The vessel is a 1952 Feadship, 56' LOA, 13'2" Beam and a draft of 4'6". Steel hull, twin 671 detroits. I just finished installing 16 AGM batteries weighing 100lbs each. They were installed almost exactly in the center of the vessel lengthwise. They are just slightly to port of centerline and are about 20" below waterline. As soon as I installed the bank I noticed that the vessel has become "tippy", as I step onto the side deck from the dock she now noticeably rocks, which she had previously not done. I must say I'm a bit confused as I would think that adding 1600 lbs of weight below waterline would have made her more stable, not less.