I just found one advertised on the site below. Has anybody got one? Love to know what you think of them. http://www.fourwinds-ii.com/fuelfits.html
- Status
Alternative
A British firm makes a clamp that goes on the mast and trails two heavy wires into the water, which sounds better than this thing for sheer effectiveness. However, these folks make the Baja filter, which gets rave reviews.
A British firm makes a clamp that goes on the mast and trails two heavy wires into the water, which sounds better than this thing for sheer effectiveness. However, these folks make the Baja filter, which gets rave reviews.
Dissipators Don't !!!
Everfair (and Others) make unsubstantiated and untrue claims - to whit: <i>“LIGHTNING MASTER STATIC DISAPATORS lower the exposure to a direct lightning strike by controlling the conditions which trigger direct strikes. LIGHTNING MASTER reduces the build up of static ground charges and retards the formation of the ion "streamers" which complete the path for a lightning strike.”</i> There is absolutely NO independent evidence supporting the claims made for “Lightning Dissipators”, or “Streamer Delaying Air Terminals” (as this week’s fashion is calling them) - ie: that they can reduce the likelihood of being struck by lightning. The best that might be said for them is that, properly installed as part of a lightning protection (bonding) system - they might be an expensive and only moderately effective air terminal (“Lightning Rod”). Perhaps I should say what I really think
A few References: http://www.uscgaux.org/~auxcen/beacon/spring03BEACON.pdf http://www.cyamsa.com.mx/acrobat/Lightning%20Elimination%202.pdf “Validity of the Lightning Elimination Claim” by Abdul M. Moussa, IEEE http://www.lightningsafety.com/nlsi_lhm/Uman_Rakov.pdf “...there has been no evidence that lightning dissipation arrays can protect a structure by dissipating electric charge...” http://www.lightningsafety.com/nlsi_lhm/charge_transfer.html From “Charge Transfer System is Wishful Thinking, Not Science” by Jodi Haasz New Mexico Institute of Mining and Technology Langmuir Laboratory for Atmospheric Research IEEE- Power Engineering Society “...The undeniable facts are that "dissipation" devices do not prevent the occurrence of cloud-to- ground lightning strikes and that they are not designed nor intended to be the preferential receptors of the lightning strikes in their vicinity. Accordingly, such devices serve no useful protective purpose in the prevention nor in the reception and conveyance of lightning to Earth. In my opinion, the "Charge Transfer System" method does not have technical merit for lightning protection and there is little probability that it will acquire any technical merit in the future...” http://www.ees-group.co.uk/downloads/ESE%20paper.PDF “Evaluation of Early Streamer Emission Air Terminals” by McIvor, Carpenter, & Drabkin “...There is limited test data on EST performance, an no available data substantiates the suppliers’ claims...-...The physics related to the situation, as provided by the atmospherics physics community, demonstrate that the claims made for all of these ESE devices are wildly exaggerated...” And from theother side - advocates of “Dissipation” products (All Manufacturers): Alltec Corporation offers a complete line of Lightning Dissipation Terminals utilizing the Point Discharge Principle to mitigate direct lightning strikes: http://www.allteccorp.com/services/services-images/point-discharge.pdf http://www.allteccorp.com/services/articles/point-discharge1202.html OMH(Informed)O Gord
Everfair (and Others) make unsubstantiated and untrue claims - to whit: <i>“LIGHTNING MASTER STATIC DISAPATORS lower the exposure to a direct lightning strike by controlling the conditions which trigger direct strikes. LIGHTNING MASTER reduces the build up of static ground charges and retards the formation of the ion "streamers" which complete the path for a lightning strike.”</i> There is absolutely NO independent evidence supporting the claims made for “Lightning Dissipators”, or “Streamer Delaying Air Terminals” (as this week’s fashion is calling them) - ie: that they can reduce the likelihood of being struck by lightning. The best that might be said for them is that, properly installed as part of a lightning protection (bonding) system - they might be an expensive and only moderately effective air terminal (“Lightning Rod”). Perhaps I should say what I really think
A few References: http://www.uscgaux.org/~auxcen/beacon/spring03BEACON.pdf http://www.cyamsa.com.mx/acrobat/Lightning%20Elimination%202.pdf “Validity of the Lightning Elimination Claim” by Abdul M. Moussa, IEEE http://www.lightningsafety.com/nlsi_lhm/Uman_Rakov.pdf “...there has been no evidence that lightning dissipation arrays can protect a structure by dissipating electric charge...” http://www.lightningsafety.com/nlsi_lhm/charge_transfer.html From “Charge Transfer System is Wishful Thinking, Not Science” by Jodi Haasz New Mexico Institute of Mining and Technology Langmuir Laboratory for Atmospheric Research IEEE- Power Engineering Society “...The undeniable facts are that "dissipation" devices do not prevent the occurrence of cloud-to- ground lightning strikes and that they are not designed nor intended to be the preferential receptors of the lightning strikes in their vicinity. Accordingly, such devices serve no useful protective purpose in the prevention nor in the reception and conveyance of lightning to Earth. In my opinion, the "Charge Transfer System" method does not have technical merit for lightning protection and there is little probability that it will acquire any technical merit in the future...” http://www.ees-group.co.uk/downloads/ESE%20paper.PDF “Evaluation of Early Streamer Emission Air Terminals” by McIvor, Carpenter, & Drabkin “...There is limited test data on EST performance, an no available data substantiates the suppliers’ claims...-...The physics related to the situation, as provided by the atmospherics physics community, demonstrate that the claims made for all of these ESE devices are wildly exaggerated...” And from theother side - advocates of “Dissipation” products (All Manufacturers): Alltec Corporation offers a complete line of Lightning Dissipation Terminals utilizing the Point Discharge Principle to mitigate direct lightning strikes: http://www.allteccorp.com/services/services-images/point-discharge.pdf http://www.allteccorp.com/services/articles/point-discharge1202.html OMH(Informed)O GordGord....its pretty clear that your on one side
of this issue... and the jury is far from in which side is right. Its interesting that opponents to these devices keep putting words into the advertising saying that there is no way they can prevent strikes. I yet fail to see where the ion diffuser adds have ever claimed to prevent them... wouldn't that be a silly thing to do. In fact, what I'm seeing mostly is... the other guys product doesn't work, buy mine. It sticks in the craw that the other guy can sell a product that is not proven to totally retard lightning strikes yet those who sell a single point dispersion device aka lightning rod... can attest to the fact that they take plenty of hits and if you will only ground the mast really really well... you may get by without any hull dammage and the only thing that will need replaced is all the on board electronics. I think these soothsayers and followers of voodoo electrical engineering led by the Florida Sea Grant Study have had their day and come up short. Heck... even one fellow Florida University professor contradicts the Sea Grant theory and suggest rather straightforward that a lightning rod may very well increase ones chances of being hit. Until the jury is in...no side of this issue should take an assuming attitude... because either could be right or wrong.
