Dunvegan,
As Rich and Tom have said....READ THE PRACTICAL SAILOR ANCHOR REVIEW ARTICLES ... Like Tom, I have a 44lb Spade anchor on my 420... It has been everything that the Practical Sailor articles suggested that it should be....For the past 3 years; from the mud of the northern Ches. Bay to the hard-pan coral bottoms of the Fla. Keys,( and MANY places in-between), it has dragged only once... and that was on the south side of the Sunset Beach, NC Pontoon Bridge. Extreme low tide forced us to wait 2 hrs. before the pontoon bridge could be opened.... Anyway, we anchored in shallow water on the windward side of the channel... Apparently, the anchor couldn't set well in the downward slope of the channel bottom and it slowly dragged (in 20kt winds)... (the other 5 or 6 waiting boats were dragging also). It was the only time in 3 years that the Spade hasn't set, and held securely.Spade anchors are similar to CQR, deltas, etc... but with several important differences. They are a French design; cast in Tunisia.They may be a little more expensive, but a good night's sleep at anchor when the tide shifts and the wind comes up, is worth the price....But, the anchor is only half the solution to secure anchoring. An all chain rode is equally important. If your boat is smaller and you don't want the weight of 200' of chain in the bow, use at least 100', with another 100-150' of nylon rode... And never use less than 5-7:1 scope.