Lightening Attraction

[happyholliday]

Has anyone seen any information or articles about the increased possibility of lightening strike by installing a five foot radio antennae connected to the aluminum body of the pontoon boat?
Happy

 

[mike64]

Re: Lightening Attraction

This article might help. It specifically addresses the scenario of lightning hitting a boat antenna (and how to protect against it) about halfway down the page:

http://www.cdc.gov/nasd/docs/d000001-d000100/d000007/d000007.html

 

[happyholliday]

Re: Lightening Attraction

Thanks Mike64,
That is an excellent article. The information is primarily focused towards larger cruiser boats.

From the article, I can deduct that I if I put my antennae on my top or highest canopy truss and properly ground it with a 1' square ground plate in the water via 8AWG, that if lightening strikes I may be in a safety cone of sorts. I can also fabricate, a separate lightening rod system to better protect the boat.

But what I was curiious about, is does the placement of the antennae (let's say on the command console) increase the likelyhood of a strike even though I have the aluminum canopy trusses going over head?

I have learned that on a foggy day on an inland lake or waterway the diameter of conductivity significantly increases around high voltage wires that cross above the water. So you need to stay very clear of thse wires in the fog or light rain.

One has to wonder that if in heading to shore - trying to get out of the rain and you have an antennae up - are you dragging or creating a wave of charged particles behind your boat that could better attract the strike.
Not that I want to ride int eh rain, but more I respect the nature of lighteing and want to weigh the value of better recreational reception to increasing my likelyhood of a strike.

Thanks again the great article.
Happy

 

[Arabian180]

Re: Lightening Attraction

One thing is for certain. Lightning has never read any books. It's going to do whatever it wants to do.
With that said,
In most instances it will seek the shortest path to ground with the least resistance. The key here is to give a strike somewhere to go besides through you or the equipment. Then again a direct hit will probably kill the radio.

Being you're install is on a pontoon you definitely want to ground the antenna to the pontoon frame using an adequate size wire. I use braided tinned copper strapping on all of my radio equipment. Also bond everything together with braided strap, pontoon to pontoon, pontoon to frame ect. Anything metal should be bonded together in as many locations as possible. More straps = less resistance it also gives the radio more ground plane to work off of. ++. Not that you'll need it at VHF freq. but every little bit helps.

I don't think the metal plate you spoke of is necessary seeing you have two huge metal tubes in the water. (3 if it's a tritoon)

A collapsible antenna mount would be a good idea too for obvious reasons.

There is no substitute for use of common sense. If you hear /see it coming get off the water.

Good luck Sparky !

 

[David Greer]

Re: Lightening Attraction

Here's a follow-up question, b/c I don't know: If you are in the middle of a body of water in a big old honkin mass of aluminum and stainless steel, isn't the lightning going to hit you regardless of an extra 5' of height? IOW a bolt coming from 2000 feet would read your 10' superstructure as well as 10' + 5', right?
Now I can see grounding for reasons in any circumstance, but the specific question concerned the added antenna.
ALso, on a fiberglass boat, should you run a braided ground back to the motor? Off the transom on a dedicated ground?
thanks

 

[bowman316]

Re: Lightening Attraction

The lighting is going to hit the first thing that it can, and Puttling a lightening rod on your roof is a very good idea. Just run a heavy guage wire to the water. Now Idk if you want to ground that wire to the pontoon, or just the the water, and not touch it to the toon. Cuz running electricity thru the toon might get you too.

The steel, being the highest point on the whole body of water, will attract any lightenling close. Being out on the water in a storm, you are almost guaranteed to get struck, like a cowboy being out on the prarie.

 

[Arabian180]

Re: Lightening Attraction

Here's a follow-up question, b/c I don't know: If you are in the middle of a body of water in a big old honkin mass of aluminum and stainless steel, isn't the lightning going to hit you regardless of an extra 5' of height? IOW a bolt coming from 2000 feet would read your 10' superstructure as well as 10' + 5', right?

Yes it is going to see you as the shortest path reg of the extra 5~8' antenna but minimizing height would seem to me a good idea. Not to mention the collapsible mount will keep you from whacking low limbs and overpasses on your way to and from.

Now I can see grounding for reasons in any circumstance, but the specific question concerned the added antenna.
ALso, on a fiberglass boat, should you run a braided ground back to the motor? Off the transom on a dedicated ground?
thanks

For current supply and safety reasons, radio power wires both positive and negative should be run directly to the power source and fused close to the battery.

Braided is not required but my preferred for the antenna ground It provides a DC ground as well as a good RF ground. It should be attached to as much metal as possible. The engine is a good choice on a FG boat. If it has any chances of diverting a strike hopefully it will go through the out drive, prop shaft, ect..
I'm not sure about putting grounding plates on the hull? Talk about throwing a monkey wrench into hydrodynamics. I guess it would be Ok on a displacement hull where planing and friction weren't a major concern.
I don't see a FG boat as being seen by lightning as having alot of "Ground Potential". So actually I think a FG hull would be less likely to attract thus safer. But like I posted before. Lightning hasn't read any books and will do whatever it wants.

I've been an Amateur Radio Operator for 30+ years
These are just my opinions and methods. I am sure there are others out there that work as well or better.
I'm of the opinion that nothing is 100% when discussing lightning and the protection from. If it hits you and you and your stuff survives you got lucky. Next time it may cook your noodle.

Be Careful & Happy Boating.

 

[bowman316]

Re: Lightening Attraction

I would suspect that having a fiberglass boat (which does not conduct electricity) will help you in a storm. You will still need a lightening rod, but the fiberglass will ensure the lightening goes thru the rod, and never touches you.

Imagine that electricity flows like water. And the fiberglass is like a hill, and the conductors are at the bottom of the hill. The electricity is not going to flow up hill, thru the glass, It will go down hill, all the way to the water, when it dissapates. The path of least resistance.