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  #11  
Old 10-23-2013
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Re: Lightning protection- precision 18

It's an 18 ft boat... Drop the mast. Or, better yet put it on the trailer and drop the mast.
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  #12  
Old 10-23-2013
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Re: Lightning protection- precision 18

As stated by others:

a. Take the mast down.
b. Park in the trees.
c. Get next to taller boats.
d. Don't get caught on the water.

Also read this, re. disipators; basically the math doesn't work and it's all statistics.

Sailboat Lightning Protection - Inside Practical Sailor Blog Article

I've installed protection systems that have actually been hit; there is no way they can be fitted to a small boat, the power is simply too great.
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  #13  
Old 10-23-2013
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Re: Lightning protection- precision 18

Quote:
Originally Posted by pdqaltair View Post

I've installed protection systems that have actually been hit; there is no way they can be fitted to a small boat, the power is simply too great.
Part of my job is to repair lightning damaged boats. I get to go aboard lots of them and then work with the insurance adjusters to make sure my customer does not get screwed over.

What I see (generally)

Fuzzy disipators DO NOT prevent strikes - IMHO they are as close to snake oil as we can get today. I have plenty of boats that are hit with them one of them twice.

A shorter mast does not prevent strikes nor seem to limit them - I have plenty of small power and sailboats hit amongst hundreds of considerably taller spars with regularity. Lighting goes where it wants and the height of your mast does not seem to dictate anything.

Bonded well Earthed boats suffer less hull damage - One of the first things I look for is a path to Earth for the lightning. When it is non-existent or the wires too small and corroded there is almost always considerably more hull damage. When the mast to Earth wires are large, clean and well installed I rarely see hull damage.

Carbon Fiber spars are easily destroyed and EXPENSIVE - My friend Kim's boat was hit and the spar damage alone was over 80k. They had a good Earth bond and the hull was fine but the spar was still destroyed and unrepairable.

Bonded boats are hit slightly less - I see less strikes (in my data pool) of well bonded/grounded boats that are hit by lightning than I do of unbonded/ungrounded boats. The unbonded/ungrouded boats tend to get hit more. The spread however is very small and mine is about the same spread Dr. Thompson sees and pretty much inconclusive. The edge however still sides with well bonded boats being struck slightly less.

Frustrating Fact - Even large insurance companies like Boat US DO NOTHING to collect data on strikes to even begin to tell us what may or may not work to minimize damage. They HAVE this capability!!!! I have been pushing Boat US, through Beth Leonard, to come up with a form for the adjusters so that data can be compiled on a larger scale but she's been busy and I have too. Even with that I don't know what she can do to change this situation. My personal strike data seems to line up with Dr. Thompson's but these are still fairly small samples. Insurance companies have access to much more potential data.

You can not prevent a strike - You can however take steps to minimize hull damage by having a well bonded/Earthed boat.

You can not protect electronics - I've seen all kinds of cockemammy schemes drummed up, and the electronics still get fried. Even when not plugged in. A Faraday cage is your only bet but this excludes most installed gear..

Many insurance companies will try to "weasel" their way out -Do yourself a favor and hire a COMPETENT marine electrician who specializes in or is very familiar with lightning strikes. You will pay them to go over your boat ahead of time and to be there to meet with the insurance adjuster. Most of these adjuster/surveyors know squat about electronics, wiring etc.... Defend yourself, be prepared, and it will PAY YOU BACK.

I just had a claim go through on a boat for a customer hit in September. The damage claim was 90% of the "agreed value" of the vessel. Because my report was thorough and completely documented with pictures, replacement models, estimated labor with details, there was nothing denied what so ever.

The adjuster showed up and we went down the estimate list and he just checked stuff off. Done..... Owner had the check two days later. The $300.00 he paid me for my time and report was peanuts compared to what it would have cost him had he gone it alone with the adjuster.

In August I met with an adjuster who was denying the alternator, regulator, Link 2000, tachometer and 3kW inverter charger. The owner had been battling with them for six months. In a three minute meeting with the adjuster/surveyor he had signed off on all of it. Owner sent me a check for $200.00 more than I billed him for as a very nice "thank you".....

