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Otter
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Okay so my boat splashed today ( Santana 2023 ) and for the first time I'm keeping her at an actual marina vs a private slip I've had for years. Since I plan in spending a lot of time on her even if it's just at the dock I'm just wondering about lighting and complacency I guess. I've been out sailing in storms but that wasn't by choice per say. There are no electronics besides nav lights. So my question is, should I just kick back and relax or do anything preventative while in the slip? I only use the shore power while on board when using the computer or charging the battery. My old slip I wasn't able to really just relax on board. Was a get in and go so the other homeowners don't get angry kinda place.Thanks in advance.
 

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snake charmer, cat herder
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sailed gom with a friend onhis boat. yes some electronix, solar and wind gen. we did not die even tho we sailed fo r 10 1/2 mpnths in lugtning. his neighbor, onthe other hand, hhas suffered 2 hits in 4 yrs in slidell louisiana.... a tthe dock. second one was fatal to boat.
i would much rather be sailing. i wear rubber suit, crocs, gloves and a anti zap cat hat. (that would be my live gato, bubba.)
 

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I hear that cats are good conductors of electricity. Their goes up when that happens and u can see them in a X ray mode
 

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When we drop our pole this winter we will be installing a rod on the foremast. Its great insurance. Its also debatable if they work, and also if they prevent damage. We will however install one, and unplug and disconnect everything in a bad storm.
Mitigating lightning damage can get pretty technical: just check Marine Lightning Protection Inc. for some background information from one of the world leaders in this area. The bottom line for most of us is that we won't be going to the the trouble and expense required to implement a sophisticated lightning protection system.

That said, you can take some simpler measures to reduce your risk of damage and injury. If you have an aluminum mast, you can install a thru-hull ground plate, such as a Dynaplate that is connected with a heavy gauge (#8 or heavier) wire to your mast. You might also connect your chainplates to the Dynaplate as well. IMHO, you don't need a lightning rod on top of your big lightning rod (the aluminum mast itself.) Your mast will provide a "cone of protection" somewhat greater than 90 degrees, such that any lightning that would have struck within the protected area is more likely to attach to your mast.

The the larger "cone of protection" (based on mast height) explains why there is less personal injury from lightning on sailboats than on powerboats.

Unplugging and otherwise disconnecting your electronics can't hurt, but it is not likely to do much good in a direct strike or a strong side strike. If you have an oven onboard, you might stow your detachable electronics there during an electrical storm to reduce your risk of damage, but even that is not an iron-clad guarantee. Likewise, wrapping your handheld VHF, GPS, cell phone, etc. in aluminum foil is not a guarantee, but I feel better when I do this during an electrical storm.

After 2 strikes in 10 years and losing all my electronics in both events, my strategy is to maintain dead reckoning in the background while my electronics are functioning. I keep paper charts onboard and keep my binnacle compass in good repair. Most of all, I keep a proper insurance policy that covers replacement cost (i.e., no depreciation) within an agreed value limit.

BTW, this topic has been covered in other threads.
 

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Noah's Bosun
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236 Posts
My $0.02 for what it's worth...

Have always run an external ground plate connected to the mast as suggested by "fallard". The old Tripp sloop had a net air draft of 60' and never got hit once in 25 yrs. Might just be luck, but have been in a marina where shorter sticks got zapped but not the Escape.

One of the points of grounding the stick is to dissipate any "potential difference" between the boat and the storm clouds. Mounting a "pincushion" type airterminal (allegedly) increases the effect. I have always had one, and while I have seen it glowing like a neon tube in a bad storm, still have not got zapped (crosses fingers).

And now a completely new worry to keep you awake at night. Buddy of mine got his boat zapped last summer while it was up on the stands in the boat yard.... Never thought of that one before. Blew all the fairing compound out of the keel/hull joint (moisture flashing to steam?) when it hit as well as the usual strike damage to electronics. He now has a #4 cable run from the stick to a ground stake whenever he is on the hill.
 

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Super Moderator
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6,804 Posts
Are you trying to tell me that your electronics that were not plugged in were destroyed?
I have a hard time believing that the very weak EMP force destroys things in a lightning strike.
I do lightning damage repair and estimates and work closely with owners so they get a fair deal from insurance companies who send surveyors who know nothing about lightning damage. I can assure you that items not plugged in get fried with some decent frequency.

When our boat was hit back in 2010 this was our not plugged in but fried list:

*HP Laptop Computer - On nav desk unplugged but battery in it. Was in "sleep mode". Motherboard was replaced.

*Garmin GPS-MAP 176 - In nav desk unplugged but batteries in it. Garmin was no longer repairing these.

*Garmin 76 Hand Held - In waterproof dinghy bag sitting on settee. Batteries were in it. Had to buy a new one.

*Magellan HH GPS - In ditch bag wrapped in tin foil and inside a Ziplock with a desiccant pack. No batteries installed. It booted once for about 10 seconds then the screen went blank and it never booted again.

*EPIRB - Was inoperable in test mode and sent off and repaired. Had just had new factory installed batteries the previous year.

*iPod - In nav desk unplugged. Bought new...
 

