NavList:

Lu,

I found this statement of yours thought-provoking and deeply unsettling: 

>>The offshore sailing community is convinced that a high percentage of the 40 or 50 vessels that simply disappear each year may be victims of rundowns by ships on autopilot.<<

It makes me think that if I ever stop chartering, and actually purchase a sailboat, then AIS will be one of the first things I add.

This said, we have had several people on the list suggest that GPS is virtually fail-safe, from a technical point of view.  The only reason to do celestial is for the esthetic satisfaction that comes from it.

It would indeed follow from this that lost vessels MUST sink because of being run down, or themselves running over a floating container that washed off the deck of a passing freighter.

I think this sentiment is 90%+ true, but one can read on various forums about the destructiveness of lightning strikes frying every last microchip on board...even if they are not wired to the boat systems; iPods showing scorch marks on their screens and digital watches going completely dead.  Clearly, there is something going on not just with direct lightning current but with EMP frying all the microchips into which it can induce a current.

Now, it occurred to me that 100% of the accounts I have read so far of catastrophic lightning strikes were of boats tied to a dock someplace.  But if this happened at sea, and all of your navigation was electronic in nature, then if you are 5 days out of Pitcairn Island, and you have only 8 days of water aboard, a lightning strike that resulted in you missing Pitcairn would be only too easy...and would almost inevitably lead to the loss of life.

     Steel vessels don't have the same grounding issues as fiberglass
     sailboats...and the hull may well serve as a Faraday cage for the
     on-board electronics.

I wonder if SOME of those 40 or 50 vessels that disappear every year go missing because of a navigational failure.  They are never around to document that tidbit, and we are left to speculate about commercial shipping running them down.

And even for vessels that are not sunk, there is the embarassment factor that keeps us from hearing about navigational catastrophies.  I mean, who is ever going to write a book entitled "I was aiming for Victoria, Canada, and ended up in San Francisco by mistake.  My wife thinks I'm a dolt, and says she will never sail with me again if she lives to be a hundred"?

Bob