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ASK THE EXPERTS
SOLUTIONS FROM THE BoatU.S. TECH TEAM
I read your article on lightning in the June eNews. I put my radios and backup
GPS in our sailboat oven during electrical storms while cruising, thinking that
the oven is similar to a Faraday cage with only a small glass window. Is there any
evidence to support using the onboard oven to protect electronics? We have
a ketch rig with antennas on both masts, monitor the lower mast radio during
storms, and disconnect the main mast antenna. I also rig a chain from baby
shrouds into saltwater from the mast during lightning storms, even though the
main mast is grounded.
Ft. Walton Beach, FL
DON CASEY: There’s ample evidence that an enclosing metal cage or box provides good
protection from the electrical field that accompanies a lightning strike. Thus putting your
electronics in the oven should protect them from nearby strikes and possibly even from a
direct hit. Sailors have taken this precaution for decades and all reports I’ve seen suggest a
good outcome. A glass front should be closed with a cookie sheet or similar metal shield to
perfect the enclosure.
Grounding masts, disconnecting cables, and putting electronics in the oven pretty much
exhaust your opportunities to mitigate the
consequences of a strike. I’ve seen scant evi-
dence that dissipaters and other such devices
have any effect. Giving lightning a good
path to ground offers the best protection for
people aboard. Chain can work, but because
aluminum is a much better conductor than
stainless steel, the bulk of a lightning strike is
likely to travel down (or maybe up) the mast.
That makes grounding the base of the mast
with as direct a conductor as possible far
superior to chain clipped to a shroud.