assistance. I used to try to get an earth value of less than one hundred ohms from two earth rods set a certain distance apart--but a sea earth is so effective that in some countries the sea itself is used to conduct power. I think New Zealand has such an earth working power cable from the North to the South Island, just to cite one example. I think Canada has such a system somewhere too--

Since the power losses in any conductor are the square of the current multiplied by the resistance--one can see how effective the ocean is at conducting electricity. Fresh water is nowhere near as conductive, and pure fresh water is a good insulator. This might be one reason boats are sometimes struck in fresh water--they are unable to dissipate the charges they collect quickly enough to prevent a serious build-up of induced charge on the vessel.

My suggestion is use the suggested connection to the anchor chain if you have an all chain rode, but drop the anchor to the lake bed, not just a couple of feet. The freshwater lake bottom will provide some sort of earth, one can only hope it good enough. In salt water tyhe use of a large area plate would be better--it is the area in contact with the water that conducts the current away. That is why I do not like lengths of chain droppe dover the sides and connected to the chainplates. They are better than nothing however.

If you want to have a proper lightning system designed for your vessel, go to some power authority engineer or even better, a radio antennae electrical person versed in lightning systems for tall radio and television towers. These regularly conduct large dissipations.

Now--if you want to make up your own protection, use a large aluminium dissipation plate connected to a low resistance path to the highest point on your mainmast. Two masts--use a couple If your vessel is a large one fit protection to each mast and never use an earth common to the electrical circuits on board. If you want to run straps to make the vessel like a Faraday cage do so by all means. There is no charge present inside a hollow conductor, but the ouitside of the cage is still vulnerable unless it is able to collect charge and run it quickly to earth.

Of course--my advice like any other has the usual disclaimer--follow it at your own risk. I have no idea whatsoever what I am talking about, but if it makes sense to you then use it at your own discretion and risk. What works for me might work for you--
__________________

__________________
Mike Banks is offline   Reply With Quote
Old 15-12-2007, 16:03   #18
Registered User
 
OldYachtie's Avatar

Join Date: Mar 2007
Location: 35 mi. north of Seattle
Boat: Building a 65' catamaran at moment
Posts: 78
An abridged version of the Profession Boatbuilder class-

Can be read at this link-

http://www.marinelightning.com/EXCHANGEOct2007Final.pdf
__________________
- People who say it cannot be done should not interrupt those who are doing it. -George Bernard Shaw
OldYachtie is offline   Reply With Quote
Old 15-12-2007, 16:18   #19
Registered User
 
cburger's Avatar

Join Date: May 2006
Location: Nyack, NY
Boat: Westsail 32
Posts: 1,548
Images: 1
Boats US says there is no evidence that any measure will protect the vessel from a potential lightning strike. I guess when it's your time it's your time?
__________________
cburger is offline   Reply With Quote
Old 15-12-2007, 17:32   #20
Registered User

Join Date: Jan 2005
Location: Seattle area (Bremerton)
Boat: C&C Landfall 39 center cockpit "Anahita"
Posts: 1,076
Images: 6
be careful with inductive reasoning

What Boat US says; "There may not be much a boater can do to prevent lightning from striking their vessel". This statement does not mean that there IS no way to protect a vessel from ANY classes of lightning strike. It means that there is no UNIVERSAL solution to prevent any and all strikes. There is a huge difference in the logic here.

Whether or not all "experts" agree with Mike Banks' theory as to the physics of various lightning strikes there are statistically known (O.K. If you insist I'll spend some time finding a few supporting technical articles) grounding methods which DO result in minimizing or preventing STATIC discharge damage.

Static discharge damage occurs with a relatively slow build up of charge resulting in a voltage gradient (measurable) in the air surrounding a masted vessel that is ungrounded. If a voltage gradient is say 5Volts per millimeter "above ground" (literally and figuratively) then if you stand on ground (or touch seawater) and touch a mast 20 meters tall then you are exposed to 100 thousand Volts! You WILL conduct a discharge current. It doesn't take much current to kill even though it may take huge amounts of current relative to a human tolerance to damage a boat. This static discharge effect is not to my knowledge challenged or questioned by any of the lightning "experts". Grounding the mast DOES force the voltage to be zero in the vicinity of the mast all along the surface.

