[C320-list] Lightning

[Mike Mellon]

As usual, Allan, an excellent discussion of the issue.  Thank you.

Mike Mellon
LaVida 324 1996

On 12/13/2020 9:34 AM, Irving Grunes wrote:
>    The damage from a lightening stoke comes from the electromagnetic field
> that is generated from the high currents of the strike.
> That is what fries all of the electronics.
> The oven will protect portables and should be used.
> Everything else will be destroyed.
> Irv Grunes
> Formerly 851
>
> On Sun, Dec 13, 2020 at 11:57 AM David Nolte <dcnolte at mac.com> wrote:
>
>> Hi Allan!
>>
>> Thanks for your continuing contributions to the list!
>>
>> Tom - what is your Hull#?
>>
>> David Nolte
>> Beach House
>> #0004
>>
>>> On Dec 13, 2020, at 11:39 AM, Allan Field <allanfield47 at gmail.com>
>> wrote:
>>> Tom - Practical Sailor has several articles on their website that speak
>> to
>>> lightning protection. You would need a login and password to access. But
>>> following is just one article with a recommendation at the end that might
>>> help.
>>>
>>> Allan S. Field
>>> Sea Shadow - C387, #103 (formerly C320, #808)
>>> Columbia, MD
>>>
>>> Most boat owners have only the vaguest idea of what is involved in
>>> protecting their boats from lightning damage. Many believe that their
>> boats
>>> are already protected by the boats grounding system. Most are wrong.
>>>
>>> Just because your boat may be bonded with heavy copper conductors
>>> connecting the masses of metal in the boat doesnt mean that it is
>> protected
>>> against lightning. A bonding system may be a part of a lightning
>> protection
>>> system, but bonding itself offers no protection to the boat unless a
>> good,
>>> direct path to ground is part of the system.
>>>
>>> While neither aluminum nor stainless steel is an outstanding electrical
>>> conductor, the large cross-sectional area of both the mast and the
>> rigging
>>> provide adequate conductivity for lightning protection. The trick,
>> however,
>>> is getting the electricity from the mast and rigging to the water.
>>>
>>> The straighter the path is from conductor (mast and rigging) to ground,
>> the
>>> less likely are potentially dangerous side flashes. Put simply, side
>>> flashes are miniature lightning bolts which leap from the surface of the
>>> conductor to adjacent metal masses due to the difference in electrical
>>> potential between the charged conductor and the near by mass of metal.
>>> Ideally, therefore, the path from the bottom of the mast and rigging to
>>> ground would be absolutely vertical. In practice, this is rarely
>> achieved.
>>> If the boat has an external metal keel, the mast and standing rigging is
>>> frequently grounded to a keelbolt. There are pitfalls to this method.
>>> First, the connection between the bottom of the mast and rigging to the
>>> keelbolt must be highly conductive. ABYC (American Boat and Yacht
>> Council)
>>> standard TE-4 for lightning protection systems require that these
>> secondary
>>> conductors have a conductivity at least equal to that of AWG #6
>>> copper-strand cable. There is no drawback to using an even larger
>> conductor.
>>> Connecting the short conductor to the mast and keelbolt presents some
>>> problems. A crimp eye can be used on the end that is to be attached to
>> the
>>> mast, but you may have to fabricate a larger eye for attachment to the
>>> keelbolt. This can be made from sheet copper. Soldering the connections
>> is
>>> not recommended, since the heat generated in a lightning strike could
>> melt
>>> the solder.
>>>
>>> Then you have to face up to a basic problem. Your mast is aluminum, yet
>>> youre connecting it to ground with a copper cable. Everyone knows that
>>> aluminum and copper are not galvanically compatible, so whats the
>> solution?
>>> While it will not eliminate corrosion, a stainless steel washer placed
>>> between the copper cables end fitting and the aluminum mast will at least
>>> retard it. But this connection is going to require yearly examination to
>>> make sure that a hole isn’t being eaten through the mast. In addition, of
>>> course, the process of corrosion creates wonderful aluminum oxide
>>> byproducts, which have very low conductivity. The aluminum oxide may
>> reduce
>>> conductivity to the point where your theoretical attachment to ground is
>> in
>>> fact non-existent. Once again, disassembling the connection and cleaning
>> it
>>> yearly are essential to maintain conductivity. Constant attention to all
>>> the conductor connections is essential in any grounding system, whether
>> its
>>> for lightning protection or grounding of the electrical system.
>>>
>>> For more information on how to best protect your boat from lightning
>>> strikes, purchase Nigel Calder’s “Boatowner’s Mechanical & Electrical
>> Manual
>>> <
>> https://www.practical-sailor.com/subscribe/main.html?t=Ad1&s=P_Waypoints050813F#books
>>> ”
>>> from *Practical Sailor*.
>>>
>>> On Sun, Dec 13, 2020 at 10:51 AM Tom Grass <tgrass462 at gmail.com> wrote:
>>>
>>>> Wondering about lightning protection on Catalina 320 boats?  I don't
>>>> believe they come grounded (mast to keel) from the factory - wondering
>> what
>>>> the members of this forum have done in an attempt to minimize the
>> impact of
>>>> a possible lightning strike?
>>>>
>>>> Also what is the collective opinion of installing a Forespar Performance
>>>> Products Forespar Lightning Master™ - Static Dissipater
>>>> on your mast?  We're planning on sailing down to the Chesapeake Bay and
>>>> perhaps to the Bahamas in 2021 - just preparing in advance.
>>>>
>>>> Thanks,
>>>>
>>>> Tom and Tracy Grass
>>>> Bucket List
>>>> 2008 Catalina 320 MK II
>>>>
>> David Nolte
>> SuspenderStore
>> 800-393-4508
>>
>>
>>
>>
-- 
Michael Mellon
45 Ortalon Ave
Santa Cruz, CA 95060
mmellon at cruzio.com
831-425-5583 Home