With the beam on those ULDB racers around 20 or so feet, having a full tank to windward can provide a lot of torque to keep the boat flat. We hear on the news what happens when they gybe without draining the windward tank... On a MacGregor that''s 6''wide and where you''re not going to empty the leeward and fill the windward tank each time you tack, it''s not very efficient -- its more like sailing around with your bilges full. Though it may be more "stable", it is not fast or efficient. A lifting keel or weighted centerboard would provide better flattening and better performance, generally. If your car can''t pull the weight and you want stability, perhaps a cat or trimaran would be a way to go.