wrote
A recent lightning storm (not an unusual occurance in Texas) knocked out
most all of my Raymarine instruments. ST 7000+ autopilot display (not the
course computer), ST 60 Multi (2), Wind (2), Speed, Depth. What is
strange
(to me at least) is that the Tridata, which is wired directly to the
transducers and is connected by Seatalk to the others, was not affected.
The repair costs are $900. My question is what, if anything, can be done
to
protect this from happening again. The boat WAS NOT struck by lightning.
There were numerous airbursts and other boats were struck directly (none
nearby). Ideas????

Hi, equipment you suspect was not affected, probably was. The latency of
lightning damage may have caused more problems than are presently apparent
from such a nearby strike.

Unplugging your sensitive equipment is the only sure way to protect it from
lightning. Equipment designed to be extremely robust (a high withstand on
the front-end electronics) could possibly benefit from surge suppressors
made for DC systems. Others would likely fail even with expensive surge
suppression, as the clamping voltage level is still high, and barely fast
enough to handle any form of induced lightning energy. The surge suppressors
are made for power line surges, and while they could help, I would suggest
you ask your equipment manufacturers before you apply expensive treatment in
that respect. In the bonding department, you might prevent sharing a charge
between equipments if the units were well bonded to a single point ground.
That's a tough design to include in a yacht, where aesthetics and available
space are always at odds. In that case, refer to the first suggestion ;-)

Best regards,

Jack Painter
Virginia Beach VA