A GPS failure? Do you remember the sextant?
The first question to ask is what do you mean by a GPS failure. If we are talking about a malfunction in the main GPS charter/plotter this is where redundancy comes in. We carry two backup portable GPS units on the sailboat with extra spare batteries. Therefore, the odds of everything malfunctioning are next to nil. That is of course provided the signals from the GPS satellite system are all functioning. Yup, it is actually possible (thankfully not too probable at this time) for the US Global Positioning System to stop working as hypothesized in Wired’s Oh, Nooo! What If GPS Fails?
Not so much because we are paranoid of such massive GPS failure, but because this is totally retro-cool: we are taking a sextant onboard O’Comillas along with a 2003 Almanac and Norie’s Nautical Tables and paper charts. Odds are, we won’t “need” any of this, but Dad and I felt it would be really cool to trace our voyage on paper charts using a sextant. The sextant we chose was a Mark 25 Sextant which instead of a split mirror (the kind I’ve seen before) it uses beam converger or full horizon mirror. Of course, until we get completely confident with the entire sextant process we will be double-checking our answers with, you guessed it, one of the GPSs onboard.