It should not have to be this way but today it very much is a fact of life that you need to defend yourself against your own insurer....
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Last edited by Maine Sail; 10-23-2013 at 03:53 PM.
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  #14  
Old 10-23-2013
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Re: Lightning protection- precision 18

Very good info. Maine Sail. It kind of supports the old idea of attaching jumper cables to the shrouds and dangling the other end in the water during a lightning storm. The way I understand the theory is that you want to make the boat "look" the same to lightning as the surrounding sea by equalizing the potential of water and rigging. Having well bonded metal objects like rails and chainplates, attached to a ground plate makes sense. Thanks for posting your experience with this.
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Old 10-23-2013
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Re: Lightning protection- precision 18

Yea, there is no realistic way to protect the boat from being hit by lightning. We were hit 3 years ago.

The best protection for sailors is to have as small a gap as possible between the toerail and the dock. Then do like Brave Sir Robin and run away (preferably inside a building with beer, wine, liquor, and a barstool)
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  #16  
Old 10-23-2013
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Re: Lightning protection- precision 18

Quote:
Originally Posted by smurphny View Post
Very good info. Maine Sail. It kind of supports the old idea of attaching jumper cables to the shrouds and dangling the other end in the water during a lightning storm. The way I understand the theory is that you want to make the boat "look" the same to lightning as the surrounding sea by equalizing the potential of water and rigging. Having well bonded metal objects like rails and chainplates, attached to a ground plate makes sense. Thanks for posting your experience with this.
Not at all. The point of adequate grounding is to attempt to take the brunt of the strike directly to Earth & not allow it to divert off path and go through your hull... With well bonded boats I simply see less of this:



This does not at all mean the strike won't damage your boat, but it can help to minimize hull-sinking damage..There are no absolutes in lightning strikes all we can do is to attempt to minimize damage and the best way I know is to bond your spar/stays to external lead or an external copper lightning grounding system.

When our boat was hit the lightning exited at the dead bottom of the keel and nowhere else. I know some "lightning experts" say this can't happen but it does.... Our hull was 100% perfect but all electronics were toasted.

Our spar is grounded to the longest J bolt in the keel (our keel has the bolts installed at varying depths with the deepest right under the spar. It is bonded with 2/0 wire.

If you have internal ballast then an option like this can be a good choice if you can keep the wire bends minimal.
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  #17  
Old 10-23-2013
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Re: Lightning protection- precision 18

Quote:
Originally Posted by Maine Sail View Post
Not at all. The point of adequate grounding is to attempt to take the brunt of the strike directly to Earth & not allow it to divert off path and go through your hull... With well bonded boats I simply see less of this:

This does not at all mean the strike won't damage your boat, but it can help to minimize hull-sinking damage..There are no absolutes in lightning strikes all we can do is to attempt to minimize damage and the best way I know is to bond your spar/stays to external lead or an external copper lightning grounding system.

When our boat was hit the lightning exited at the dead bottom of the keel and nowhere else. I know some "lightning experts" say this can't happen but it does.... Our hull was 100% perfect but all electronics were toasted.

Our spar is grounded to the longest J bolt in the keel (our keel has the bolts installed at varying depths with the deepest right under the spar. It is bonded with 2/0 wire.

If you have internal ballast then an option like this can be a good choice if you can keep the wire bends minimal.
My ballast, as an example, is completely encapsulated and not grounded to anything. Water from a hole in the hull down at the ballast does not get into the bilge anyway. I have proven this:-) All my metal parts are bonded well with what looks like #6 stranded copper back to a sintered plate by the engine. I think the bonding idea makes a lot of sense (if anything does in this lightning topic) in that if your boat and the surrounding sea all have similar electrical potential, lightning has less reason to be attracted to your mast any more than to the surrounding area as the shortest route to ground. Under those parameters, lightning has almost the same chance of hitting 50' from your boat as it does striking the boat. That is what the grounding system does more than attracting lightning to a safer route through your boat. Lightning is trying to get to GROUND, not the water. If the boat looks like the rest of the water, it has less reason to target the boat. The mast is a better conductor than air so the closer it can be to the potential of the sea, the better. Anyway, although counter intuitive, that's the way I've heard the grounding idea explained. If you have contradictory theories about this, would like to hear them. Once lightning actually makes a direct hit, all bets are off and you're just lucky if it doesn't travel in a direction which burns a big hole in the fg.
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Re: Lightning protection- precision 18