IT is the dynamic discharge phenomena that is so difficult to predict, reproduce and study as a physics experiment. Because a vessel or building or tower protected from static discharges may be struck by dynamic lightning effects does not negate the argument to ground (get it?). Inductive reasoning in this case is flawed in that one may generalize that if grounding does not always protect against damage then it is ineffective.

I suspect that RF grounding techniques ARE quite effective yet no system can protect against the spectrum of what mother nature can produce. Does this make sense? Keep in mind that even most dynamic discharges are around 20,000 Amps or less some grounding may "work" until that 100,000 or one million Amp discharge happens, then almost anything will be toasted.

Now, who out there can claim that their vessel was grounded and still got hit by a static discharge? Who can claim that there is any reasonable way to differentiate between static and dynamic discharges? Who can differentiate between 20,000 Amp damage (theoretically protected by #6AWG copper before or at the point of vaporization) and some higher current damage?
Regards,
Rick
__________________
"I don't think there'll be a return journey Mr. Frodo". Samwise Gamgee
Rick is offline   Reply With Quote
Old 16-12-2007, 05:17   #21
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,596
Images: 240
Mike:
Sorry if I sounded like I was putting you (and/or your professionalism) down. There’s a lot of excellent (accurate) information in your several posts on the subject, and I don’t want to detract from that very helpful advice.

My only argument is with the false supposition that the likelihood of a lightning strike might be reduced by “bleeding off charge” (charge Transfer or Dissipation, & etc.) which is a thoroughly discredited hypothesis.


Quote:
Originally Posted by Mike Banks
.... If you can bleed enough charge from the air surrounding the top of your vessel, you greatly decrease the likelihood of an initial strike. Even if you are struck--very unlikely, so much of the discharge will already have taken place that your damage may be significantly lessened, but I am only theorising here because I have never seen a strike of any kind on properly protected plant...
See William Rison’s rebuttal of the Charge Transfer hypothesis

There Is No Magic To Lightning Protection:
Charge Transfer Systems Do Not Prevent Lightning Strikes

http://www.lightningsafety.com/nlsi_lhm/magic.pdf

In which he concludes:
“... we are opposed to CTS’s because the underlying theory claimed for them is scientific nonsense, and because every independent study of them demonstrates that they do not prevent lightning. Charge Transfer Systems and Early Streamer Emission air terminals are modern incarnations of the “magic” wares peddled by Melville’s Lightning Rod Man — ornate devices with no independent evidence that they live up to their fantastic claims, sold by a slick salesman who preys on his customers’ fear of lightning and exploits their limited knowledge of lightning protection.”

See also:

Scientists Oppose Early Streamer Air Terminals ~ By Abdul M. Mousa
Scientists Oppose Early Streamer Air Terminals - National Lightning Safety Institute

“I wish to make readers aware of the extent of the opposition of the scientific community to Early Streamer Emission (ESE) lightning rods. In an unprecedented move, 17 scientists who are members of the Scientific Committee of ICLP (International Conference on Lightning Protection) issued a joint statement opposing ESE lightning rod technology...”

Charge Transfer System is Wishful Thinking, Not Science ~ by Charles B. Moore
Charge Transfer System is Wishful Thinking, Not Science - National Lightning Safety Institute

A Critical Review of Non-Conventional Approaches to Lightning Protection
by M. A. UMAN AND V. A. RAKOV

http://ams.allenpress.com/archive/15...83-12-1809.pdf


Conventional and Un-conventional Lightning Air Terminals: An Overview
by Hartono Zainal Abidin & Robiah Ibrahim
http://www.lightningsafetyalliance.com/documents/acem_air_terminals.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 offline   Reply With Quote
Old 16-12-2007, 16:47   #22
Registered User

Join Date: Jan 2005
Location: Seattle area (Bremerton)
Boat: C&C Landfall 39 center cockpit "Anahita"
Posts: 1,076
Images: 6
William Rison's article and our boats

Gord's previous submission contains an excellent no-nonsense article by William Rison. Of particular interest to us is this quote from that article:

[The principles of traditional lightning protection are basic — 1) provide preferential strikes point for lightning
(an array of conductors higher than the objects being protected), a good grounding system, and conductors
between the two to conduct the damaging current from a lightning discharge away from the structure to
be protected; and 2) provide appropriate transient protection on power and signal wires entering the structure
to protect equipment and personnel from the effects of induced lightning currents. What does it take
to provide complete protection from lightning? It requires a means to ensure that the currents from a direct
strike cannot enter the structure, and electrical transients induced from lightning are prevented from getting
into the structure. To prevent the currents from a direct lightning strike from entering Kiva II, it was constructed
of 1/4” steel, with only a few openings for signal and power wires to enter. To prevent transients
from entering Kiva II, every signal and power wire entering into it are equipped with appropriate transient
suppression devices.
It is impractical to build most structures with absolute protection from lightning.]

