For what it’s worth, when my group went in May 2016 we anchored on the east end of Deadman’s Bay and dragged anchor overnight during some decent wave action and a storm that moved through. The boat had been fine all day, we had been anchored just fine for about 8 hours until we woke up at 2am to realize we were moving. Could’ve been our own fault in location selection, as I know there’s some grassy bottom, but I read our cruising guide later that day and it did mention to use caution when anchoring in that area.
I’m curious to know how deadman’s beach is looking now, that was my favorite stop of my trip! Perfect beach!