of this issue... and the jury is far from in which side is right. Its interesting that opponents to these devices keep putting words into the advertising saying that there is no way they can prevent strikes. I yet fail to see where the ion diffuser adds have ever claimed to prevent them... wouldn't that be a silly thing to do. In fact, what I'm seeing mostly is... the other guys product doesn't work, buy mine. It sticks in the craw that the other guy can sell a product that is not proven to totally retard lightning strikes yet those who sell a single point dispersion device aka lightning rod... can attest to the fact that they take plenty of hits and if you will only ground the mast really really well... you may get by without any hull dammage and the only thing that will need replaced is all the on board electronics. I think these soothsayers and followers of voodoo electrical engineering led by the Florida Sea Grant Study have had their day and come up short. Heck... even one fellow Florida University professor contradicts the Sea Grant theory and suggest rather straightforward that a lightning rod may very well increase ones chances of being hit. Until the jury is in...no side of this issue should take an assuming attitude... because either could be right or wrong.
So are there any solutions ?
Are there any other recommendations that anyone can make to lessen the chances of a strike. I have be told that it is a good idea to attached jumper cables to your shrouds and drop them overboard so that if you are struck you will lessen the damage.
Are there any other recommendations that anyone can make to lessen the chances of a strike. I have be told that it is a good idea to attached jumper cables to your shrouds and drop them overboard so that if you are struck you will lessen the damage.
J Simmonds
I have read that same thing in several cruising books, most recently in Tom Neale's "All in the same boat". Regards, -Jim- s/v Forever
I have read that same thing in several cruising books, most recently in Tom Neale's "All in the same boat". Regards, -Jim- s/v Forever
Check the tread over at Big Boats
I explain what happened to my boat. What I forgot to say is that, when struck, I had just installed a Forespar Lightening Master. (or whatever they'er called). The picture of my masthead on my web site, shows the same dissipater. Note that it's deformed from the strike. After the rig was properly grounded, no more strikes. Just my experience.
I explain what happened to my boat. What I forgot to say is that, when struck, I had just installed a Forespar Lightening Master. (or whatever they'er called). The picture of my masthead on my web site, shows the same dissipater. Note that it's deformed from the strike. After the rig was properly grounded, no more strikes. Just my experience.
What action?
It depends. If your mast is grounded and if you have an inboard it probably is by an electrical lighting, instrument or coax shield, then in my opinion, its prudent to provide a worthy ground that will handle a strike. The same is true if outboard powered and hooked up to shore power. If however you have an outboard, chances are that the mast is isolated... and if so, its decision time. To ground or not to ground is the question. In my opinion in fresh water... forget grounding as a ground would be less than adequate any way it was done and why risk inviting the monster aboard, if your not adequately prepared to deal with it. If the mast is isolated, then its possible to have protection and keep it isololated by using an arrestor. Rather than jumper cables on the stays of an isolated mast, which turns the mast into a grounded mast and possilby inviting a strike... a welding cable wrapped around the mast base with 8-10 feet of stripped cable on each end in the water and holes in the insulation where wrapped around the mast to provide an arrestor if a hit might be the way to go. The advantages of isolation would be preserved.
It depends. If your mast is grounded and if you have an inboard it probably is by an electrical lighting, instrument or coax shield, then in my opinion, its prudent to provide a worthy ground that will handle a strike. The same is true if outboard powered and hooked up to shore power. If however you have an outboard, chances are that the mast is isolated... and if so, its decision time. To ground or not to ground is the question. In my opinion in fresh water... forget grounding as a ground would be less than adequate any way it was done and why risk inviting the monster aboard, if your not adequately prepared to deal with it. If the mast is isolated, then its possible to have protection and keep it isololated by using an arrestor. Rather than jumper cables on the stays of an isolated mast, which turns the mast into a grounded mast and possilby inviting a strike... a welding cable wrapped around the mast base with 8-10 feet of stripped cable on each end in the water and holes in the insulation where wrapped around the mast to provide an arrestor if a hit might be the way to go. The advantages of isolation would be preserved.
DO WHAT THE POWER COMPANIES DO
Lightning is a frequent event in electric substations, and power co.s follow IEEE recommendations. Sailboaters cannot expect an "ungrounded mast" to be any different than grounded. If lightning strikes, it will travel through the mast, blow a hole through the deck and hull, and dissipate into the water. The air gap in the cabin is trivial to a strike that has already traveled 15,000 to 50,000 feet. A large cable solidly connected to the mast and trailed ten feet or so in the water will provide a much less destructive path. Two ends on opposite sides of the boat are even better. In an emergency, shackle your anchor chain to a shroud, and let it hang in the water. This will give some protection from small strikes. I have seen, personaly present at the strike, strikes carried to ground by #2 wire without damage, and have seen the results of a huge bolt that evaporated a half inch cable. Fortunately, most strikes are small.
Lightning is a frequent event in electric substations, and power co.s follow IEEE recommendations. Sailboaters cannot expect an "ungrounded mast" to be any different than grounded. If lightning strikes, it will travel through the mast, blow a hole through the deck and hull, and dissipate into the water. The air gap in the cabin is trivial to a strike that has already traveled 15,000 to 50,000 feet. A large cable solidly connected to the mast and trailed ten feet or so in the water will provide a much less destructive path. Two ends on opposite sides of the boat are even better. In an emergency, shackle your anchor chain to a shroud, and let it hang in the water. This will give some protection from small strikes. I have seen, personaly present at the strike, strikes carried to ground by #2 wire without damage, and have seen the results of a huge bolt that evaporated a half inch cable. Fortunately, most strikes are small.
