First, my thanks to those of you who responded so promptly. So far it's been constructive. You who added ballast down inside your ballast keel were lucky because the moment arm and, therefore, righting effect, are both greater. My Hunter with a draft of 4.5 feet has a solid, narrow cast iron keel with superficial rust (I sail in fresh water) so the sand bags will go atop it in the bilge. I also appreciate the guy who pointed out to me the added weight of engine mount, tank, etc for the saildrive; it suggests that perhaps 3 sandbags of 60 lbs would not be unreasonable. Next question: will 150-180 lbs of ballast materially slow down the boat? We race in season actively on the Hudson River.