Lightening and bonding

I am still looking for references from list members for my bonding writeup. One if the things people talk about bonding for is lightening. I have a wood mast so lightening would have to go down my stanchions. I did a rough calculation. The power that would be dissipated would be 5 billion watts. That would last just long enough to vaporize my rigging with the energy of up to 10% of a stick of dynamite. I am not going to worry about bonding for lightening. I do think I have a handle on the source of bonding confusion. To prevent electrocution you want to make the voltage difference between any two pieces of metal you might touch at the same time zero. One way to insure that this is the case is to bond them all together with a wire. To prevent electrolysis, you want to make sure that current cannot travel between any two pieces of metal. You do this by making the resistance between them high, so you don't want them electrically connected (no bonding). You need to ask yourself if you want to protect your boat or your crew. Perhaps a better question is, is there a way to do both. Allen

On 12/23/2010 12:29 AM, Allen Edwards wrote: > > I am still looking for references from list members for my bonding > writeup. > I've got more at home, but in my collection of boating articles here at work, I've got: --a CG pamphlet; it recommends bonding for lightning protection, to prevent side flashes. --a Practical Sailor article from Dec., 1993 that discusses lightning strikes as RF, not DC, events. It says that side-flashing is caused by various resistances and reactances; what would be OK for DC is not for RF. They say bonding "may" help prevent side flashes. They conclude that "you'll have to keep a watch on electro-chemical corrosion which can sometimes be speeded up by inter-connecting these systems." --a PS follow up in the June 1, 1994 issue. It discusses grounding systems and endorses bonding to perhaps prevent side flashes. They cite a study showing the boats with lightning protection systems had hull damage less commonly than unprotected boats (7% vs 19% in salt water; 40% vs 75% in fresh water). --in April, 2010 a place called Bay Yacht Sales (www.bayacht.com) had posted three articles on lightning protection, one of which cited the PS article on RF behavior. I didn't find 'em online today but you could contact the firm. --at home, I've got some pamphlets from Florida Sea Grant, which did a lot of work on lightning protection for boats. Try their web site. > One if the things people talk about bonding for is lightening. > > I have a wood mast so lightening would have to go down my stanchions. > My other boat has a wood mast. It's also got a bronze sail track, and more importantly, lying directly under that is a thick 1" bronze plate, running top to bottom, that covers two grooves for wiring. I have grounded the shrouds, forestay, and the bronze plate. My theory is that more conductors are better. There is a companionway directly under the deck-stepped mast, so I do have some turns in the conductors but I tried to maximize the radius on each. I also used multiple conductors on the theory that if the lightning disapproved of one, it might like the other. They all run to a keel bolt on an exterior iron ballast keel. Chris Campbell

I put together a page with several references on lightning. I have not read all of these yet but will put them out there for comment. I put the material on my site as so many of the references I found were to dead sites. This way the material will stay around as long as I do (and I don't care after that). http://l-36.com/lightning/lightning.php Allen