Not so, Arlyn
ARLYN: I am on the side of rational judgement - not a "buy mine" self-interested point of view. Obviously, you didn’t read any of the references I listed (including a proponent of “dissipators”). You might also review "Professional Boatbuilder", issues 49 & 50. Were this a court case, the Judge would direct a verdict (against “dissipators”) for lack of evidence. Ion Diffuser (and the names change weekly) ads have presented the buyer with a moving target as to their claims. At one time they claimed to PREVENT lightning strikes (and even offered a guarantee - which they couldn’t honor), and more lately to reduce the likelihood of a strike. Likewise their theory of operation has changed - as each theory has (in turn) been discounted by Academics studying lightning phenomenon. The disparagement of Lightning Dissipation theory is virtually universal (not limited to Ewan Thompson, PhD - Florida Sea Grant); whereas these (various) dissipation theories are prounded only by suppliers of product (who obviously have a self-interest). There is a maxim that says - “extraordinary claims require extraordinary evidence”. It is incumbent upon the manufacturers of “dissipators” to support any claims for efficacy they make. They have failed to substantiate any claims. The researchers (with no evident self-interest), on the other hand present a preponderance of counter evidence. The jury is in - there is no reason to believe that “dissipators” work. Your second posting suggest that and “isolated” mast might best be protected with an arrestor. There is NO SUCH THING as an effectively isolated (against lightning) mast! SEE NORMAN’s POST !!! Your description of a welding cable “arrestor” is ludicrous. A Lightning Arrestor (Surge Suppressor, or Transient Voltage Sure Suppressor) is generally considered to be a device that prevents the peak voltage from going above a certain threshold such as plus-or-minus 200 volts. Semiconductor devices (that can conduct electricity under some conditions but not others) are used for this purpose. What you’ve described MIGHT be a sort of crude sort of “grounded choke” coil. Respectfully, Gord
ARLYN: I am on the side of rational judgement - not a "buy mine" self-interested point of view. Obviously, you didn’t read any of the references I listed (including a proponent of “dissipators”). You might also review "Professional Boatbuilder", issues 49 & 50. Were this a court case, the Judge would direct a verdict (against “dissipators”) for lack of evidence. Ion Diffuser (and the names change weekly) ads have presented the buyer with a moving target as to their claims. At one time they claimed to PREVENT lightning strikes (and even offered a guarantee - which they couldn’t honor), and more lately to reduce the likelihood of a strike. Likewise their theory of operation has changed - as each theory has (in turn) been discounted by Academics studying lightning phenomenon. The disparagement of Lightning Dissipation theory is virtually universal (not limited to Ewan Thompson, PhD - Florida Sea Grant); whereas these (various) dissipation theories are prounded only by suppliers of product (who obviously have a self-interest). There is a maxim that says - “extraordinary claims require extraordinary evidence”. It is incumbent upon the manufacturers of “dissipators” to support any claims for efficacy they make. They have failed to substantiate any claims. The researchers (with no evident self-interest), on the other hand present a preponderance of counter evidence. The jury is in - there is no reason to believe that “dissipators” work. Your second posting suggest that and “isolated” mast might best be protected with an arrestor. There is NO SUCH THING as an effectively isolated (against lightning) mast! SEE NORMAN’s POST !!! Your description of a welding cable “arrestor” is ludicrous. A Lightning Arrestor (Surge Suppressor, or Transient Voltage Sure Suppressor) is generally considered to be a device that prevents the peak voltage from going above a certain threshold such as plus-or-minus 200 volts. Semiconductor devices (that can conduct electricity under some conditions but not others) are used for this purpose. What you’ve described MIGHT be a sort of crude sort of “grounded choke” coil. Respectfully, Gord
Why do we have static wicks on jets then?
If someone is so certain these "dispersers" don't work, why do we have static wicks on jet aircraft? These have been around for a long time to dissapate the static build-up before a big jolt causes damage. I realize it's not a direct comparison, but it's close.
If someone is so certain these "dispersers" don't work, why do we have static wicks on jet aircraft? These have been around for a long time to dissapate the static build-up before a big jolt causes damage. I realize it's not a direct comparison, but it's close.
Jets
As moving object, Jet aircraft are subject to kinetic charge accumulation. It's another highly technical subject - basically differebnt from sailboat masts, which (more) resemble land-based towers. Rather than comment beyond my expertise, I'll defer to the more knowledgable on this specific... Gord
As moving object, Jet aircraft are subject to kinetic charge accumulation. It's another highly technical subject - basically differebnt from sailboat masts, which (more) resemble land-based towers. Rather than comment beyond my expertise, I'll defer to the more knowledgable on this specific... Gord
Not so, Arlyn
ARLYN: I am on the side of rational judgement - not a "buy mine" self-interested point of view. Obviously, you didn’t read any of the references I listed (including a proponent of “dissipators”). You might also review "Professional Boatbuilder", issues 49 & 50. Were this a court case, the Judge would direct a verdict (against “dissipators”) for lack of evidence. Ion Diffuser (and the names change weekly) ads have presented the buyer with a moving target as to their claims. At one time they claimed to PREVENT lightning strikes (and even offered a guarantee - which they couldn’t honor), and more lately to reduce the likelihood of a strike. Likewise their theory of operation has changed - as each theory has (in turn) been discounted by Academics studying lightning phenomenon. The disparagement of Lightning Dissipation theory is virtually universal (not limited to Ewan Thompson, PhD - Florida Sea Grant); whereas these (various) dissipation theories are prounded only by suppliers of product (who obviously have a self-interest). There is a maxim that says - “extraordinary claims require extraordinary evidence”. It is incumbent upon the manufacturers of “dissipators” to support any claims for efficacy they make. They have failed to substantiate any claims. The researchers (with no evident self-interest), on the other hand present a preponderance of counter evidence. The jury is in - there is no reason to believe that “dissipators” work. Your second posting suggest that and “isolated” mast might best be protected with an arrestor. There is NO SUCH THING as an effectively isolated (against lightning) mast! SEE NORMAN’s POST !!! Your description of a welding cable “arrestor” is ludicrous. A Lightning Arrestor (Surge Suppressor, or Transient Voltage Sure Suppressor) is generally considered to be a device that prevents the peak voltage from going above a certain threshold such as plus-or-minus 200 volts. Semiconductor devices (that can conduct electricity under some conditions but not others) are used for this purpose. What you’ve described MIGHT be a sort of crude sort of “grounded choke” coil. Respectfully, Gord
