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PostPosted: Sun Jul 29, 2012 2:58 pm 
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Has anyone developed a system for grounding a fiberglass mast? (I know the best protection is to get off of the water.) I need a basic "how to."


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PostPosted: Sun Jul 29, 2012 6:21 pm 
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I would hazard a guess that no matter what you did to ground a carbon fibre AI or TI mast, if you get a direst hit, you would be toast...

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PostPosted: Sun Jul 29, 2012 7:09 pm 
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grounding the is relatively easy, run a heavy gauge wire from above the mast tip to below water level. heavy gauge = 0 or 00 or thicker copper wire. the boat will still be destroyed by the strike and everyone aboard will still get hit from secondaries.

you would need to build a Faraday cage around the passengers to protect them from the strike. With the amount of exposure on an Island, passengers will surely get zapped even if it's just water conducted.

j

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PostPosted: Sun Jul 29, 2012 8:24 pm 
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You want butter with that? LOL

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PostPosted: Mon Jul 30, 2012 1:18 am 
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I have been sleeping on the TI as thunderstorms passed above (well I sure waked up). Not extremely safe, but taking down the mast, laying down and being a fairly short distance from the shore and its trees should lower the risk quite much. Quite scary anyway.


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PostPosted: Mon Jul 30, 2012 7:18 pm 
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Location: Keyport, WA, USA
Since it is not a conductor, it would not be a target. Metal masts definitely, but these should not need grounding. No, don't go out and do a Ben Franklin with it, but I would not panic. If you do manage to get caught on the water, head to shore immediately. Your body, unfortunately, is a better conductor than the mast on an Islander. The lightning won't be coming after your mast, it's going to come after YOU.


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PostPosted: Mon Jul 30, 2012 7:21 pm 
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Steve0 wrote:
Since it is not a conductor...
???

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PostPosted: Mon Jul 30, 2012 8:45 pm 
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Location: Cape Coral, FL
just a couple of facts...

the mast is carbon fiber not fiberglass so it is very conductive
everything will likely be wet from rain which is very conductive
at a peak strike strength of 6 billion volts, things that aren't normally conductive become so
lighting is most likely to strike the tallest object not necessarily the best conductor
when lightning strikes, a broad area is a is affected

the following is stolen from: http://www.ehow.com/about_6525062_effec ... -rods.html

How Lightning Rods Work:
Lightning travels from clouds to the earth and then back to the clouds. Although lightning is nothing more than a buildup of static electricity within clouds, between clouds, or between the earth and one or more clouds, that buildup can be dangerous when it discharges. A positive charge seems to develop more at the tops of the clouds while the negative charge races toward the earth, ionizing part of the air around it as it travels. As a rule, that negative charge will hit a tall, exposed object on earth since that object shortens its path to the ground. The charge will then return to the clouds because it is attracted to the positive charge there. A lightning rod works by allowing that negative charge to enter or leave the earth without damage to non-conducting materials.
A Final Word:
While lightning rods have proved effective in directing lightning away from buildings and other structures, it will not keep lightning from striking. In addition, a direct hit to a building or to a nearby power line that results in a power surge can still cause much damage.


best solution is to get to shore, unstep the mast, and take shelter

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PostPosted: Tue Jul 31, 2012 12:01 pm 
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I did quite a bit of reading about lightning strikes while sailing monohulls. One item repeatedly came up...don't count on your protection design to work as you planned. Some people connect a chain to the mast to conduct the charge into the water, however, the surface area of the 'grounding plate' is very important. Chains don't have much surface area. Many bottom grounding plates are quite large in area. One boat I owned had a large gauge cable bolted from the mast to the lead keel. The boat got hit by a bolt...it vaporized the VHF mast antenna, ran down to the keel, but also jumped to the interior wiring. It melted almost all of the wiring, blowing out all of the connected electronics. In addition, it jumped from the interior wiring through the fiberglass sides of the boat into the water, blasting multiple craters in the gelcoat.
The interior wiring did act as a 'Faraday cage' protecting everyone in the cabin from the strike. Luckily no was touching any metal in the boat when it was struck.
I wouldn't waste the time and effort to construct a 'conductor' from the mast to the water. The mast base is metal and attached to the bottom of the Island. Any bolt would simply blast its way through the bottom.


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PostPosted: Tue Jul 31, 2012 2:51 pm 
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Another idea is to take a bath as the thunderstorm passes. Being connected to the Hobie Island with a rope would probably not be dangerous if the rope is under water. The lightning will still destroy the Island, but that is less of a problem. Unless you and the remains of the boat is drifting out in the sea. Better have a floating device and a waterproof handheld VHF and/or cell phone. Hopefully there are no sharks in your area.