Quote:
Originally Posted by smurphny View Post
My ballast, as an example, is completely encapsulated and not grounded to anything. Water from a hole in the hull down at the ballast does not get into the bilge anyway. I have proven this:-) All my metal parts are bonded well with what looks like #6 stranded copper back to a sintered plate by the engine. I think the bonding idea makes a lot of sense (if anything does in this lightning topic) in that if your boat and the surrounding sea all have similar electrical potential, lightning has less reason to be attracted to your mast any more than to the surrounding area as the shortest route to ground. Under those parameters, lightning has almost the same chance of hitting 50' from your boat as it does striking the boat. That is what the grounding system does more than attracting lightning to a safer route through your boat. Lightning is trying to get to GROUND, not the water. If the boat looks like the rest of the water, it has less reason to target the boat. The mast is a better conductor than air so the closer it can be to the potential of the sea, the better. Anyway, although counter intuitive, that's the way I've heard the grounding idea explained. If you have contradictory theories about this, would like to hear them. Once lightning actually makes a direct hit, all bets are off and you're just lucky if it doesn't travel in a direction which burns a big hole in the fg.
In theory this all sounds well and good but the existing data does not really support it other than for a very small edge to well bonded boats vs. un-bonded.

Beyond that people often lack the electrical common sense to realize that most every spar out there, with a VHF whip, is already at ground potential.

All one has to do is follow the shield of the VHF cable back to the VHF then to the ships ground which is engine/water/Earth. Take an OHM meter and put it on your mast now put it on the engine block or battery neg and you will have continuity. Why? Because the VHF shield is almost always bonded to the mast bracket which is rarely isolated from the spar. Mine is but this is a custom mount I made on my own. Most all masts are already at Earth potential whether bonded with heavy wire or not. Most boat owners simply don't understand their VHF whip is already putting their spar at Earth potential.. The heavy wire does not change the Earth potential beyond the small VHF wire but it can help to take the brunt of the strike to Earth which the small VHF wire does a horrible job at......

Just last week I was just talking with another member here who's boat was hit while on the hard. This makes it fully isolated from the Earth as in no connection at all. The lightning came down the spar into the keel and physically jumped the 12" air gap between his keel and the asphalt.... You don't even need Earth potential to be hit. However if your boats bonding wires are large enough that they can act as a "pass through" then you may just suffer less damage......

The heavy bonding wire is intended to minimize damage not prevent or minimize a strike. This is the area where I do see a large difference in damage results. Well bonded boats with heavy grounds suffer less damage, but they still get hit.
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  #19  
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Re: Lightning protection- precision 18

Quote:
Originally Posted by Maine Sail View Post
In theory this all sounds well and good but the existing data does not really support it other than for a very small edge to well bonded boats vs. un-bonded.

Beyond that people often lack the electrical common sense to realize that most every spar out there, with a VHF whip, is already at ground potential.

All one has to do is follow the shield of the VHF cable back to the VHF then to the ships ground which is engine/water/Earth. Take an OHM meter and put it on your mast now put it on the engine block or battery neg and you will have continuity. Why? Because the VHF shield is almost always bonded to the mast bracket which is rarely isolated from the spar. Mine is but this is a custom mount I made on my own. Most all masts are already at Earth potential whether bonded with heavy wire or not. Most boat owners simply don't understand their VHF whip is already putting their spar at Earth potential.. The heavy wire does not change the Earth potential beyond the small VHF wire but it can help to take the brunt of the strike to Earth which the small VHF wire does a horrible job at......

Just last week I was just talking with another member here who's boat was hit while on the hard. This makes it fully isolated from the Earth as in no connection at all. The lightning came down the spar into the keel and physically jumped the 12" air gap between his keel and the asphalt.... You don't even need Earth potential to be hit. However if your boats bonding wires are large enough that they can act as a "pass through" then you may just suffer less damage......

The heavy bonding wire is intended to minimize damage not prevent or minimize a strike. This is the area where I do see a large difference in damage results. Well bonded boats with heavy grounds suffer less damage, but they still get hit.
I think it's right that there is not much difference at all. Lightning is such a dangerous unknown and acts in such unpredictable and uncontrollable ways that it presents a real problem for anyone thinking they can find any real measure of protection. One thing for sure is that electronics get fried when it even comes close. Makes the idea of sailing without paper charts, as in "NOAA stops printing paper charts" seem pretty lame.
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Re: Lightning protection- precision 18

Maine- Have a 46' boat with 63'airdraft. Fully bonded as per ABYC but has encapsulated keel and no ground plate as of yet. ? Should I install the square plate offered by Ward's Electronics or the strips offered by Dr. Thompson or nothing further? ? if ground plates are installed where should they be installed? Should they be at the heeled waterline as it appears plates near the water surface are more effective then those deeper down? Mast is keel stepped and it very difficult to avoid sharp radius. Is connection between shroud plates and ground sufficient? Dr. Thompson is in Florida is there a good local resource in R.I. area? Are you interested in providing services or referrals for New England sailors?
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