[Alberg30] Lightning Protection

[C.B. Currier]

the possibility of or effectivenss of devices to disarm the lightning may b
not effecitve but what about simply channeling the strtike if it does hit
the mast? I understand that keel stepped masts with lead exposed keels are
more effective at channeling that strike. Would it not be at least prudent
to utilize some sort of mast grounding method ?


C.B. Currier
Infinity 57
Daybreak 458



George Dinwiddie said:
>> Bob Chambers said:
>>
>> I completely agree with George, it is difficult if not impossible to
>> really protect the boat.  I do think that installing one of the rods
>> with a brush of wires at the top of the mast is an excellent idea.
>> The theory is that it will 'bleed off the charge around the boat'
>> making it less likely that you will be hit.  I have seen the "St
>> Elmo's Fire" eminating from one of these indicating that they are
>> working.
>
> According to
> http://www.thomson.ece.ufl.edu/lightning/AirTerminals.html#DAS
>
>   Lightning dissipators  The idea that a device might be able to
>   prevent a lightning strike is very appealing to the average
>   sailor.  Devices that attempt to eliminate or reduce the incidence of
>   lightning strikes generally have a bristly appearance caused by
>   multiple conducting points.  Under the influence of an electric field
>   under a thunderstorm, it is undisputed that these multiple points
>   release charge into the air in a similar manner to the
>   phenomenon of St. Elmo's fire.  How effective these charge flows are
>   at eliminating or reducing lightning has been the subject
>   of  investigations by  NASA, FAA, the Departments of Army and
>   Air Force, NFPA, and FDOT.  None of these agencies consequently
>   supported their use.  Scientific papers by scientists in reputable
>   journals have also been negative.  In 1994 Donald Zipse, IEEE
>   Fellow, compared the conventional Franklin air terminal with,
>   amongst other systems,  multipoint discharge systems and concluded
>   "The claims of being able to dissipate any and all lightning
>   strokes have been shown to be untrue."  In a subsequent study
>   that considered only lightning elimination devices employing
>   the point discharge phenomenon, (that is, lightning dissipators)
>   Abdul Mousa, also an IEEE Fellow, documents many instances when
>   lightning struck towers at Kennedy Space Center and Eglin AirForce
>   Base, and one case of a strike to an FAA control tower in Tampa. In
>   his paper Dr. Mousa concludes that "Natural downward lightning
>   flashes cannot be prevented."  His comments on the subject are
>   much more candid in a subsequent posting to the LightningSafety
>   listserve.  His phraseology "natural downward lightning" is
>   carefully chosen, but does cover the case of a sailboat mast.
>
> --
> ----------------------------------------------------------------------
>  George Dinwiddie                             gdinwiddie at alberg30.org
>  The gods do not deduct from man's allotted span those hours spent in
>  sailing.                                    http://www.Alberg30.org/
> ----------------------------------------------------------------------
>
>
> //===============================================================// //
>      Ocean Navigator magazine, for the serious sailor        // //
> http://www.amazon.com/exec/obidos/ASIN/B000066625/alberg30-20 //
> //===============================================================//
> _______________________________________________
> Public-list mailing list -- Public-list at alberg30.org
> http://www.alberg30.org/mailman/listinfo/public-list
> To unsubscribe: email to Public-list-request at alberg30.org
> Include command "unsubscribe <password>" in subject or body.
> Use command "help" for more options.




 //===============================================================//
 //       Ocean Navigator magazine, for the serious sailor        //
 // http://www.amazon.com/exec/obidos/ASIN/B000066625/alberg30-20 //
 //===============================================================//
_______________________________________________
Public-list mailing list -- Public-list at alberg30.org
http://www.alberg30.org/mailman/listinfo/public-list
To unsubscribe: email to Public-list-request at alberg30.org
Include command "unsubscribe <password>" in subject or body.
Use command "help" for more options.

 1026559127.0