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· Learning the HARD way...
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Some say bond all through hulls to help mitigate the impact of a lightning strike. Others say not to tie the through hulls to the bonding circuit, because it can lead to galvanic corrosion of the through hull by completing a circuit between all the metals on your vessel (and those vessels in the marina with you) through the bonding wire. I am in the latter camp, although my mast and rigging are tied to a bonding wire that runs to a keel bolt.

I do not believe that either case has been definitively made.
 

· Learning the HARD way...
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Through-hulls should be electrically connected to the 'bonding' system ....

Here's the latest thoughts on lightning protection from the 'guru' of boat lightning research (formerly from Florida State Univ - 'that' guru). Notice that this expert's opinion leans more towards dissipation of lightning from a boat AT the waterline (where most through hulls are located).... which is much different than 'the old standard recommendations' Marine Lightning Protection Inc.
Good stuff there!
However, a single ground plate is inadequate to prevent sideflashes, necessitating multiple interconnected conductors. These cause a whole new set of problems:
  • accelerated galvanic corrosion or loss of sacrificial zinc's;
  • electrolytic erosion in marinas with ground currents leakage;
  • many mounting bolts and hull penetrations, each one raising the risk of water seepage;
  • additional drag since plates should have exposed edges.
Through-hull transducers, fittings, and all immersed metal, including outboard drives, also inadvertently act as lightning grounds. A typical scenario for an ungrounded smaller powerboat, such as a 20' fisherman, is for lightning to attach to the VHF antenna (vaporizing it), spark through the electronics panel (destroying all electronics), travel into the battery ground or control cables into the outboard solid state ignition (rendering it inoperable), and then spark into the water through the drive unit. Any transducer such as a knotmeter is also likely to be blown out, possibly leaving a hole where it was mounted. This scenario assumes that no crew member is unlucky enough to be bridging a gap along the way.
...

In summary, the major problem with charge dissipation into the water is how to provide the appropriate number and distribution of grounding conductors, to eliminate sideflashes, while minimizing the corrosive effects of multiple immersed conductors that are bonded together.
Reading on, it appears that the website proposes the installation of dedicated lightning dissipation electrodes;



Here is their "suitable design for [the installation of these on] a sailboat"


I don't have these, and I doubt that anyone here has them on their boat either.

As I said, I don't believe that there is a definitive, and let me add practical, answer...
 
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