ARLYN: I am on the side of rational judgement - not a "buy mine" self-interested point of view. Obviously, you didn’t read any of the references I listed (including a proponent of “dissipators”). You might also review "Professional Boatbuilder", issues 49 & 50. Were this a court case, the Judge would direct a verdict (against “dissipators”) for lack of evidence. Ion Diffuser (and the names change weekly) ads have presented the buyer with a moving target as to their claims. At one time they claimed to PREVENT lightning strikes (and even offered a guarantee - which they couldn’t honor), and more lately to reduce the likelihood of a strike. Likewise their theory of operation has changed - as each theory has (in turn) been discounted by Academics studying lightning phenomenon. The disparagement of Lightning Dissipation theory is virtually universal (not limited to Ewan Thompson, PhD - Florida Sea Grant); whereas these (various) dissipation theories are prounded only by suppliers of product (who obviously have a self-interest). There is a maxim that says - “extraordinary claims require extraordinary evidence”. It is incumbent upon the manufacturers of “dissipators” to support any claims for efficacy they make. They have failed to substantiate any claims. The researchers (with no evident self-interest), on the other hand present a preponderance of counter evidence. The jury is in - there is no reason to believe that “dissipators” work. Your second posting suggest that and “isolated” mast might best be protected with an arrestor. There is NO SUCH THING as an effectively isolated (against lightning) mast! SEE NORMAN’s POST !!! Your description of a welding cable “arrestor” is ludicrous. A Lightning Arrestor (Surge Suppressor, or Transient Voltage Sure Suppressor) is generally considered to be a device that prevents the peak voltage from going above a certain threshold such as plus-or-minus 200 volts. Semiconductor devices (that can conduct electricity under some conditions but not others) are used for this purpose. What you’ve described MIGHT be a sort of crude sort of “grounded choke” coil. Respectfully, Gord
So Gord, What would you do?
I have one of those lightning master disapators that came with my boat. In your judgement, would you just take the thing off? I always thought the thing looked phoney and have been concerned that it would do more harm than good. Reading Fred's post, it appears my fears may have validity. thanks Ward
I have one of those lightning master disapators that came with my boat. In your judgement, would you just take the thing off? I always thought the thing looked phoney and have been concerned that it would do more harm than good. Reading Fred's post, it appears my fears may have validity. thanks Ward
Andy, Those are for Somthing Else All Together
It is my understanding that the sticks are there to bleed off static electricity so that when the plane lands it does not zapp the crap out of the first person to touch the plane. Also to prevent a static charge from going through the electronics or any munitions loaded on the aircraft. It is amazing how small an electrical charge is needed to set off many of these things. My solution for dealing with lightning is: paid up insurance, not sailing in thunderstorms, and clean living.
It is my understanding that the sticks are there to bleed off static electricity so that when the plane lands it does not zapp the crap out of the first person to touch the plane. Also to prevent a static charge from going through the electronics or any munitions loaded on the aircraft. It is amazing how small an electrical charge is needed to set off many of these things. My solution for dealing with lightning is: paid up insurance, not sailing in thunderstorms, and clean living.
Gordon/Arlyn -- I have racked my brain over this
one for a while. I'm really not so sure of which side I fall. (Bond for lightning or not) One thing no one really did mention (and I think the facts do bear this out) is that if you do happen to be hit, having a properly grounded/bonded lightning system installed the damage to your boat and electronics will be greatly reduced. The quandry, which is not fully brought out (at least to my mind) is whether that a properly grounded/bonded lightning system increased the chance of being hit any. Initially one would think you are now creating an easier path to ground, but then why aren't the percentage of boats with bonding systems that are hit by lightning higher. I think the reality is lightning has travelled a few miles to find its home (ground) and a few feet at the end isn't going to change that any (whether bonded or not). Thats why you hear stories of bonded and non-bonded boats alike next to each other getting hit. I think lightning is an equal opportunity 'striker'. I am **not** sold on the efficacy of a diffusors But here is a very interesting discussion between the "experts" on lightning roda and dissiaptors" Very interesting and illuminating. Not all experts agree http://www.thomson.ece.ufl.edu/lightning/Moore%20on%20air%20terminals.htm Here are a few more detail articles writen by individuals http://www.lightningsafety.com/nlsi_lhm/magic.pdf http://www.lightningsafety.com/nlsi_lhm/charge_transfer.html And Here is a link to the site where the most research work is being done. http://www.ee.nmt.edu/~langmuir/ http://bat.nmt.edu/ Interesting stuff done here -- One **VERY** interesting point they are starting to see being backed up by real life studies, is that "pointy" end lightning rods are less likely to be "struck" than blunt end lightning rods which are next to them. Maybe this does lend to the "idea" (not reality) that these "Bottle brush" dissipators have merit, since they have lots of little pointy ends. Here are few sites from NOAA weather that has some good links on lightning etc. http://www.lightningsafety.noaa.gov/more.htm http://www.nssl.noaa.gov/researchitems/lightning.shtml
one for a while. I'm really not so sure of which side I fall. (Bond for lightning or not) One thing no one really did mention (and I think the facts do bear this out) is that if you do happen to be hit, having a properly grounded/bonded lightning system installed the damage to your boat and electronics will be greatly reduced. The quandry, which is not fully brought out (at least to my mind) is whether that a properly grounded/bonded lightning system increased the chance of being hit any. Initially one would think you are now creating an easier path to ground, but then why aren't the percentage of boats with bonding systems that are hit by lightning higher. I think the reality is lightning has travelled a few miles to find its home (ground) and a few feet at the end isn't going to change that any (whether bonded or not). Thats why you hear stories of bonded and non-bonded boats alike next to each other getting hit. I think lightning is an equal opportunity 'striker'. I am **not** sold on the efficacy of a diffusors But here is a very interesting discussion between the "experts" on lightning roda and dissiaptors" Very interesting and illuminating. Not all experts agree http://www.thomson.ece.ufl.edu/lightning/Moore%20on%20air%20terminals.htm Here are a few more detail articles writen by individuals http://www.lightningsafety.com/nlsi_lhm/magic.pdf http://www.lightningsafety.com/nlsi_lhm/charge_transfer.html And Here is a link to the site where the most research work is being done. http://www.ee.nmt.edu/~langmuir/ http://bat.nmt.edu/ Interesting stuff done here -- One **VERY** interesting point they are starting to see being backed up by real life studies, is that "pointy" end lightning rods are less likely to be "struck" than blunt end lightning rods which are next to them. Maybe this does lend to the "idea" (not reality) that these "Bottle brush" dissipators have merit, since they have lots of little pointy ends. Here are few sites from NOAA weather that has some good links on lightning etc. http://www.lightningsafety.noaa.gov/more.htm http://www.nssl.noaa.gov/researchitems/lightning.shtml
The researchers
