Mantus: Why are your recommended anchor sizes so much larger than Ronca or Manson?
I have a 7000lb empty, so probably 9-10000lb full 28' boat (Pearson 28-2). The conservative recommendation from Ronca is a Ronca 10 (10kg/22lbs) (good to 11,000lb boat). From Manson it is the similar weight Manson Supreme 25 (11.2kg/25lbs).
However the Mantus website recommends a much larger 16kg/35lbs because the 11kg/25lb model is only recommended for boats up to 5000lbs (an odd recommendation since few 30' cruisers are that light).
This immediately turned me off of your product even though some other aspects (the disassembly for instance) were nice.
Mantus' truck test wherein he uses a tree/arm to test the anchors, the Mantus was the smaller than either the Manson or Rocna, but the test was pretty convincing in that ground/~9 lb. anchor range. Mantus vs. Manson, then Mantus vs. Rocna, showed the Mantus holding longer than the others. This was just for small anchors, of course. Maybe Mantus should repeat that test with big anchors, but he is going to need a pretty big truck. Look at the test again.
Mantus vs Rocna vs Manson Supreme, Truck with the spreader bar.mp4 - YouTube
Also, I wouldn't make too much of Rocna's website/data/videos/explanations, which are slicker and more refined. Rocna has been around a lot longer and they've had time to refine their presentations. Mantus is currently small and just getting started. In time, his presentations are likely to be refined to be as good as any. I was once told by a vendor that they could do anything, it just takes time, time and money. I suspect the same applies here in comparing the presentations.
My boat weighs 11,700 lbs. empty and is 32 ft. long. When selecting my primary anchor (before the new ones came on the scene), I looked around and the genuine Bruce was recommended. When I went to size it, my boat fell more or less at the break point....either 22 lb. Bruce or 33 lb. Bruce. I went with the larger anchor. Your loaded weight is somewhat in the same range, and Mantus' recommendation is 35 lb. (between 25 lb.and 35 lb. sizes). For your boat at 10,000 lbs., you say that the Rocna 10 recommendation is 22 lbs. for up to 11,000 lbs. Anchoring requirements are not an exact science and you are clearly at the top range of the Rocna 22 lb., so if one were being conservative, you would pick the next size up for Rocna, which would be a Rocna 15 or 33 lb. So it's all pretty much coming to the same weight point. (I did look at the 5,000 lbs. number for Mantus and I think that is probably low for the Mantus 25 lb. Don't be surprised if sometime in the future, Mantus revises that upward a bit.)