Grounding of boats on the hard???

[Dennis Truett]

I was thinking of running a ground wire from my back stay to a driven ground for lightning protection while the boat is on the hard...
Now... does that make the mast more or less suceptical to lightning?
or should I leave it without, and in that case it is pretty much insulated from ground.

I'm figuring it would be wrong since no one does it. What do ye all say?

As always...Thanks in advance!

Dennis Truett
Summerwind
CD26D

[Ken Coit]

Sounds like a great question for

http://groups.yahoo.com/group/LightningProtection

Some of them are experts.

Ken
CD/36 Parfait
Raleigh, NC

I was thinking of running a ground wire from my back stay to a driven ground for lightning protection while the boat is on the hard...
Now... does that make the mast more or less suceptical to lightning?
or should I leave it without, and in that case it is pretty much insulated from ground.

I'm figuring it would be wrong since no one does it. What do ye all say?

As always...Thanks in advance!

Dennis Truett
Summerwind
CD26D

parfait@nc.rr.com

[Larry DeMers]

Dennis,

I'll leave the conclusion to the experts on Yahoo then..but considering this from an electrical perspective, your boat is on a cradle assumably, so out of contact with ground, therefore electrically neutral and not seen by the stepped leader as it tries to form. I would not want to be the highest object around however, insulated or not. If you are, then your plan of using a driven ground rod connected to the chain plates and rigging is probably a better idea.

A friend of ours (Jerry and Karen on Mystic..owner/editors of Good Old Boat magazine) lost $8K worth of gear this past spring to just this cause. Boat was on the hard, and there was a close lightning strike..they were not even directly struck..and lost everything electronic. I suspect it was the EMP from the strike that took out their gear.
..some of which was not even powered up or plugged in yet..this included their laptop that they used to layout the magazine.

So it does happen..although this is the first one I have heard of in 35 years of sailing and engineering.

Cheers,

Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~Lake Superior~~~

I was thinking of running a ground wire from my back stay to a driven ground for lightning protection while the boat is on the hard...
Now... does that make the mast more or less suceptical to lightning?
or should I leave it without, and in that case it is pretty much insulated from ground.

I'm figuring it would be wrong since no one does it. What do ye all say?

As always...Thanks in advance!

Dennis Truett
Summerwind
CD26D

demers@sgi.com

[John R.]

I was thinking of running a ground wire from my back stay to a driven ground for lightning protection while the boat is on the hard...
Now... does that make the mast more or less suceptical to lightning?
or should I leave it without, and in that case it is pretty much insulated from ground.

I'm figuring it would be wrong since no one does it. What do ye all say?

As always...Thanks in advance!

Dennis Truett
Summerwind
CD26D

Here's a link for you that discusses the propagation of lightning and it's strike potential.

We are in the lightning capital of the U.S. here in Florida. Tampa bay being the worst area. Dissipators and "cones of protection" have both shown results here protecting boats. I've witnessed some cases where both have saved damage to owners vessels over the years. Although I've also seen anchor chains save vessels directing strikes to ground.

If I were you I would use a "cone of protection" method rather than just a single ground lead. A single lead could actually increase your chance of being struck by facilitating a charge to develop at the mast head while a storm passes over head. You want to reduce the potential charge not help it develop. Granted if the boat were struck it would possibly help direct the strike to ground but maybe not. Maybe the strike finds travelling down the mast through the hull a more direct path. With a cone you would have a much greater chance of it dissipating via the ground leads due to the lower resistance of the two leads as opposed to one in addition to their angles.

Though the contrary thought is that by running leads you are creating strike potential because you are facilitating a positive charge to develop at a small poit at the mast head thus creating a possible streamer.

I think you would be best off with a dissipator. Install it and forget it. Having the ions dissipated reduces the likelihood of streamer development in the first place by not allowing a sufficient positive charge to develop.

Consult the archives on this board for references to material discussing these issues in depth.

I tried to make a couple other posts in more detail on this matter for you but they would not post so this one is short and to the point because I'm getting tired of retyping this several times. Good luck.



[img]http://www.cdc.gov/niosh/nasd/images/as048f5.gif[/img]

[john doyle]

I was thinking of running a ground wire from my back stay to a driven ground for lightning protection while the boat is on the hard...
Now... does that make the mast more or less suceptical to lightning?
or should I leave it without, and in that case it is pretty much insulated from ground.

I'm figuring it would be wrong since no one does it. What do ye all say?

As always...Thanks in advance!

Dennis Truett
Summerwind
CD26D

Here's a link for you that discusses the propagation of lightning and it's strike potential.

We are in the lightning capital of the U.S. here in Florida. Tampa bay being the worst area. Dissipators and "cones of protection" have both shown results here protecting boats. I've witnessed some cases where both have saved damage to owners vessels over the years. Although I've also seen anchor chains save vessels directing strikes to ground.