quote: The researchers (with no evident self-interest), on the other hand present a preponderance of counter evidence. If Dr. Thomson is included in this group I'd have to say that someone who is a litigation expert witness for hire, who on a web site advocates liability, who has a business selling lightning protection, has a special interest. On top of that... his evidence for his theory that ungrounded mast are hit in the same or higher ratio than grounded mast is either misleading orindicates some poor logic. As for dissipation... here is a bit of anecdotal thought. Hams have always taken a few lightning strikes on their towers from time to time but when the 2 meter FM explosion of activity hit, Hams were eager to work the line of sight repeaters in various surrounding locations. To do this, they started putting vertical antennas as the top structure on their towers above their horizontal HF beams. Suddenly, they took lightning strikes in unprecedented numbers. Why? Because a horizontal beam lacks a single dispersion point that increases the odds that an attachment spark will be sent upward. Senior level engineers from Rockwell International and others... warned to make horizontal beams again the top most structure. Hams took that advice and removed the verticals (the ones not blown off) and strikes returned to previous rates. quote: There is NO SUCH THING as an effectively isolated (against lightning) mast! Thats true, but the same is true for a LPS. From the National Lightning Protection Institute, "LIGHTNING PROTECTION SYSTEMS PROVIDE LIMITED PROTECTION." What this means is that if an ungrounded mast reduces the propensity of a strike then that might be the best choice based on the realities that a strike is likely going to do damage even with a LPS and there just isn't any justification for fear mongering the issue. Even if lightning does hit an ungrounded sailboat, statistics bear out that it will in all likelyhood hit the mast anyway rather than a direct hit to someone aboard. What is very interesting in all this is that using the year 2000 for an example... only three fatalities in boats nationally and all three were in Florida. And, even then the statistics don't account for what kind of boat but even Dr Thomson admits that most fatalities and injuries caused by lightning happens in small open boats. My point is simply one of odds... and my comments are too those of us who have ungrounded mast (outboard motor) and sail on fresh water. If grounding increases the odds of being struck... then I'm not going there. So far, no one has offered any evidence that grounded and ungrounded mast are hit at the same ratio. Dr. Thomson claims to have... but his logic is very flawed. For those with an inboard...your likely grounded and if you have a mast mounted antenna... you've also got a lightning rod... I'd then install a LPS because your likely inviting a strike to hit because the system is in place to send attachment sparks. quote: Your description of a welding cable “arrestor” is ludicrous. Not a choke ... an air dielectric arrestor used to ensure that the mast stays isolated (ungrounded) and therefore not fed a supply of electrons to support an attachment spark. If I ground my ungrounded mast... I've very certainly provided an elevated ground compared to the water surface surrounding the boat. On the other hand, if the mast is ungrounded, the path might just appear to be farther through the mast than it is to the surrounding water. How can this be? Consider the dielectric properties of the hull and do the math. Sure, the strike can choose to hit the mast and then go airborn again at the base, and no doubt does often. On the other hand... a great many trailer sailors with ungrounded mast have experienced very near strikes. Why do they hit so close but yet not choose to hit the boat? When statistical data supports a theory that ungrounded mast are hit in equal ratios as grounded... or that grounded mast experience the same ratio of near strikes as ungrounded... then you've sold me... but that hasn't happened yet because neither side of this issue has collected enough data to yield clarity for a reasonable conclusion. What we do know is that grounded objects are favorites for lightning. Those in open areas, farmers working the ground with a tractor, heavy equipment operators, towers, buildings with electrical wiring and plumbing, and trees - all of which have in common that they are grounded. I think I'll take the hint and stay ungrounded.
quote: The researchers (with no evident self-interest), on the other hand present a preponderance of counter evidence. If Dr. Thomson is included in this group I'd have to say that someone who is a litigation expert witness for hire, who on a web site advocates liability, who has a business selling lightning protection, has a special interest. On top of that... his evidence for his theory that ungrounded mast are hit in the same or higher ratio than grounded mast is either misleading orindicates some poor logic. As for dissipation... here is a bit of anecdotal thought. Hams have always taken a few lightning strikes on their towers from time to time but when the 2 meter FM explosion of activity hit, Hams were eager to work the line of sight repeaters in various surrounding locations. To do this, they started putting vertical antennas as the top structure on their towers above their horizontal HF beams. Suddenly, they took lightning strikes in unprecedented numbers. Why? Because a horizontal beam lacks a single dispersion point that increases the odds that an attachment spark will be sent upward. Senior level engineers from Rockwell International and others... warned to make horizontal beams again the top most structure. Hams took that advice and removed the verticals (the ones not blown off) and strikes returned to previous rates. quote: There is NO SUCH THING as an effectively isolated (against lightning) mast! Thats true, but the same is true for a LPS. From the National Lightning Protection Institute, "LIGHTNING PROTECTION SYSTEMS PROVIDE LIMITED PROTECTION." What this means is that if an ungrounded mast reduces the propensity of a strike then that might be the best choice based on the realities that a strike is likely going to do damage even with a LPS and there just isn't any justification for fear mongering the issue. Even if lightning does hit an ungrounded sailboat, statistics bear out that it will in all likelyhood hit the mast anyway rather than a direct hit to someone aboard. What is very interesting in all this is that using the year 2000 for an example... only three fatalities in boats nationally and all three were in Florida. And, even then the statistics don't account for what kind of boat but even Dr Thomson admits that most fatalities and injuries caused by lightning happens in small open boats. My point is simply one of odds... and my comments are too those of us who have ungrounded mast (outboard motor) and sail on fresh water. If grounding increases the odds of being struck... then I'm not going there. So far, no one has offered any evidence that grounded and ungrounded mast are hit at the same ratio. Dr. Thomson claims to have... but his logic is very flawed. For those with an inboard...your likely grounded and if you have a mast mounted antenna... you've also got a lightning rod... I'd then install a LPS because your likely inviting a strike to hit because the system is in place to send attachment sparks. quote: Your description of a welding cable “arrestor” is ludicrous. Not a choke ... an air dielectric arrestor used to ensure that the mast stays isolated (ungrounded) and therefore not fed a supply of electrons to support an attachment spark. If I ground my ungrounded mast... I've very certainly provided an elevated ground compared to the water surface surrounding the boat. On the other hand, if the mast is ungrounded, the path might just appear to be farther through the mast than it is to the surrounding water. How can this be? Consider the dielectric properties of the hull and do the math. Sure, the strike can choose to hit the mast and then go airborn again at the base, and no doubt does often. On the other hand... a great many trailer sailors with ungrounded mast have experienced very near strikes. Why do they hit so close but yet not choose to hit the boat? When statistical data supports a theory that ungrounded mast are hit in equal ratios as grounded... or that grounded mast experience the same ratio of near strikes as ungrounded... then you've sold me... but that hasn't happened yet because neither side of this issue has collected enough data to yield clarity for a reasonable conclusion. What we do know is that grounded objects are favorites for lightning. Those in open areas, farmers working the ground with a tractor, heavy equipment operators, towers, buildings with electrical wiring and plumbing, and trees - all of which have in common that they are grounded. I think I'll take the hint and stay ungrounded.