From the above quote we can glean that one NECESSARILY SHOULD ground everything possible on a boat to gain some protection. In addition, as I have noted in other submissions, one cannot protect sensitive electronics (IEEE 1100 standard) without completely enclosing them in ferrous containers. Non-ferrous Faraday shields do not prevent time varying and space varying magnetic fields from penetrating and inducing damaging currents within the structures of sensitive electronics.
__________________
"I don't think there'll be a return journey Mr. Frodo". Samwise Gamgee
Rick is offline   Reply With Quote
Old 17-12-2007, 07:57   #23
Senior Cruiser
 
schoonerdog's Avatar

Cruisers Forum Supporter

Join Date: May 2004
Location: annapolis
Boat: st francis 44 mk II catamaran
Posts: 1,174
Images: 4
Putting this into practice:

OK, an aluminum cable should be led down the mast from an aluminum spike above the mast down through the deck to the water and connecting to a discharge plate. Any recommendations for specific gauges for cables and where to buy such aluminum cable?

Specific size of the aluminum plate that would be in the water?

Tips for securing to mast?

For my particular boat it should be easy as the anchor locker sits below the mast and the drain for the anchor locker makes a convenient hole right below the mast as well.

Last, as this is aluminum, will this increase the galvanic activity on the saildrives? Should a zinc be connected to the aluminum plate?
__________________
schoonerdog is offline   Reply With Quote
Old 17-12-2007, 15:08   #24
Registered User

Join Date: Sep 2007
Location: Queensland, Australia
Boat: Piver Loadstar 12.5 metres
Posts: 374
Aluminium power distribution cable would be fine. You may be able to get some from a scrap metal dealer. The discharge plate should be as big as you can make it. If you like you can fit more than one of them, and it should be possible to have them like lee boards if you wish to join the chain plates to them as well. I have not bothered--but I may do so someday if I get another piece of scrap alloy plate.

Aluminum will work as a sacrificial anode if there is no zinc anodic protection present. One could certainly bolt one to the discharge plate if it is to remain in the water. The entire plate will have to be lifted and scrubbed occasionally, or just lowered as needed.

Just as it is fond imagining that a tiny boat mast with its pointed collector can discharge moving areas of charge five to eight miles above it, it is equally senseless to imagine a lighning rod and associated wires as described could safely conduct to earth a surge which, in a moderate strike, might be the power equivalent of twenty million volts and ten thousand amps. In fact a moderate strike can be as much as twice this power.

Effective protection is the prevention of powerful strikes or even minor strikes by making the air above and around he vessel less likely to become ionised. It is the ionised air that allows the establishment of an initial stroke--then the main surge can occur.

So far I have seen nothing which convinces me that the effectivemness of lightning protection depends on coinducting a strike to earth, but that any potential strike is defused by making its likelihood or strength considerably less. I have never seen full-on strike in unprotected plant. I have been close to protected plant when considerable surges of current went down the lighning protection system without a visible strike occurring and this was mid-afternoon.

Severe strikes are quite rare. Most local strikes are moderate at most. There have been cases of peiople surviving small lightning strikes--and these are about all a small boat conduction system could habdle were it not for other factors where charge intensity and the surrounding atmospheric charge density reduction denied or not by some, undoubtedly contribute.
__________________
Mike Banks is offline   Reply With Quote
Old 17-12-2007, 15:24   #25
Registered User

Join Date: Sep 2007
Location: Queensland, Australia
Boat: Piver Loadstar 12.5 metres
Posts: 374
Aluminium power distribution cable would be fine. You may be able to get some from a scrap metal dealer. The discharge plate should be as big as you can make it. If you like you can fit more than one of them, and it should be possible to have them like lee boards if you wish to join the chain plates to them as well. I have not bothered--but I may do so someday if I get another piece of scrap alloy plate.

Aluminum will work as a sacrificial anode if there is no zinc anodic protection present. One could certainly bolt one to the discharge plate if it is to remain in the water. The entire plate will have to be lifted and scrubbed occasionally, or just lowered as needed.

