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lightning advice

4K views 38 replies 12 participants last post by  lancelot9898 
#1 ·
Building boat. Although it has a high aspect,bulbed fin keel the keel is fully encapsulated in glass. Going to spent summers in New England ( low strike area) and USVI area winters (high strike area). Don't care about electronics so much ( insurance, boat already set up to ABYC rules to decrease side flashes) but do care about sinking. So far interested in Ewan's system form Marine Lightning but too many holes in the boat, major expense, and some fittings are marelon which I don't trust. Other is a grounding plate from Ward's in Florida. Everything solid bronze. Both give the "adequate" area by ABYC but Ewan's has more "edge" being a long (12') strip. Builder is putting heavy wire from shrouds/chainplates and mast to central point during construction.
? Any body have experince with either system or suggestion for another vendor.
? Has anybody had issues with electrolysis. Tying aluminum ( mast), stainless ( riggging )and bronze/copper ( grounding) together. Told can't zinc system as grounding plate/ strip must be left bare or will foul if zinc'd system.
?anybody use a knife switch or other device to leave grounding plate disconnected except when in "at risk" situation.
Any help or thoughts greatly appreciated.
thanks
 
#2 ·
Some fellow sailors in our harbor have tied the rig together with heavy gauge ground wires, then permanently fastened them to a heavy wire (1/0 or more) that has at least a foot of insulation stripped on the bottom end, and hung that wire over the stern into the drink. Probably not ABYC certified, but seems logical and practical (OK - cheap!). Regarding your systems - I doubt very much that there should be ANY "knife switch" in the circuit - a lightning strike will fry just about any switch, then you have nothing. Curious to see what others come up with. . . . ?
 
#3 ·
you may want to do some further research, there is a lot here and other sites. Some is rubbish (ie wrapping a chain around the mast and dropping the other end overboard) and some has merit, although lightning AKA mother nature will show you those shortcomings. Some of the radio communication and tower manufacturer sites will provide some more realistic mitigation thoughts.

Unless you are having the builder take the absolute shortest path from the mast and plates, via at least a 1/0 copper cable, to the keel with NO mechanical connections....lightning will find the shortest path, or jump to ground.

The idea of "attaching" (anything mechanical) the stuff to a cable and dropping the end in the water is absurd if you think lightning will follow the path YOU deem. Not going to happen. Even cadwelds and welded connections will blow apart when a strike occurs.

Your best bet is to avoid the strike, good insurance and luck. You are creating a boat that will have zinc/bonding/ground issues. Stick with ABYC.

As to electolysis, even a poorly designed ground plate or improperly installed and grounded can cause issues tough to find. Read up on ground loops, potential to ground, measuring leakage, etc.

YMMV
 
#4 ·
Agree 100% with kd3pc. After a direct strike while sailing I spent a lot of time researching the subject. I have come to the conclusion the only thing one can do is avoid electrical storms completely (impractical) or prayer (should have thought of this one before being hit). Fifteen years after the strike I am still extremely scared of lightning although, funnily enough, I gave it very little thought before being struck. As for hanging stuff over the side, that's ludicrous.
 
#5 ·
Any thoughts of directing 2 million volts is really ludicrous. It will find its shortest way out when it finds it way in wether a direct hoit, or a side swipe. The best thing to do is ro rey and give it some easy pathways like a plate on the humm directly wired with 1 gauges wire, but the truth be told as ataed above is to keep the thru hulls safe, have good insurance, and try to mitigate as much as possible the area you are in when the storm occurs.

We were side struck this sumer in Back Creek on a morring Annapolis surrounded by over 900 masts, By no means were we the tallest or isolated.
In our strike the lightening was traced to have it the water tower on the land 200 yards from us, comethrough the water, up the prop shaft and dyna plate and entered the electrical panel through the ground to the engine. It fused the engine panel ( engine was not affected), blew up most of the elctroinics ( even though many were off and disconnected), was very discriminating ( took out the white LED while leavung the eds alone on the same fixtures), left the radar and radar pole on the stern unscathed whhile getting the chartplotter. It exited the boat up the mast and jumped masts to the boat morred next to as as wa seen by the person on that boat. Yes we had a diffuser on top of the mast which ws blown off along with the windex.

preventable.....impossible...cone of protection...in your dreams...following prrescribed path....had its own mind and direction.

Dave
 
#6 ·
from what research I've done seems diffusers are not likely to be effective. ?still wondering if anybody has placed either the Ward ground plate or the Marine Lightning system on their boat and at their experience was with it.
 
#7 · (Edited by Moderator)
Grounding systems do help minimise the damage from a lightning strike. They are especially effective in reducing in catastrophic damage that sinks boats.
There is no risk of electrolysis problems despite the dissimilar metals. The metals are not immersed in an electrolyte. The only exception is a localised reaction around the aluminium / copper connection is if gets wet. So try and keep it dry.

Breaking the connection to the underwater plate will not make any difference to the risk of corrosion, but will reduce, or disable the lightning protection, so this is a bad idea.
 