Sorry Arlyn some of the statements warrant comment
1st) Your comment " On top of that... his evidence for his theory that ungrounded mast are hit in the same or higher ratio than grounded mast is either misleading or indicates some poor logic." Also "When statistical data supports a theory that ungrounded mast are hit in equal ratios as grounded... or that grounded mast experience the same ratio of near strikes as ungrounded... then you've sold me... but that hasn't happened yet because neither side of this issue has collected enough data to yield clarity for a reasonable conclusion" Fine. Granted. But then PLEASE show me 1 study (just one - I'm easy) that shows evidence otherwise -- I don't disagree with the theory you present. But until you have any hard data, then you are just a 'guy' speculating. Even the one desenting voice from the Univ Of Flor. does not show any overwhelming evidence , if you go by the numbers and the study the results are still too close to come to any conclusions. But I will grant you that I have seen flaws in his study. I have seen and answered your study -- At the time I wrote back to you that there were also some severe deficiencies in the questionere that would allow misguided assumptions. It was woefully inadequate in coming to any hard and fast assumptions in this area. We have to go with what we do have. At this point the studies show that the chance of a lightning strike hitting a bonded boat are no better or worse than unbonded. For every story that you hear about a bonded boat getting hit, there is another one with an unbonded boat (with a smaller mast, right next a bonded boat) getting hit. 2nd) " Even if lightning does hit an ungrounded sailboat, statistics bear out that it will in all likelyhood hit the mast anyway rather than a direct hit to someone aboard. " Granted -- but you conveniently failed to mention (and all the research and studies bear this out in very explicitely) is that if you do happen to be hit, having a properly grounded/bonded lightning system installed will mitigate and greatly reduce damage to your boat and electronics. Your claim above is great the people on board might not get hit, but that lightning will blow most of your electronics to dust & put 100 pin holes in your hull -- Sheez -- failed to mention that didn't you. If I'm sailing across the ocean and miles from land, I want whatever effects that lightning might have when it hits me reduced to a minimum. Isolation does not do that. I guess for a trailer sailor, your hypothesis has something, you can always just run home to port, assuming you are close to land. Let me add a twist to that, would you want your loved ones down below in the cabin when that lightning followed down the mast into the cabin looking for a place to exit and your boat wasn't bonded? Not me.
1st) Your comment " On top of that... his evidence for his theory that ungrounded mast are hit in the same or higher ratio than grounded mast is either misleading or indicates some poor logic." Also "When statistical data supports a theory that ungrounded mast are hit in equal ratios as grounded... or that grounded mast experience the same ratio of near strikes as ungrounded... then you've sold me... but that hasn't happened yet because neither side of this issue has collected enough data to yield clarity for a reasonable conclusion" Fine. Granted. But then PLEASE show me 1 study (just one - I'm easy) that shows evidence otherwise -- I don't disagree with the theory you present. But until you have any hard data, then you are just a 'guy' speculating. Even the one desenting voice from the Univ Of Flor. does not show any overwhelming evidence , if you go by the numbers and the study the results are still too close to come to any conclusions. But I will grant you that I have seen flaws in his study. I have seen and answered your study -- At the time I wrote back to you that there were also some severe deficiencies in the questionere that would allow misguided assumptions. It was woefully inadequate in coming to any hard and fast assumptions in this area. We have to go with what we do have. At this point the studies show that the chance of a lightning strike hitting a bonded boat are no better or worse than unbonded. For every story that you hear about a bonded boat getting hit, there is another one with an unbonded boat (with a smaller mast, right next a bonded boat) getting hit. 2nd) " Even if lightning does hit an ungrounded sailboat, statistics bear out that it will in all likelyhood hit the mast anyway rather than a direct hit to someone aboard. " Granted -- but you conveniently failed to mention (and all the research and studies bear this out in very explicitely) is that if you do happen to be hit, having a properly grounded/bonded lightning system installed will mitigate and greatly reduce damage to your boat and electronics. Your claim above is great the people on board might not get hit, but that lightning will blow most of your electronics to dust & put 100 pin holes in your hull -- Sheez -- failed to mention that didn't you. If I'm sailing across the ocean and miles from land, I want whatever effects that lightning might have when it hits me reduced to a minimum. Isolation does not do that. I guess for a trailer sailor, your hypothesis has something, you can always just run home to port, assuming you are close to land. Let me add a twist to that, would you want your loved ones down below in the cabin when that lightning followed down the mast into the cabin looking for a place to exit and your boat wasn't bonded? Not me.
