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GPS Anchor Alarms
When I bought my sailboat a few years ago, the previous owner left the old Garmin 75 GPS for me. I''ve used it ever since, reluctant to upgrade because of all the waypoints and routes that I''ve loaded in. Maybe next year...
One of the features I turned off and forgot about was the anchor drag alarm. Back when GPS positions were intentionally distorted with "selective availability," turning on your anchor alarm almost guaranteed that you would be awakened in the middle of the night for no good reason.
Now, since SA was turned off by the Clinton administration, anchor alarms work, even with my old, obsolete unit. In my boat, I have a GPS mount at the Nav table, so I can hear the alarm easily from my berth.
If your unit, like mine, requires you to set the alarm distance in decimal fractions of miles, remember that a nautical mile is 6000 feet, .1 nautical miles is 600 feet, and .01 nautical miles is 60 feet.
I like to set the alarm for .02 NM, or 120 feet. That''s usually about how much rode I have out, and it will go off if the boat swings near 90 degrees. I definitely want to get out of bed for any 90-degree swing.