one problem I have never solved, when it bows at night in the Greek island up to 50 kn, we ALWAYS drag..
After 20 knots it always starts to get tricky with anchors. When it's calm I find the weight of the anchor
and chain rode
alone will hold the boat
It sounds like you never really get a good bite on the anchor. During a Thunderstorm I've have 50 knots with a 33ft boat, 33 lbs Bruce, and 120 ft of 10 mm chain in 16 feet of water
hold just fine even after a few circles around the anchor. Here on the Chesapeake the mud is soft enough to penetrate and thick enough to bury quite deep. You almost always have to break out the anchor in the morning with the full force of the boat going forward to do so.
I would think you have more than enough anchor and chain, but are lacking the holding power on the bottom to use them. I suppose it's not easy to always find good holding ground everyplace you go. Some places may have none. I guess you do what you already do and throw everything you have with a rode
in the water
, wait and watch.