#10 ·
Grounding systems do help minimise the damage from a lightning strike. They are especially effective in reducing in catastrophic damage that sinks boats.
There is no risk of electrolysis problems despite the dissimilar metals. The metals are not immersed in an electrolyte. The only exception is a localised reaction around the aluminium / copper connection is if gets wet. So try and keep it dry.

Breaking the connection to the underwater plate will not make any difference to the risk of corrosion, but will reduce, or disable the lightning protection, so this is a bad idea.
Can you give me some actual data. Tests? not just hypothesis or ligic, actual real workd tests?
 
#11 · (Edited by Moderator)
Having routinely worked with multi-million volt potentials, I disagree with some advice given here. One can minimize the probability of the strike going thru certain paths by offering a much better path and eliminating paths that you do not desire.
Most effective would be a very good lightning ground.

Shameless commercial plug:

My new company is now selling a lightning ground
Can you give me some actual data. Tests? not just hypothesis or ligic, actual real world tests?
 
#13 ·
not to quibble, but if you are sealing the mast against corrosion, how then are you going to:

" It carries a #4 tinned Ancor cable with a welding clamp to attach to the boat. It should attach to mast at the boom level by twisting to get a good connection thru the oxidized aluminum."

I am missing something with these two?
 
#14 ·
Appreciate the input. Spent time studying to be an e.e. at columbia u. before pursuing my ultimate career path - have some basic understanding of the engineering concepts. Appreciate comment about galvanic corrosion/elctrolysis. Appreciate kd3pc's posts as well. Surprising there is so little hard science and data about this issue. CE/ABYC rules seem aimed at preventing side flashes. Still wonder with encapsulated keel why it doesn't make sense to provide a low impedance, non ( or less) destructive pathway. Care about not having holes burnt thru the boat. care less about the e/m pulse destroying electronics. seems virtually all sites/articles I could find to date suggest with ground slightly higher chance of getting hit but much lower chance of sinking. Thought that came from pooled insurance data. Still will ask insurance vendor before installation. thanks for the idea kd3pc
 
#15 ·
Exactly how would one go about such testing? With lightning "diverters", it was sorta like saying they were also Elephant repellers until the escaped circus elephant jumped onto the boat with one. In a normal marina situation, the average boats strike probability is low..........unless you happen to be the isolated high mast.
 
#16 ·
No silly, do be so condescending

I meant things like, is there an insurance discount on boats with certain protections installed. Their data would indicate a preference as they would pay less insurance claims to boats with lightning prevention . Do you knw any company which does this?

Surely you mut have some concrete evidence of benefits other than you words that adding some system to a boat for hundreds, maybe thousands of dollars will have any difference at all.

I can put alligator clips on by shrouds and run a 1 wire into the water for pennies. Do you any scientific data or proof you system or "invention" is any better.

Short of any data or proof there are many snake oil salesmen that will sell you lots of their own theories to make money..

BTW aren't their rules on posting Sailnet against selling services or products. Even if you identify yourself, I don't think posts are an appropriate place to do this.
 
#17 ·
from what I can gather.
risk ~ 4 per thousand per year. higher FLA carribean lower NE
double risk for multi hulls
no good statistics for sinking with solid glass v cored v wood v carbon fibre but consensus extremely low for metal hulls.
If grounded and in salt water ~12' of "edge" required ( theoretical not backed by fact). Higher if in fresh.

Boat is in construction phase where installation at this point would be easier/cheaper. Still very confused. Will hold off untl I have more concrete knowledge. Thanks for all the opinions given but think to date they are just that- opinions. Have calls into certified marine elctricians and await replies. Perhaps will post when I have some facts to offer the group. Tx. for your input.
 
#18 ·
I am enjoying reading you experts discuss this.
As one that is not educated in the field, Do you mind if I ask a question?

By providing as easier path, are you not inviting a strike?
 
#25 ·
Another expert is Roger R. Block, co-founder of PolyPhaser Corporation, who has done a great deal of work protecting very expensive and one-off gear for the military and three letter initial companies inside the beltway. Extensive testing and validation and his works are available on the net. He has retired for the most part, but his devices and protection plans are second to none.

YMMV
 
#24 ·
Lightning is unpredictable, but still follows the laws of physics. If you can provide a good straight low resistance path to ground there is a good chance this is where the pulse will go.
This prevents the most severe damage which can occur when the energy exits the hull via a metal fitting such a seacock or chainplate. In the former case the reasonable chance the boat will sink in the later that the mast will fall down.

Grounding is not a guarantee that this is where the energy will go, but with a well made ground system it there is a very good chance that is where all, or most of the energy will be diverted to.

Grounding is best defence you have. It significantly reduces damage, particularly the severe damage that can mean loss of the vessel and / or lives.

However it does not:
Significantly reduce the chance of a strike
Mean you will have no damage
Guarantee you won't suffer severe damage.
 
#29 ·
This prevents the most severe damage which can occur when the energy exits the hull via a metal fitting such a seacock or chainplate. In the former case the reasonable chance the boat will sink in the later that the mast will fall down.
So what is your system on your boat other than a ground plate and an egine ground?

