Hi Don, Jees Don, first you blast my short snubber plan with the huge surge displacements caused by waves and now you are attacking the very foundation of my wind force calculations and all that ensues. Is there no solid foundation to anchor theory? >I got those numbers based on actual tests run independently by Robert Smith >and myself. Is this the Bob Smith who is a boat designer in the Bay Area? >On the other hand, if you take dynamic loads into account, the ABYC tables look >progressively better until you face extreme dynamic conditions then my >calculations show the ABYC tables under estimate the load by a factor of 2 or >so., especially with all chain rode. By extreme conditions do you mean breakers? >>The boat, a Krogen 39, has about 160 sq. ft of frontal area. So >>starting with F = 0.004 AV^2 the anchor force due to 42 kn. winds, no gusts, >>no breakers, no waves, no safety factor, is 1129 pounds. << >The calculations you did above are based on the classic drag equation which is >the same equation used by Robert Org and also has considerable safety factor >built in. OK, then what is the "correct" equation? >In your case, It is just hidden in the drag coefficient (.004) and >the over estimation of the exposed area. I do not know how closely you >calculated the exact exposed area, but if you used some sort of rectangle >(heightXwidth) it is probably quite a bit over the actual true wind area. I did it reasonably close - I used used 8 rectangles and omited the shrouds and life lines. I got 158.75 sq ft which I rounded off to 160 sq ft. >Nick you have to expect that these two numbers would agree they are based on >the same equation. The difference is that ABYC doubles their number to >account for Dynamic loads. If you did the same, your numbers would only be >off of the ABYC number by 6%. Peanuts in the anchoring world. >You see what I am saying here Nick is that you can not use the drag equation >to check the accuracy of the drag equation. Heck why not, I am pretty good at that sort of thing. >Ok, so if this idea is right, why do anchors fail? Because anchor load is >only 1/3 of the question. The other variables are poor anchoring techniques >and bottom strength. But don't let me get to far ahead. If you have other >questions, keep the cards and letters coming. OK Don, i'll bite, What are poor anchoring techniques and what problems do they cause?, and What about bottom strength? This last one sounds like a Captn Wil bell ringer. >Don Dodds >North Pacific Research So, Don, what do you research in the North Pacific? Via con Dios, Nick