This is a really very good question! I don't
actually know all the answer, but I can offer
a few things closely related.
struck all the time, as do aircraft. Being metal,
folk within are protected (Faraday shield effect)
even if there is damage to the structure.
Lightning protection devices as used on
buildings, connected to a grounding strap have
an array of sharp points, designed to cause
the air to reach corona breakdown point very
quickly when a charged cloud is over. Well before
any strike, the discharge glow starts, and dissipates
the local field by generating ozone and other
gas ions. I think the idea is that if there
is to be a strike, it will hit someone elses
highly charged boat!
I have always wondered
if these sharp points building up a cloud of
ions in the air above actually amounts to a
lightning attraction device, but I am assured
that a sharp point like that immediately and
dramatically reduces the potential of the rest
of the connected bits.
A fat grounding
strap is a safety device designed more to ensure
that a major strike will track a reasonably
safe route over ceramic, brick and other fireproof
surfaces, than to survive the strike itself.
That said, most minor strikes may not do more
than bend it a bit , or melt a few spots.
The actual design of safety strap route,
its location, and what might connect to it where
is not trivial. There are specialist outfits
doing just that.
Protection of the ship
is one thing, protection of any RF kit onboard
is another. GRP vessels are going to be prone
to fire. My guess is that a highest point set
of ioniser spikes connecting to a thick copper
strap, secured over a path of ceramic tiles,
down over the side, might be the main feature.
Choke baluns, or even a few turns coiled
into the coax can provide enough impedance on
the coax outer that a strike transient produces
a voltage pulse enough to break down a intentional
spark gap in purpose-designed connectors on
the antenna side. Thus a strike can be made
to track elsewhere, maybe destroying the upstream
cable in the process, but behind the impedance,
the kit can survive.
Lightning is a great
destroyer of RF kit connected to antennas, but
by using spark gap protectors, chokes, coupled
with overvoltage protection semiconductors at
the kit end, is maybe what is needed.
I do admit that all this is gathered over
time from discussion among working pals. I may
even be misinformed. If there is anyone out
there who *really knows*, able to speak with
authority, and is willing to share some knowledge
for free, please do..