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post #8 of Old 07-26-2015
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Re: Does anyone really know what time it is?

My Raytheon C90W had a brain freeze a few years back. It was only a few years old. The result was loss of electronic charting, including the feed to my autopilot. So it was back to the handheld GPS chartplotter and hand steering for the next 35 miles.

When I contacted Raytheon via phone, they suggested a "factory reset", which is easy enough if you had the instructions. That worked, but I didn't read "the fine print" and didn't realize that the time defaulted to Greenwich Mean Time--a 5 hour difference from our area. As a result, my tide and current data were significantly off. My wife knew better: she had checked the printed tide chart and told me my impression of the tide was way off!

There were 2 lessons learned from that Raytheon brain freeze. (1) You need to maintain and crosscheck paper data with your electronic data when in doubt. (2) You need to consider failure modes when you network your electronics.

Regarding point #2, my primary chartplotter (the one that froze) was the pass through for my GPS data (which comes from a "mushroom" unit via the autopilot computer.) When it froze, I lost position and instrument data to my secondary chartplotter, so it was generally useless until the master unit was reset.

Having learned my lesson, when I changed my VHF, I opted for a unit that had a built-in GPS antenna. My intention was to always have a GPS input for the DSC function, but I also have lat/lon displayed, even on the RAM unit in the cockpit. The only downside is that the VHF base unit down below can take 5 minutes or more to get a fix.
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