I'm attaching a screenshot ("three-am.png") of my
GPS tracks while anchored. The track begins on the left when we went to
bed (at around low tide). I took the screenshot about 20 minutes after waking up and seeing that the
boat had swung to a new spot. To the right (underneath the "ance" in "Distance") is what looks like the circular
arc of the
boat swinging at its maximum distance from the
anchor. But then we have a new
arc about 10 ft further out (to the right) from the
anchor (under the "H" in "Heading").
I'm wondering: Did the anchor slip (and then recatch) between those two arcs on the right?
My best guess right now is no: It seems more likely that what looks like the arc of a maximally stretched anchor line is actually just the boat drifting a bit inside of the anchor's circle, and/or maybe the
wind picked up little to straighten out the anchor line between the two arcs (although I didn't notice any change to the very light wind). But I'm interested in what others think.
More context:
We have 9 ft tides here and are in about 14 ft of
water at low tide, which was around when the track begins in the left. I took the screenshot at almost high tide. I think we had put out about 140 ft of anchor line (almost all rope). I set the anchor by running the
engine in reverse at medium RPMs for a minute or so. This spot is well known to have great holding.
I wasn't using an "anchor watch" app. It seems like the
alarm would be quite prone to false positives, and I don't want to wake up my spouse unnecessarily. Instead I've been looking at the
GPS track whenever I woke up a little, and sometimes popping my
head out the
hatch to look around. At home I'm a sound sleeper, but on the boat I naturally wake up every hour or two to check on where we are. I think next time I'll add the anchor watch app to my arsenal, but just use a setting that will only wake us up if something's definitely wrong (and/or use vibrate-only, so it's more likely to wake up me and not my spouse).
We didn't actually have any issues. (I'm also attaching a screenshot of our track from the rest of the night. The track going off the
screen is from when we picked up the anchor and left.) But the worry kept me from getting as much sleep as I would have otherwise. This is only my second time sleeping on an anchor on a boat that I'm responsible for, so I'd love to have any opinions/advice that folks can give.