The water ballasted design was four times more stable at 10 degrees of heel, three times more stable at 30 degrees , and twice as stable at 50 degrees . The two boats had equal stability at around 80 degrees, and the twin keel capsized at 115 degrees. The single keel held out until 130 degrees. The twin keel design has a solid stability advantage under 80 degrees of heel, and in the event of a capsize, the water ballasted boat will not flood and sink. The water ballast is also much easier to contain structurally, compared with lead.
Boats only capsize under the most violent action of wind and water.
Resistance to these forces requires dynamic stability as well as static stability. Dynamic stability determines how quickly the boat will responds to a wind gust or wave action. A wind gust or steep wave can introduce very large forces, and a light weight boat will pitch or roll violently, increasing the probability of a capsize. Dynamic stability can be increased by moving heavy components away from the center of the boat. The bottom line is that a water ballasted twin keel design can have much more static and dynamic stability than traditional multi or mono hulls.