200 lbs also
I agree with all previous replies. I will also add that length of chain and mooring line is equally important. A heavier mushroom won't help if the boat is lifting it off the bottom. A 1 to 3 (rise to run) maximum slope is recommended for high tide I believe. Don't skimp on the heavy bottom chain, as that is what forces the mushroom do its job correctly (i.e. on its side)