  We study the Lyapunov stability of a family of nongeneric equilibria with
spin for underwater vehicles with noncoincident centers. The nongeneric
equilibria belong to singular symplectic leaves that are not characterized as a
preimage o a regular value of the Casimir functions. We find an invariant
submanifold such that the nongeneric equilibria belong to a preimage of a
regular value that involves sub-Casimir functions. We obtain results for
nonlinear stability on this invariant submanifold.