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Schooner Captain
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hmmm, interesting. Magnetic shielding may be in order.
Sorry I am a Physical chemist, lightning is not my specialty.
That being said. Aluminum foil will not protect anything. Aluminum foil (in case you didnt know) Is not affected in any significant way by a magnet. A little know fact is this also applies to tin. They are in fact paramagnetic, but so lightly so they will not provide any sort of protection from a magnetic field.
Building a magnetic shield for your devices may be in order if you will be in a high strike area then. will your oven work? not if it has a window. A steel box with closing door, or a gun safe, should provide your electronics with all the protection they need to survive the EMP of a strike.
 

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Super Moderator
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hmmm, interesting. Magnetic shielding may be in order.
Sorry I am a Physical chemist, lightning is not my specialty.
That being said. Aluminum foil will not protect anything. Aluminum foil (in case you didnt know) Is not affected in any significant way by a magnet. A little know fact is this also applies to tin. They are in fact paramagnetic, but so lightly so they will not provide any sort of protection from a magnetic field.
Building a magnetic shield for your devices may be in order if you will be in a high strike area then. will your oven work? not if it has a window. A steel box with closing door, or a gun safe, should provide your electronics with all the protection they need to survive the EMP of a strike.
I now use an Army box that I bought surplus... We will see how it works if there is a next strike... ;)

The best protection for lightning is a good insurance policy!!!!
 

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Insurance... Its $3500 for our boat. that buys a lot of electronics. thou we are looking at a windvane now. those do not suffer damage from an EMP.
Our strike was about 24k in damage and we suffered ZERO hull damage. We pay $800.00 per year in insurance.... It will take the insurance company years to recoup our strike...

Most strikes I see are in the 8k to 30k range... I worked on a small sub 30' Ericson last summer in Portland and the insurance claim on that one was 8.5k..... I had a J-42 last summer that was 32k....

Lightning strikes are not just about electronics. Anyone who thinks they are should consider some serous lightning bonding to help minimize hull damage...

Lightning quite often makes holes in boats when it can't find a decent low resistance path to divert some of the force..... Boats sink from lightning strikes. Had a high dollar center console three years ago that sank due to lightning. It was a 6 figure boat only two years old... Boat was a total loss. Electronics are of minimal concern when that happens....;)
 

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Are you trying to tell me that your electronics that were not plugged in were destroyed?
I have a hard time believing that the very weak EMP force destroys things in a lightning strike.
In 2000, my boat was on the hard when a bolt struck 50-75' away, according to an eyewitness. My autohelm wheel pilot control head was completely detached and sitting on a shelf below. It didn't work after the strike and neither did anything with a semiconductor--electronics, alternator, battery isolator diodes, etc.

Note that all of the breakers in my panel were in the "off" position. Still, the inline fuses to my VHF looked like popped flashbulbs. "Weak EMP force"? I don't think so. I had a discussion with Ewen Thomson about EMP after that event. We wouldn't rule out a side discharge, but there was no physical evidence of high currents, as was the case in the direct hit my boat took in 2010, when my mast ground did its job.

As others have said, a good grounding system will reduce the risk of perforating your hull in a direct strike, so its not just about the electronics.

Regarding the "$3500...buys a lot of electronics", my 2010 strike at the dock resulted in an insurance settlement 10x that! The 2000 indirect strike resulted in a settlement somewhere around $22,000. My annual premium is about $1300, which is about $200 more than a quote I got that would have depreciated my electronics. I'll be keeping the more expensive policy!
 

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I believe it is a mistake to associate indirect lightning damage to EMP.

The bolt of lightning you see is the super condensed plasma arc of the strike- the "visible center" where current is highest. That bright jagged line is not the whole of the current flow. It is just the really hot part that you can see. Anything in the surrounding area is being zapped, too- only the amperage drops off quickly the farther you get from the center "visible" current. In most lightning strikes, you have no idea where the actual strike occurred other than seeing where the damage is. If nothing is burned and charred then you surmise where the current originated by tracing the path of ruined equipment or material.

All EMF is a field of varying density, and this field surrounds all current flow and moves in a circular direction in relation to the current. (right hand rule... for the geeks among us)

EMP is pulse. EMP's relationship to lightning is debatable, but one wouldn't know that from reading sales literature for lighting arresting gear. The effects can be very similar (induced current in electrical circuits), so if one decides to guard against the effects of EMP then who can blame them. But there are more differences than similarities. In the big scheme of things, the primary concern with lightning protection is to eliminate potential voltage between your boat and the surrounding area. In other words, don't be the big Positive in a field of Negative. Bonding and Grounding to make your boat look like the water is the highest priority.

Like everything else, it's all about magnitude. All lightning strikes aren't equal. A weak strike near your boat may not have much affect if your boat isn't at a different electrical potential than the strike point, because there won't be much induced current. A powerful hit anywhere in the area is going to sufficiently change the charge of the strike area enough that you will be at a relative different potential than you were before- and that difference in potential is what then causes current flow. So, in other words- if the strike is sufficiently powerful and/or close, then all bets are off anyway. The best you can do is the best you can do.
 