Just as it is fond imagining that a tiny boat mast with its pointed collector can discharge moving areas of charge five to eight miles above it, it is equally senseless to imagine a lighning rod and associated wires as described could safely conduct to earth a surge which, in a moderate strike, might be the power equivalent of twenty million volts and ten thousand amps. In fact a moderate strike can be as more than twice this power.

Effective protection is the prevention of powerful strikes or even minor strikes by making the air above and around he vessel less likely to become ionised. It is the ionised air that allows the establishment of an initial stroke--then the main surge can occur as other charged portions of the atmosphere opportunistically link up and dump their charges too.

So far I have seen nothing which convinces me that the effectiveness of lightning protection depends purely on conducting a strike to earth. That would be a lovely consequence, but I believe that any potential strike is defused by making the air around the vessel devoid of charge. This makes any likelihood of a strike considerably less.

I have never seen full-on strike in unprotected plant. I have been close to protected plant when considerable surges of current went down the lighning protection system without a visible strike occurring and this was mid afternoon.

Fortunately, severe strikes are quite rare. Most local strikes are moderate at most. The strikes shown hitting lightning collectors are often a sustained heavy discharge within the capability of the system--a small strike at the very most. There have been cases of people surviving small lightning strikes. A mild strike is about all a small boat conduction system could handle were it not for other factors where surrounding atmospheric charge density reduction undoubtedly contribute.
__________________
Mike Banks is offline   Reply With Quote
Old 17-12-2007, 16:33   #26
cruiser

Join Date: Aug 2005
Location: No longer post here
Boat: Catalac Catamaran
Posts: 2,462
back to square one

Is anyone else as confounded as I am? We have Gord saying "false supposition that the likelihood of a lightning strike might be reduced by “bleeding off charge”

And Mike saying thats what the protection systems are for as "it is equally senseless to imagine a lighning rod and associated wires as described could safely conduct to earth a surge "

So if I'm reading this correctly, we can't preempt a strike (Gord) and can't conduct the current if we are hit (Mike). I'm back to square one. These gentlemen have argued this thread to a standoff.

An informal survey here in central Florida suggests that properly bonded/grounded boats are twice as likely to be hit by lightning as an ungrounded boat.
__________________
Tropic Cat is offline   Reply With Quote
Old 17-12-2007, 21:48   #27
Registered User

Join Date: Sep 2007
Location: Queensland, Australia
Boat: Piver Loadstar 12.5 metres
Posts: 374
Rick--you only quoted half the sentence--of course the system will conduct a surge--just not a surge of 10 to the 12 watts--a moderate strike.

The fact that they do not attract strikes of this magnitude instead of making them unlikely pretty much explains how well they do reduce the possibility of ionising the air and facilitating such a strike.

Most lightning systems on a boat, mine included will carry only about 200 to 300 amperes. Enough to discharge the vessel and its immediate surrounds in a few milliseconds at most--provided that the earth plate is sufficiently large and of similar resistance to the cable at the plate to saltwater junction. A low resistance here is essential.

Side flashes will always occur when the discharge plate is too small just as it does on a steel tower incorrectly earthed. The lightning will flash from the tower to guy wires which are correctly earthed, usually below the first set of insulators. It is vital if a strike is to be prevented or minimised to have the ship discharged as quickly or more quickly than charge can accumulate on it.

Lightning is not a simple spark jumping from one charged conductor to another as so many try to demonstrate in a lab. This sort of tiny-tots demo loses me immediately because lightning is entirely unpredictable due to the vast number of variables present. High voltages ionise gasses--and theere are millions of volts present. Even with radar the charged areas are not visible, only some of their effects after they have happened. The reality is far more complex and interesting.

I have sat on the ground eating a sanger in the middle of a sunny afternoon after fitting an array of gaseous arrestors to a junction block--only to have them all go off as the lines not yet in use collected charge and dumped it to earth. There is an accoustic shock--so they sound like a string of penny crackers. No mistaking the fact that they have conducted some current to earth. These arrestors fire at over three hundred volts. Of course they collected it from the atmosphere--there was no other source of induced power present or operative at the time, but there was a bit of thunderstorm activity forecast.

Now one could not fit such arrestors in a line designed to carry a moderate strike to earth. They can only carry a fairly limited current. Most air gap dischargers need five hundred to a thousand volts before they conduct. Trouble is--if you let that kind of potential build up on your vessel you are just asking for trouble.