Richard & Ward
Richard Marble & Ward Niffenegger both ask about "Bottle Brush Dissipators" (efficacious? & remove or not?). The short answers: I think I've answered Richard's query, in that I don't believe they are worth the money. I don't think they will do any harm, so would not suggest you remove an (already installed) dissipator. Regards, Gord
Richard Marble & Ward Niffenegger both ask about "Bottle Brush Dissipators" (efficacious? & remove or not?). The short answers: I think I've answered Richard's query, in that I don't believe they are worth the money. I don't think they will do any harm, so would not suggest you remove an (already installed) dissipator. Regards, Gord
Trailer Sailor Cruiser
Tom, Thomson asserts that ungrounded mast are hit in the same proportion as grounded based on his offering of reports from surveyors. He concludes that mast without a LPS system are ungrounded and those with are grounded. He then offers that more ungrounded mast are hit than are grounded. This is flawed logic because he does not account for the very strong possibilities for other reasons the mast would be grounded. Electrical lighting, instruements and antennas may in fact and probably do ground the mast on all boats equipped with an inboard. Its very likely that many if not most of the boats in his study were inboards which would mean that most of the boats shared the same quality of a grounded mast. His comparison is flawed and his conclusion is flawed and the tens of writers that lean on his flawed logic are echoing the same flaw. If we concluded that inboards have grounded mast and boats without auxilliaries have ungrounded, Boat US insurance claim numbers would suggest ungrounded mast are hit in one third the ratio of grounded mast. This is the single best statistic available that I know of. On my survey so far, of the 12 mast hits, 9 were grounded or should be considered grounded because they listed both an inboard and antenna on the mast. 3 were ungrounded. Grounded mast then were hit three times the rate of ungrounded. This figure matches identically the Boat US statistic. Certainly my study has no statistical basis yet... My goal was to get at least 100 reports before even considering it of worth. Half of my reports were of near misses and of those, twice as many near misses occured on ungrounded compared to grounded. Again... to few to draw conclusions... but if prelimary results hold, they may tell a story. There is no doubt that an adequate ground will mitigate damage if a strike happens. The word mitigate is interesting and hence the reason why I think if my chances of being struck are reduced by staying ungrounded, that it might be as good as a decision as providing what would be a half hearted attempt at grounding which might increase the liklihood of a strike. Again... the best evidence to me so far is that ungrounding does help the percentages. Saying this, I do think a lot of sailors think if they don't have an intentional lightning protection system, that they are ungrounded... this is not true. While far too simplistic, if you have an inboard, your probably grounded. I agree that your suggestions to add the salt water and others were pertinent and appreciated your input. btw...I did add the salt water question to the survey. My goal was to keep the survey limited to ten questions. I felt that near strikes deserved some attention because if there is a ratio disparity between near strikes... then that may tell us something about the mast ground / unground issue. Its true that my comments are driven by the fact that I'm a trailer sailor but I'm also a cruiser. Last year I wetted my hulls twice, once for a weekend overnight with the grandkids on the local lake and once for twenty four days of cruising on the Great Lakes which covered 800 miles and included two open water 90 mile crossings of Lake Huron and two 36 mile crossings between Michigan's lower peninsula an the North Channel. I am not hesitant about open water passages though I watch the weather window because my boat is a trailer sailor and thus subject to coastal cruising. Coastal defined by restricted to a weather window which most think to be 24-36 hours. You are right that my concern is relative to the mast ground / unground issue. If a mast is grounded and I'd assume that all will be on inboard equipped boats, then a LPS system is in order to provide an adequate conductive ground. My argument is somewhat a tangent issue where the prime issue for most is how to ground adequately. I really have not intended to weigh in on that other than to wholeheartedly agree to do it on boats that have grounded mast. quote: Let me add a twist to that, would you want your loved ones down below in the cabin when that lightning followed down the mast into the cabin looking for a place to exit and your boat wasn't bonded? Not me. I respect that... The problem is this, I sail on fresh water. The experts seem to be saying that to provide an adequate ground, I'd likely have to copper plate the majority of my wetted surface... unrealistic. And if an inadequate ground is more risky than remaining ungrounded... then I will take the risk. I could choose to not go sailing... but then I'd suffer a life without something I truly love to do. I could choose to do what most trailer sailors do and not cruise... but again, I don't much care for day sailing anymore... I love cruising. I can't afford a blue water boat and am landlocked any way... but a trailer sailor works for me. There are a fair number of trailer cruisers like me... should we try to emulate our blue water cousins or recognize our differences and make decisions according to our needs. I've heard the query tens of times, should I drop jumper cables into the water from my shrouds from people who think that they would feel better if they were doing something. I've not heard of one instance that jumper cables attracted a strike... so don't think it has proven to hurt and if it offers assurance... then well and fine. The big issue here is that out there running around are folks like Thomson who are purporting that I'm liable if I don't do something because he wants to make a living as an expert witness and has propelled himself to expert status with flawed logic. I'm simply saying that for blue water boats... if y'all want to consider yourself liable because you haven't provided a certified ground system... thats fine. But, I can see where that will go. Trailer sailors will get caught in the trap unless someone steps up to the plate and says... wait a minutes, ungrounded mast are different. Staying ungrounded may be just as or more prudent as trying to ground where it can't reasonably be done. Thomson has clearly said, that he considers an ungrounded mast to be a liability issue. I don't agree. In part because his logic is flawed. In part because the few good statistics we have are telling us otherwise. Just as you want to make the right decisions for your family on your blue water boat, I so to want to make the right decisions for mine on my trailer cruiser. I suffered a lightning strike in my ham shack.... a huge fireball exploded right above the console and burned my eye lashes. It happened shortly after installing a lightning rod (aka veritcal antenna) on top of my tower. Everything was disconnected. The tower was well grounded, the ham shack was grounded. Experts said, don't put a vertical (lightning rod) back on top and I've not been hit since. In twenty years, the only time the tower was hit...was shortly after installing the vertical and this story is repeated over and over again in the ham community. I suffered a near miss on my sailboat on an open water passage out of sight of land. The shock wave shook the boat it was so close. Experts say that the shock wave only travels a short distance of perhaps 40-60 ft. It was the only strike heard. Ten miles is the accepted distance for hearing thunder so it was the only strike in a twenty mile diameter and it hit 50 ft from the boat yet didn't hit the mast or boat....why not? Sorry, I gotta believe if I were grounded... it would have hit the mast. I hear what yor saying about the unpredictability and there certainly have been times when a shorter mast is hit in a marina with taller mast around. There might be explanations, there might not. I'm an advocate of gathering as much data about these kinds of strikes as possilbe. I think they would tell a story and in my opinion it would be a story about percentages rather than hard rules.
