Secondary stability

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Secondary stability, or reserve stability, is a boat’s ability to right itself after tipping to large angles. Primary stability is the tendency to stay upright at small tilts, usually less than about 10 degrees. These ideas are studied in naval architecture for small watercraft. Interestingly, making a boat wider (greater beam) and increasing its initial stability can reduce secondary stability: once the boat tilts beyond a certain angle, it can be harder to return to an upright position. This concept is especially important for kayaks, canoes, and other small boats.