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→Roll Stability
Many displacement boats will self-right from 65-70 degrees before they turn turtle. Unlike sail boats very few have positive stability to 130 degrees.
A vessel’s stability can be divided into two performance categories: initial stability and ultimate stability.
Initial stability defines the angles of heel that are normal to a vessel's operation. This is also the [[#Static Stability|static stability]]. This is usually between zero and 15 degrees of heel. A wide-beamed boat heels less (has greater stiffness), and is more comfortable. But a narrower-beamed boat has more ultimate stability. Ultimate stability is the angle of vanishing stability.
The righting moment is a force generated by the righting arm (GZ). The righting arm is the transverse distance between the centre of gravity (CG) and the centre of buoyancy (CB).<ref>A Best Practices Guide to Vessel Stability, Guiding Fishermen Safely Into the Future, Second Edition, United States Coast Guard, http://www.uscg.mil/hq/g-m/cfvs/</ref> Hopefully this will become clearer as you read on.