I do not think Gord is arguing against the use of protection--just the principles on which an effective system operates. He says it is all of one and none of the other. I believe it too be a good bit of one and a heck of a lot of the other as far as prevention is concerned.
__________________
Mike Banks is offline   Reply With Quote
Old 18-12-2007, 02:48   #28
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,596
Images: 240
Quote:
Originally Posted by Mike Banks
“... I do not think Gord is arguing against the use of protection--just the principles on which an effective system operates. He says it is all of one and none of the other. I believe it too be a good bit of one and a heck of a lot of the other as far as prevention is concerned ”
EXACTLY! (Actually, the presence a proper Lightning Mitigation System may slightly increase the likelihood of a structure being struck)

I have previously argued passionately for a conventional Lightning Mitigation system, consisting of Air Terminal(s), Down Conductor(s), and Grounding Electrode(s); and recommended use of an Equalization Bus.

As Mike has indicated, a Lightning Mitigation system may often be a sacrificial assembly, such as zinc anodes & safety belts.

ABYC recommends a minimum COPPER down conductor size of #6 AWG (13.3mm* or 24,358 CM**).
The equivalent Aluminum conductor would be #4 AWG (21.2mm or 37,3760 CM).

I recommend a more robust down conductor: #2 AWG Copper (33.6 mm or 62,450 CM); or #1/0 AWG Aluminum (53.5 mm or 98,980 CM).

* Approximate metric equivalents only. Use next larger Standard cable size available.
** Circular Mils

Be very careful when assembling Aluminum joints and connections.
Except on Alloy Yachts, I much prefer Copper over Aluminum conductors.

Some further light reading on the subject:
NFPA 780 - Report of the Committee on Lightning Protection
http://www.nfpa.org/Assets/Files/PDF/ROP/780-08-ROP.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 offline   Reply With Quote
Old 18-12-2007, 10:18   #29
CF Adviser

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Wherever our boat is; Playa Zaragoza, Isla Margarita
Boat: 1994 Solaris Sunstream 40
Posts: 2,439
I have personally witnessed an ungrounded boat, under anchor, struck by lightening in fresh water (Georgian Bay). The result, apart from fried electronics, were literally thousands of pinholes through the hull just below the waterline.

Perhaps I am mistaken (and I am certainly not an electrical engineer), but I had thought that it was generally accepted that the risk of such hull damage is greatly reduced if an effort has been made to ground the mast/standing rigging to a copper plate below the water line. I have and will continue to operate under this assumption unless/until I receive some very solid proof that it does not.

Grounding the mast, as has been pointed out, is generally not too difficult. The real difficulty is in grounding the standing rigging in a boat internally, even at the time of construction; it is a virtual impossibility in a completed vessel. I have used automotive jumper-cable clips to temporarily attach heavy gauge, uninsulated copper wire to the forestay/backtstay and shrouds on my boat. The wire is then run down to the water in a gentle loop. While under anchor this has provided me with at least a SENSE of additional security; I have never attempted to use the system underway.

Nevertheless, it strikes me that it (or something similar) could be used so long as the end of the cables are weighted with (hopefully) something that does not cause damage to the topsides of the boat. I'm not sure if anyone has tried this, or has any suggestions. Or am I wasting my time?

Brad
__________________
Southern Star is offline   Reply With Quote
Old 18-12-2007, 10:34   #30
Registered User
 
Triton318's Avatar

Join Date: Aug 2006
Location: Hayes, Virginia
Boat: 1962 28' Pearson Triton
Posts: 289
Benjamin Franklin did some experiments with kites and lightning. I wonder if boaters could apply any of that to lightning protection on their boats?
__________________

__________________
Jay White
S/V Dove
1962 Pearson Triton, #318
Triton318 is offline   Reply With Quote
Reply

Tags
lightning

Thread Tools
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 JusDreaming Health, Safety & Related Gear 57 03-10-2007 11:25
Keel protection Geno53 Construction, Maintenance & Refit 5 09-04-2006 18:21
NFPA 780 Lightning Protection Systems GordMay The Library 0 16-01-2006 04:53
Fuse Protection Ted Beyer Electrical: Batteries, Generators & Solar 5 17-05-2005 11:07
Lightning Protection Stede Electrical: Batteries, Generators & Solar 5 20-11-2003 18:27



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:00.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.