rsn48 - maybe something wrong with your
monitor. You are right that the "thumbnail" is blurry, but when I clicked on it, it was as clear as a Bahama anchorage. Their chart would indicate a 50 knot application for your
boat and anchor size. I wouldn't bother to go bigger since you already have, but one size larger is what they recommend for winds greater than 50 knots for your boat. Anchor recommended sizes are all over the place.
Lewmar recommends 44 pounds for a
Delta for your boat. They are an older generation design and have a reputation of dragging far more than the newer design. As posted above, bottom composition is huge in holding. I'd say anchor design, weight and
rode also play big in the equation. I have an 80 pound Ultra, another modern design, with 300 feet of 7/16 inch chain on my
Beneteau Sense 50. It holds so well that in windy
anchorages boats anchor close to us assuming we must be in a wind shadow as the heavy anchor chain generally hangs straight down.