This is a very typical cookie trail of anchoring here in Maine. As you can see the wind started at about 180 degrees from where we were in the screen shot and was at 20-25 knots. It then tapered over night as we moved around 360 degrees. About 4:00 am the wind piped up from the opposite direction of the set and again blew 20+ knots.
We do get 180's very often. Are they as quick or abrupt as they tested them? Usually not and one reason why anchor tests do not always emulate the real world..
Flip flops do & can happen. Flip flops can be caused by the anchor remaining deeply set in the opposite direction. When the wind pipes up enough, in the new direction, the anchor either rotates in the bottom to the new orientation or flips and resets. In order to do this as fast as teh testers did you need an abrupt front to move in. It can happen though is pretty rare. Some anchors do not do well with re-setting or un-set quite easily. The CQR is rather notorious for this.
Years ago we nearly lost our boat on the rocks to what I can only assume was a flip-flop of our Fortress. In the early morning a very strong high pressure front moved in with alarming speed. I was up to take a leak when something did not feel right. Instinctively I dove for the engine switch and got us off the lee with inches to spare. The Fortress had held us for two days in winds gusting to 40 knots from the opposite direction but when finally put to the test, from the opposite direction, was when she popped out never re-set... We moved over 1/8 mile and still the anchor never re-set..
I read the test and was not surprised. All the new gen anchors pretty much re-set quickly. They all got a "Very Good" rating for holding while the old gens only got "good" or poor in the case of the Fisherman style...
The test however was not very realistic and they even admit that. Still the new gens performed quite well. Most times the anchor will rotate slowly as the tide, current or wind change directions. In a few instances you can create a scenario for a flip flop and the new gens have this base covered.
Being that I own all the tested anchors except for the Ultra and Sarca, I still know which anchor I choose. I do my own rather exhaustive and punishing personal testing, which is in slight contrast with the PS tests.
Interestingly enough the two "recommended" anchors are;
1- The most expensive anchor you can buy, the Ultra at $1600.00 for a 35 pound anchor.
2- An anchor not commercially available in the US, the Sarca Excel...
The anchor that took "best choice" is one I actually own two of, the Spade, only I consider them a "second choice".....
I have lots of choices.....