New Antenna - Lightning Protection?

[Stephen Crampton]

I am thinking about installing an antenna at my masthead. If I do so, do I need to also install a lightning rod, or does the aluminum mast itself provide enough grounding protection (the chainplates are bonded to a ground plate in the keel of my CD 22D)?

Also, would anyone recommend one of the "bottle brush" lightning dissipators?

Thanks in advance for your suggestions,
Stephen



[img]http://www.star.net/People/~sailing/boat1.jpg[/img]
sailing@star.net

[Bill]

Somewhere I remeber reading that the manufacturer of the "bottle brush" lightning protection system (which had something like a $1000 insurance guarantee (sp)) was unable to meet the demand of owners(who wanted their $1000) whose boats had been struck!! I dont know, I may just be day dreaming, but once I read something, I normally remember at least the gross details!

Not positive though.

Bill

I am thinking about installing an antenna at my masthead. If I do so, do I need to also install a lightning rod, or does the aluminum mast itself provide enough grounding protection (the chainplates are bonded to a ground plate in the keel of my CD 22D)?

Also, would anyone recommend one of the "bottle brush" lightning dissipators?

Thanks in advance for your suggestions,
Stephen

cd25d@clnk.com

[D. Stump, Hanalei]

Stephen,
Understand that any lightning protection reduces the height of the mast to that of sea level. It doesn't dissapate a "charge" or anything like that. It simply makes the mast look like it has no height(technically, the potential of the mast is the same as the surrounding structures). Adding an antenna to the mast head will not increase the chance that you will be hit. If you are ever hit, the charge should travel through the shortest path to ground and will in most likelyhood blow the ground plate right off of the boat. A lightning hit has a tremendous amount of current! If I were you, I wouldn't worry about it, if your shrouds are already grounded, it is unlikely that you will ever be hit(I think you run a greater risk of being snake bit!) A squall at sea at night is something to behold! Batten down the hatches and enjoy the light show!!!

Dave Stump
Captain Commanding
s/v Hanalei CD-30

P.S. I did sail with a skipper once that would hook a battery jumper cable to to his after stay if lightning were around and drag the end in the water, he felt it was extra insurance, don't know if it helped, but he was never hit!

[John]

I am thinking about installing an antenna at my masthead. If I do so, do I need to also install a lightning rod, or does the aluminum mast itself provide enough grounding protection (the chainplates are bonded to a ground plate in the keel of my CD 22D)?

Also, would anyone recommend one of the "bottle brush" lightning dissipators?

Thanks in advance for your suggestions,
Stephen

Run a search under "lightning". Several months ago a few of us had some intersting discussion on this very topic. I know the dissipators have a strong following these days from my continued information gathering on this topic. Many land based antenna systems use them with great success. Power plants and other vulnerable infrastructure have excellent results from their use. They are in demand here in Florida, the lightning capital in the states! Many boats get struck down here, its a serious topic. Make sure your bonding wires have no tight turns in them and all connections are clean and tight. You should have nothing smaller than 6 AWG wire used on the bonding. Your dynaplate is not going to blow off, it is possible but not likely, if there is great resistance then the likelyhood rises. Thus the good connections and wide radiused turns in your bonding wires.