Tom, Thomson asserts that ungrounded mast are hit in the same proportion as grounded based on his offering of reports from surveyors. He concludes that mast without a LPS system are ungrounded and those with are grounded. He then offers that more ungrounded mast are hit than are grounded. This is flawed logic because he does not account for the very strong possibilities for other reasons the mast would be grounded. Electrical lighting, instruements and antennas may in fact and probably do ground the mast on all boats equipped with an inboard. Its very likely that many if not most of the boats in his study were inboards which would mean that most of the boats shared the same quality of a grounded mast. His comparison is flawed and his conclusion is flawed and the tens of writers that lean on his flawed logic are echoing the same flaw. If we concluded that inboards have grounded mast and boats without auxilliaries have ungrounded, Boat US insurance claim numbers would suggest ungrounded mast are hit in one third the ratio of grounded mast. This is the single best statistic available that I know of. On my survey so far, of the 12 mast hits, 9 were grounded or should be considered grounded because they listed both an inboard and antenna on the mast. 3 were ungrounded. Grounded mast then were hit three times the rate of ungrounded. This figure matches identically the Boat US statistic. Certainly my study has no statistical basis yet... My goal was to get at least 100 reports before even considering it of worth. Half of my reports were of near misses and of those, twice as many near misses occured on ungrounded compared to grounded. Again... to few to draw conclusions... but if prelimary results hold, they may tell a story. There is no doubt that an adequate ground will mitigate damage if a strike happens. The word mitigate is interesting and hence the reason why I think if my chances of being struck are reduced by staying ungrounded, that it might be as good as a decision as providing what would be a half hearted attempt at grounding which might increase the liklihood of a strike. Again... the best evidence to me so far is that ungrounding does help the percentages. Saying this, I do think a lot of sailors think if they don't have an intentional lightning protection system, that they are ungrounded... this is not true. While far too simplistic, if you have an inboard, your probably grounded. I agree that your suggestions to add the salt water and others were pertinent and appreciated your input. btw...I did add the salt water question to the survey. My goal was to keep the survey limited to ten questions. I felt that near strikes deserved some attention because if there is a ratio disparity between near strikes... then that may tell us something about the mast ground / unground issue. Its true that my comments are driven by the fact that I'm a trailer sailor but I'm also a cruiser. Last year I wetted my hulls twice, once for a weekend overnight with the grandkids on the local lake and once for twenty four days of cruising on the Great Lakes which covered 800 miles and included two open water 90 mile crossings of Lake Huron and two 36 mile crossings between Michigan's lower peninsula an the North Channel. I am not hesitant about open water passages though I watch the weather window because my boat is a trailer sailor and thus subject to coastal cruising. Coastal defined by restricted to a weather window which most think to be 24-36 hours. You are right that my concern is relative to the mast ground / unground issue. If a mast is grounded and I'd assume that all will be on inboard equipped boats, then a LPS system is in order to provide an adequate conductive ground. My argument is somewhat a tangent issue where the prime issue for most is how to ground adequately. I really have not intended to weigh in on that other than to wholeheartedly agree to do it on boats that have grounded mast. quote: Let me add a twist to that, would you want your loved ones down below in the cabin when that lightning followed down the mast into the cabin looking for a place to exit and your boat wasn't bonded? Not me. I respect that... The problem is this, I sail on fresh water. The experts seem to be saying that to provide an adequate ground, I'd likely have to copper plate the majority of my wetted surface... unrealistic. And if an inadequate ground is more risky than remaining ungrounded... then I will take the risk. I could choose to not go sailing... but then I'd suffer a life without something I truly love to do. I could choose to do what most trailer sailors do and not cruise... but again, I don't much care for day sailing anymore... I love cruising. I can't afford a blue water boat and am landlocked any way... but a trailer sailor works for me. There are a fair number of trailer cruisers like me... should we try to emulate our blue water cousins or recognize our differences and make decisions according to our needs. I've heard the query tens of times, should I drop jumper cables into the water from my shrouds from people who think that they would feel better if they were doing something. I've not heard of one instance that jumper cables attracted a strike... so don't think it has proven to hurt and if it offers assurance... then well and fine. The big issue here is that out there running around are folks like Thomson who are purporting that I'm liable if I don't do something because he wants to make a living as an expert witness and has propelled himself to expert status with flawed logic. I'm simply saying that for blue water boats... if y'all want to consider yourself liable because you haven't provided a certified ground system... thats fine. But, I can see where that will go. Trailer sailors will get caught in the trap unless someone steps up to the plate and says... wait a minutes, ungrounded mast are different. Staying ungrounded may be just as or more prudent as trying to ground where it can't reasonably be done. Thomson has clearly said, that he considers an ungrounded mast to be a liability issue. I don't agree. In part because his logic is flawed. In part because the few good statistics we have are telling us otherwise. Just as you want to make the right decisions for your family on your blue water boat, I so to want to make the right decisions for mine on my trailer cruiser. I suffered a lightning strike in my ham shack.... a huge fireball exploded right above the console and burned my eye lashes. It happened shortly after installing a lightning rod (aka veritcal antenna) on top of my tower. Everything was disconnected. The tower was well grounded, the ham shack was grounded. Experts said, don't put a vertical (lightning rod) back on top and I've not been hit since. In twenty years, the only time the tower was hit...was shortly after installing the vertical and this story is repeated over and over again in the ham community. I suffered a near miss on my sailboat on an open water passage out of sight of land. The shock wave shook the boat it was so close. Experts say that the shock wave only travels a short distance of perhaps 40-60 ft. It was the only strike heard. Ten miles is the accepted distance for hearing thunder so it was the only strike in a twenty mile diameter and it hit 50 ft from the boat yet didn't hit the mast or boat....why not? Sorry, I gotta believe if I were grounded... it would have hit the mast. I hear what yor saying about the unpredictability and there certainly have been times when a shorter mast is hit in a marina with taller mast around. There might be explanations, there might not. I'm an advocate of gathering as much data about these kinds of strikes as possilbe. I think they would tell a story and in my opinion it would be a story about percentages rather than hard rules.
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