The quality in a vessel that enables her to resist, and to recover from, a heeling force – usually ballast or weight in the keel. Small open boats can be unstable, whereas larger, decked boats nearly always have ample stability. There are two different types of stability: ‘initial stability’ and ‘ultimate stability’. A wide-bottomed vase with a heavy base will have good Initial stability, but a narrow-bottomed vase which is rather top heavy will have low initial stability. But even though the beamy and well-ballasted one will resist being toppled, neither will right itself when once laid flat: neither has ‘ultimate stability’. The toy clown with rounded and weighted base has all the Ultimate stability you could ask for – he always comes back up when knocked down. Yet the clown has low initial stability because it is quite easy to tilt him the fIrst few degrees. He heels more easily than the broad, ballasted vase. Boats may have either kind of stability, or a mixture, depending on their beam, their shape, and their ballast. In ordinary speech a boat with high initial stability is said to be Stiff. The converse is Tender.