No. Ebb the idea is to create a concave shape similar to that of a spoon; this will generate the most resistance. If a blade is filling with a ball of the bottom, it is holding well. If it is letting go of that ball and moving through the seabed, well then it is not holding is it. (In simplistic terms. In fact the "balling" problem has not appeared for the Rocna; even hard clay manages to clear from the blade quite easily. In reality the anchors will bury themselves, but this brings up another issue with testing, as the burial process takes some time. You can't do it when you first set the anchor - it has to have time to work its way down. Therefore the ultimate holding power of most anchors slowly increases from the time it is first set, over perhaps a 12 or 24 hour period, depending on the seabed type).Originally Posted by ebb
But the superior nature of a concave fluke is really beyond debate. Concave is better than flat is better than convex, and this has been proven and demonstrated countless times now. Did you not like Graham Alderwick's comment: "My old 30lb Manson plough, while adequate most of the time, and during settled weather, just would not have cut it under these conditions. They should all be relegated to where they belong – on the farm."
No they will not follow the radius of their curve in the lengthways axis. If they did that we wouldn't get much very good feedback would we. Saying this is like saying a parachutist will rotate vertically around his 'chute as he falls
. The motion the anchor wants to perform is related to the average reaction vector of the blade and the angle of pull as dictated by the rode through the shank. And of course all this is very carefully worked out to be optimum.
The Manson Supreme has no curvature in the lengthways axis because they roll the fluke's two laminated layers rather than fabricating it out of brake pressed sections as we do, and it would be too difficult to get the shape right (curve a piece of card then try to make it spoon shaped, and you'll see what I mean). So this is a result of cheaper construction and nothing to do with core design principals.
You would have to consider other factors also. What about strength of the fluke, strength of the shank (in all different directions), weld/build quality, durability, simplicity and ease of construction (important to the consumer also because a complex design generates quality control issues meaning some units are "lemons"), quality of finish (galvanizing), reliability, fit on bow rollers, value (cost), versatility (different bottom types), I could go on...If I were comparison testing, I would gather ALL anchors (including the Buegel) in a certain sailboat tonnage range and set up a series of real world and straight pull tests. Might even blindfold the testers so that they could fudge numbers for their personal favorites.
If we wanted to do well in your hypothetical "comparison testing" (which is the same as what most magazines continually try to do while never understanding all the factors involved - although not all are as bad as Powerboat Reports / Practical Sailor), we could consider your test set-up and build you the perfect anchor that would win every time. But it would be at the sacrifice of most of the factors listed above.
The Powerboat Reports tests have been mentioned a few times now on this thread. We have a FAQ relating to the results - you can read it here:
www.rocna.com/press/press_0603_ps_faq.pdf
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