Grounding is not a guarantee that this is where the energy will go, but with a well made ground system it there is a very good chance that is where all, or most of the energy will be diverted to.
This is saying nothing saying I am not sure where the energy will go, but if it there is a ground system there is a good chance where the energy will go but maybe n ot all of it. Not a scientific or even a reassuring statement

Grounding is best defence you have. It significantly reduces damage, particularly the severe damage that can mean loss of the vessel and / or lives.
No its the only defense you have and the rest of the statement isnt true as you cant evebn gaurentee thats where the enrgy wil go. And where does this statement about loss of lives come from. Best way to prevent that is to be off the boat....not grounded.

Come on now, I can undertand the physics of lightening like most can. I can read the same experts. Coomon sense tells me it will search for the path of lerast resisitance or shortest path and thatits important to provide it with one or it will make one.

Common sense also tells me that people who try and make thousands of dollars off of this fear when they cannot prove or will not gaurentee their expensive products work are a sham.

These statements are a false sense of secutity when there is not gaurentees that your theory will work. It allows the snake oil salesman to create all sorts of diffusers and bonding/ grounding systems which cost thousands when there is no proof or gaurentee. Even the insurance companies see no value in this pr they wouild give people discounts. Its sheer speculation

The best you can do is ground evrything to a plate, give it a path...something which doesnt cost a lot of money and pray the lightning travels that path and doesnt seek an alternative.
 
#31 · (Edited)
Interesting discussion. Here is my experience. Anecdotal data a n of 1.

I was sailing my CS36 Merlin on Lake Ontario, about seven miles offshore headed back to Toronto. Keel stepped mast, mast shoe bonded to Hydrokeel wing keel (lead) with large guage wire connected to shoe and a keel bolt. Through hulls are not bonded. All bronze.

Saw really bad (worse I've seen) electrical storm approaching. When lightning struck the water ahead on my port bow, then starboard bow, started motor, put handheld vhf in my foul weather gear pocket, got position from GPS, wrote it on a piece of paper and tucked that in my pocket too. Wind died, torrential rain.

BANG! I remember a sizzling sound, that was all my masthead stuff hitting the water just behind me. Guess it was red hot. Autopilot failed. Put on wheel brake and took hands off wheel. Called Canadian Coast Guard on handheld, reported position and having been struck, said I was going down below to check for damage and would report back in ten minutes. They said they would call SAR in Trenton and if I did not report back they would be out.

Checked boat for water. None. All instruments out, lights out, vhf out, alternator shot (no engine instruments). Some led's on electrical panel out. Oddly enough the Garmin GPS (a small Garmin 64?, not grounded) was still working. Called CG, reported situation, said I was continuing to Toronto (about 70 miles more) and would report every half hour but turning off handheld to conserve battery. They informed me that SAR had told them that damage might not be readily apparent such as keel bolts failing. I said thanks. :) If I did not report every half hour SAR would be out. We went another hour through the electrical storm, making slight corrections to the course but with wheel brake on and hands off. Got back to Toronto. Thanked CG.

Hauled the boat a day or two later. There was "treeing" (electrical burn marks in a very unique pattern) at every through hull and on the rudder at the gudgeon. The charge had gone throughout the boat. From stem to stern. No structural damage. Mast was pulled. Headsail showed slight burning at the foil. The headsail was a North with a zippered sleeve over the foil. (Sometimes the foil sections fuse together).

Replaced all instruments, alternator. Corrected magnetic compass. About $20K.
 
#34 ·
Some good info here. issue remains absence of fact as it relates to sailboats. However significantly more info and additional avenues to research posited since my last post. thank you. Orginal question was comparing simple ground plate from Ward's to groundng strip ( and other measures) from Marine Lightning.Still very interested in discussion of orginal question if possible.Tenor of discussion here would seem to favor simple solid ground plate. As said keel bolts not an option. Been told layered plates should be avoided as likely to explode as water turns to steam as plate heats. Devices to dissipate charge likely to be inadequate in this application. More likely to have some marginal effect in solute ( water) than air ( mast head). However again no empiric evidence of benefit to sailboats. Will tell builder to put in wire runs from shrouds to foot of mast/bilge area but not connect them until I get further concrete data or I am convinced it does not exist. Land is not a conducting solute of similar magnitude as seawater. Buildngs may have the high impedances a glass hull has but not the low impedance masts/rigging etc inbedded in them and sticking out of them. Transmitter and electrical towers are metal structures in their entirety. Physics must be different for particulars of sailboats. tx. again.
 
#38 ·
Hi Maine,

You mentioned that for an encapsulated keel with a keel step mast that you would mount a long copper bar stock with a lot of edge surface. Not sure just how you run that wire from the keel step to that bar stock. Also everything on my boat is bonded from the keel step to the thru hulls to the keel bolt of the encapsulted keel and etc. Never did feel right about that wire going to the iron ballast in the encapsulated keel in that there would seem to be a possiblity that the energy could go directly from the encapsulated iron to the water through the fiberglass possibly sinking the boat.
 
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