If I were you I would use a "cone of protection" method rather than just a single ground lead. A single lead could actually increase your chance of being struck by facilitating a charge to develop at the mast head while a storm passes over head. You want to reduce the potential charge not help it develop. Granted if the boat were struck it would possibly help direct the strike to ground but maybe not. Maybe the strike finds travelling down the mast through the hull a more direct path. With a cone you would have a much greater chance of it dissipating via the ground leads due to the lower resistance of the two leads as opposed to one in addition to their angles.

Though the contrary thought is that by running leads you are creating strike potential because you are facilitating a positive charge to develop at a small poit at the mast head thus creating a possible streamer.

I think you would be best off with a dissipator. Install it and forget it. Having the ions dissipated reduces the likelihood of streamer development in the first place by not allowing a sufficient positive charge to develop.

Consult the archives on this board for references to material discussing these issues in depth.

I tried to make a couple other posts in more detail on this matter for you but they would not post so this one is short and to the point because I'm getting tired of retyping this several times. Good luck.

--IF-- you are hauling your boat for winter storage, there are probably not too many lightning storms. There are many, many boats hauled out from the Chesapeake, north for the winter & I don't remember any being hit by lightning, but I am only 1 set of ears. I sailed off the coast of W.Palm Beach, Fl. & DO believe in lightning protection. Cape Dorys have all wires lead to a ground plate, which gives you a cone of protection while in the water. If you are not the tallest mast in the close vacinity, why worry any more than normal. What about grounding your through hulls to the supports which are metal & sit on the ground. But maybe that would blow holes in the fiberglass.
John cd31 #18 Bonnie Blue



redzeplin@yahoo.com

[Larry DeMers]

Gotta correct an error in the facts below.. In talking to Karen, editor of Good Old Boats, their lightning strike actually occured while at anchor, not on the hard as I represented to you. They originally thought that they had a near miss, but subsequent repairs and inspection has reveled that they did indeed get a solid direct hit, with extensive damage that continues to be revealed even in the past few weeks.

So it kind of dulls my point that I was trying to make, but the facts be the facts.

Cheers,

Larry DeMers
s/v DeLaMer

Dennis,

I'll leave the conclusion to the experts on Yahoo then..but considering this from an electrical perspective, your boat is on a cradle assumably, so out of contact with ground, therefore electrically neutral and not seen by the stepped leader as it tries to form. I would not want to be the highest object around however, insulated or not. If you are, then your plan of using a driven ground rod connected to the chain plates and rigging is probably a better idea.

A friend of ours (Jerry and Karen on Mystic..owner/editors of Good Old Boat magazine) lost $8K worth of gear this past spring to just this cause. Boat was on the hard, and there was a close lightning strike..they were not even directly struck..and lost everything electronic. I suspect it was the EMP from the strike that took out their gear.
..some of which was not even powered up or plugged in yet..this included their laptop that they used to layout the magazine.

So it does happen..although this is the first one I have heard of in 35 years of sailing and engineering.

Cheers,

Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~Lake Superior~~~

I was thinking of running a ground wire from my back stay to a driven ground for lightning protection while the boat is on the hard...
Now... does that make the mast more or less suceptical to lightning?
or should I leave it without, and in that case it is pretty much insulated from ground.

I'm figuring it would be wrong since no one does it. What do ye all say?

As always...Thanks in advance!

Dennis Truett
Summerwind
CD26D

demers@sgi.com

[Glen]

Dennis:

I had a 27' Erricson sail boat on the hard that was hit by lightning. There were other boats around it. Both sides and behind it. They were fine. I was not the tallest mast. I did not have a ground rod connected to the boat.

I have come to the conclusion that next time I will ground my boat on the hard. I also feel that with lightning, take sound measures to protect your boat (in or out of the water), insure it and just keep telling yourself that "your special, one in a million" to get hit my lightning.

Good luck.



glen@hobbymarine.com

[R James]

Had a friend who lost the interior and all electronics to a ChesBay lightning strike while on the cradles...CaboRico..no other boats affected. Had just been hauled and blocked within the last 3 hours....he's at dinner, hears/sees lightning/thunder storm, cell phone rings w/in 5 minutes....marina says his boat's on fire.
He says he could actually see where the lightning had run round the interior of the boat looking for a way out...finally exited through the starboard aft hull where the jackstand met the hull. Said it blew a fist sized hole in the hull. He'll definitely ground the hull next time he hauls the boat (perhaps by drilling into the hull grounding plate and running a large copper cable to earth). Thunder storms are odd beasts.....you never know where they'll decide to come to ground.



RJcapedory@aol.com