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A lot of the methodology of lightning prevention and protection has apparently changed over the years and continues to evolve. Here's some of the 'latest' thinking from the nationally renown & former FSU 'lightning guru': Marine Lightning Protection Inc. ..... enhanced interconnected electrical 'bonding' (ie. "Faraday Cage") of the boat that is allowed/designed to discharge lightning AT the waterline to the SURFACE of the water.

Ive begun to notice more and more of these 'waterline discharge electrodes' (Side-arc™ electrodes) on mega-yachts.
They're also seemingly more and more installing *Lightning clamping suppressors* for electronics ...
Transorb or TVS (transient voltage suppression), similar to what is found on large scale electrical distribution grids - an electrical 'clamp' that is intended to help instantly shut down 'spikes' in the power supply circuitry.
 

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Our strike was about 24k in damage and we suffered ZERO hull damage. We pay $800.00 per year in insurance.... It will take the insurance company years to recoup our strike...

Most strikes I see are in the 8k to 30k range... I worked on a small sub 30' Ericson last summer in Portland and the insurance claim on that one was 8.5k..... I had a J-42 last summer that was 32k....

Lightning strikes are not just about electronics. Anyone who thinks they are should consider some serous lightning bonding to help minimize hull damage...

Lightning quite often makes holes in boats when it can't find a decent low resistance path to divert some of the force..... Boats sink from lightning strikes. Had a high dollar center console three years ago that sank due to lightning. It was a 6 figure boat only two years old... Boat was a total loss. Electronics are of minimal concern when that happens....;)
A boat in my marina on a mooring was 'hit' by an apparent 'high amperage event'. The result was that the hull was destroyed (total loss) .., not by a big hole, per se; but, has literally MILLIONS of weep holes in the hole structure - the boat literally 'sweated' itself to sinking after the strike, millions of 'droplets' of seawater permeating through the laminate to the inside of the hull.
 

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Over Hill Sailing Club
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I use an old heavy duty flat metal box that a long ago-dead recip saw came in to act as a Faraday enclosure. At least it may protect small emergency comm. electronics and a small computer. The EPIRB will also fit in it. When lightning is in the area I stow the small electronics (computer, h/h radio, h/h/gps, cell phone, and other things) in it, wrapped in pieces of 6mil poly. I understand that a metal box only works if the devices are completely insulated from the sides.
 

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I believe it is a mistake to associate indirect lightning damage to EMP.

The bolt of lightning you see is the super condensed plasma arc of the strike- the "visible center" where current is highest. That bright jagged line is not the whole of the current flow. It is just the really hot part that you can see. Anything in the surrounding area is being zapped, too- only the amperage drops off quickly the farther you get from the center "visible" current. In most lightning strikes, you have no idea where the actual strike occurred other than seeing where the damage is. If nothing is burned and charred then you surmise where the current originated by tracing the path of ruined equipment or material.

All EMF is a field of varying density, and this field surrounds all current flow and moves in a circular direction in relation to the current. (right hand rule... for the geeks among us)

EMP is pulse. EMP's relationship to lightning is debatable, but one wouldn't know that from reading sales literature for lighting arresting gear. The effects can be very similar (induced current in electrical circuits), so if one decides to guard against the effects of EMP then who can blame them. But there are more differences than similarities. In the big scheme of things, the primary concern with lightning protection is to eliminate potential voltage between your boat and the surrounding area. In other words, don't be the big Positive in a field of Negative. Bonding and Grounding to make your boat look like the water is the highest priority.

Like everything else, it's all about magnitude. All lightning strikes aren't equal. A weak strike near your boat may not have much affect if your boat isn't at a different electrical potential than the strike point, because there won't be much induced current. A powerful hit anywhere in the area is going to sufficiently change the charge of the strike area enough that you will be at a relative different potential than you were before- and that difference in potential is what then causes current flow. So, in other words- if the strike is sufficiently powerful and/or close, then all bets are off anyway. The best you can do is the best you can do.
I don't follow the logic in disassociating EMP from lightning while discussing induced current. First of all, lightning is a very short-lived event--much shorter than the visual afterimage from the hot plasma (i.e., the visible "bolt"). If you have a direct--albeit partial--discharge through your wiring, there can be evidence of heating. In my direct strike, the #2 ground wire at the bottom of the mast showed deformation of the PVC jacket and lifting of the varnish where the cable contacted the edge of the cabin sole. The current flow was obviously short lived--that is, a current pulse--or I would have had more damage.

We can agree that there are high intensity electrical and magnetic fields associated with a lighting strike and we ought to agree that they are extremely short-lived. Where we may disagree is that a difference in potential can be produced through radiative--not just conductive processes. This would explain how my completed isolated autopilot control head failed after an indirect strike. My theory is that the voltage differential across the circuit board(s) exceeded the breakdown voltage of the semiconductors.

Bottom line: EMP is generally interpreted as short burst of radiated electromagnetic energy. Since my autopilot control head was at least a foot from any wiring, I concluded that it was damaged by EMP. The other electronics were wired in and had scant protection from a high voltage event that would easily overcome a short gap in an open circuit breaker.
 
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