A snap roll on a submarine is similar in its effect to a snap roll on an airplane. When rudder angle is applied at high speed, the submarine will snap roll into the turn due to the hydrodynamic forces acting on the sub’s rudder and sail. read more
Snap roll is the sudden heeling of the sub in a turn. It is caused by hydrodynamic forces that arise due to the asymmetric appendages (fairwater). I think that it first became an issue when submarines started going fast underwater and the out of plane hydrodynamic forces become much larger than the static righting moments. read more