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PostPosted: Tue Jul 31, 2012 4:34 pm 
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Here's my story of lightning and a TI.

My friend and I sailed north from Tampa for several hours on a hot August day. We saw a storm ahead of us but it was far away and heading on shore so we didn't worry. I watched the band of sunlight along the shore get wider and wider as the storm moved inland. Then I watched it get narrower and narrower as the storm turned around. We were 2 miles from the nearest very small island. The next 45 minutes was a very stressful race. There was so much lightning coming from that storm and the island could not get closer fast enough.
It soon became apparent that we would not reach land before the storm reached us. We discussed our options at length. Ultimately we decided to drop anchor, and move down the anchor line to be as far away from the TI as possible. The thought was that if we kept low in the water if lightning hit it would strike the boat and not us. Being 50' from a hit sounded a lot better than taking one directly.
What followed was the most intense hour of my life. We clung to the anchor line. Repeatedly we discussed the concept that we should stay close together "you go we go." It sounds corny now but it was comfort then. We stayed in the water listening to the innumerable bursts of thunder wondering if we were going to get hit. It was absolutely terrifying. I seriously can't come up with effective words to describe it. Bobbing in the water waiting to be struck by lightning was the most helpless feeling.
The storm passed as quickly as it came. We did not get hit but I will never forget that day.
I learned my lesson. If there is a possibility of lightning I stay on the shore. I cannot recommend strongly enough that you stay as far away from lightning storms as possible
Please.


Last edited by SeeSharkGoFaster on Tue Jul 31, 2012 5:33 pm, edited 1 time in total.

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PostPosted: Tue Jul 31, 2012 5:31 pm 
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Location: Calga NSW, Australia
Would a boat with the mast dropped be much more likely to be hit by lightning than a person in the water?

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PostPosted: Tue Jul 31, 2012 5:40 pm 
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Cool story.

Jumping overboard in a squall - now that's a calculated risk!

Lightning will spread for some distance, on and in the water surrounding a strike. It's hard to know what a safe perimeter or depth would be. If the wet rope was above water, you're in trouble holding it,.. those thick rubber fishing gloves would be nice to have though. At least for the placebo effect.

It would be interesting to see the results of anchor lines/chains on vessels hit by lighting. Do they act like a grounding rod, carrying the charge down to the bottom? (And if you're shallow enough to anchor a TI with 200' of line, you're probably close enough to swim safely to shore).

Hobie Crafte, your energized VHF radio and cell phone will make you a MUCH better target for a strike. Oddly enough, you should turn those OFF when you feel most in danger. (Another sad calculation).

If you're not smart or lucky enough to avoid being on the water in an electrical storm, look on the bright side. Your swamped, melted, breached hull will still float and provide a bright yellow marker for the search planes or boats who later come to retrieve your corpse, which hopefully is still tethered to the Hobie.

Cheers! :wink:


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PostPosted: Wed Aug 01, 2012 1:51 am 
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Location: Sweden
I wouldn´t want to hold the anchor line if the anchor is at the bottom. Sounds dangerous to me. A separate line is a better idea.

You can have the VHF and/or cell phone shut down as the thunderstorm passes, but I dont think they will attract the lightning.

A Hobie Island is a bigger and higher target for the lightning than a human head in the water, even without the mast.

An intensive lightning while you´re out on the sea sure can wake up the monkey inside. You will feel like a scared animal for a while, even if you have taken down the mast and is lying down or diving into the water.

"look on the bright side. Your swamped, melted, breached hull will still float and provide a bright yellow marker for the search planes or boats who later come to retrieve your corpse, which hopefully is still tethered to the Hobie."

Most reassuring, isnt it?


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PostPosted: Wed Aug 01, 2012 8:13 am 
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Location: CLEARWATER, MN
When the lightning hit my monohull, it blasted the interior wiring and some of the water line gelcoat. Multiple small holes burned right through the fiberglass hull at the water line (about $5,000 damage just to the hull)
We were anchored in a sheltered cove at the time, surrounded by half a dozen other sailboats. When the bolt hit we quickly checked for damage. The nearest crew called over to us to see if anyone had been hurt...nope.
They said they saw the bolt hit the mast...they were astonished that they saw ten foot leaders jumping out from the water line into the water.

I was told to get out of the water, especially salt water, if there are lightning strikes. The charge can travel quite a ways around the strike. You may be hit on the boat or in the water. But in the water, if you are unconscious you have a better chance on drowning.


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