Here’s my thoughts: There is a huge difference in the fluke area for the Rocna sizes. When I first bought a 20 kg (44 lb) Rocna - my first thought after looking at the fluke size was “that seems small”. It did a pretty good job for years though. When I upgraded to the 25 kg (55 lb) Rocna - the difference in fluke size was very noticeable. It’s much larger and made me feel like it would do the job in a wider range of bottoms. In their video, they’re using a 15kg (33lb) - which would be even smaller than the 20kg I had previously.
My take on anchor effectiveness is that it has a ton to do with what kind of bottom you're normally anchoring in. The video shows what seems like sand or very thin mud as the anchor is dragging (which would be hard for any anchor to get a "grip into". (Plus - by their own admission, trying to reset the anchor at 3 knots in the opposite direction is pretty severe. That's how we normally break our anchor out.)
In our PNW area, the relatively dense mud is pretty ideal for the rocna. We do have wind shifts, but not like what they seem to be trying. If I spent my time anchoring in the Bahamas (with it's softer, sandy bottoms), the Rocna might not be as good unless it was larger.
We know the evolution of anchors: Fishermen, and Navy anchors, CQR, then the highly popular Bruce. Now the next generation with large surface area, self righting roll bars or weighted shoes: Rocna, Spade, Vulcan etc. Not to mention the Danforth and Fortress lightweight types.
There appears to be some science - at least experimental science involved in the evolution of anchors. Looks like the guy who invented the Rocna did a lot of work, and his anchor has gotten good reviews. But now there is some concern about the ability of the Rocna, and maybe other spade type anchors to reset after a 180 degree tide or wind reversal.
I find the following articles, and related videos of anchors being set, and reset interesting, and thought provoking.
For the record, I've used a Bruce anchor successfully for 33 years on my C&C 34, and now for a couple of years on my Tartan 3800, but last year I switched to a Vulcan with a weighted shoe, and no roll bar.
Let me know what you think about these write ups and videos. Maybe this is a topic for one of our cruising potlucks...
Anchors they recommend
Rocna reset debate:
Some discussion on the demonstrated test.
My conjecture: Perhaps the scoop anchors all have the characteristic of collecting mud to block the point, or to upset the weighted shoe, changing the ability to set during a reversal.
The video and article of the reset fails:
Corinthian Yacht Club of Seattle7755 Seaview Ave NW Seattle WA 98117(206) 789-1919 (Main line)
(206) 402-6870 (Juniors)
47° 41.14' N 122° 24.22' W