AIS and Knot Meter Requirement

[sleddog]

Hi Philippe - an indirect (or direct) lightning strike to the boat is a more likely issue than the GPS constellation failing. A strike will take out the boat's on-board equipment containing integrated-circuits (IC) chips, at which point you're toast. I do carry a sextant, printed nautical almanac, HO 229, and believe it or not an analog/mechanical wrist watch - no battery inside the watch. I even know how to use it! Add some plotting paper and large scale paper charts, a pencil, straight edge, protractor - and you're good to go.

Perhaps super-old fashioned, but that stuff does help me find out where I am when all the fancy stuff is toast. And I have a Monitor windvane - not that you'd want one of those bolted to the transom of your Class 40! Lightning squalls are no fun, lightning bolts to the water are even worse.

Thanks to Beetle for this reminder why Dead Reckoning skills and basic equipment are not things of the past. My experience has been lightning strikes do not discriminate, and grounding techniques are wishful thinking after seeing lightning strikes in proximate waters travel into the yacht and up the mast.

If you doubt this, consult Synthia who helped refloat Commodore Tompkin's Wylie-39 that was sunk by a lightning strike while anchored in close proximity to the Kaneohe YC July 24th, 2016. Though the mast was grounded with heavy 3/8" cables to a ground plate centered under the butt of the mast, the engine alternator had its lug vaporized, the charge went through the Alpha and NKE autopilots, a Kauri scarf joint in the interior joinery of the hull was split, and, most amazing, 3 diesel injectors were loosened. Ironically, the boat filled due to the violence of the strike causing hull distortion that fractured a PVC sink drain pipe affixed to an open through-hull fitting aboard the unattended FLASHGIRL.