Shelley Johnson, The Sea kayaker's Handbook(Camden: Ragged Mountain Press,2002), p. 24.

(The) discussion of cross sections brings us to the notion of stability in your boat. Kayakers traditionally speak of two kinds of stability: initial and secondary. Initial stability is how solid and stable your boat feels as you sit upright and at rest in the water. The flatter the bottom and wider the boat, the greater the initial stability of the boat. Initial stability is a comment on the "tippiness" of a given boat. Secondary stability, sometimes called reserved or ultimate stability, is how stable the boat is as it nears capsizing. Think of secondary stability as how strongly the boat fights capsizing once it begins to tip towards its side or shoulder.

Stability is also affected by the paddler's center of gravity and how the boat is loaded. If you lower your seat, stability will increase, since your center of gravity is lower. Just be sure you can still reach the water and paddle effectively. Uneven loading of your boat or placement of heavy objects on deck or toward the ends may decrease the stability. When paddling in rough seas, be sure that most of the weight is as close to the centerline and amidships as possible.

You can see that many factors affect the stability of a given boat. Boat specifications, such as width, can be less important than weight distribution. Some men with wide shoulders who carry a lot of their weight high find a particular boat tippy, while women of the same weight who carry a lot of their wieght low in the hips and thighs feel reassured in the same boat.