A theoretical analysis is presented for treating the free vibrations of submerged, ring stiffened cylindrical shells with simply supported ends. The effects of the eccentric stiffeners are averaged over the thin-walled isotropic cylindrical shell. The energy method is utilized and the frequency equation is derived by Hamilton\u27s Principle. All three degrees of freedom are considered. Numerical results are presented for frequencies and mode separation for several cases of interest. Comparisons with previous theoretical and experimental results indicate good agreement. The cylindrical wave approximation and the plane wave approximation for the field equation were investigated. Their applicability was evaluated and the results indicate that only the cylindrical wave approximate method gives good agreement with the exact solution. For a steel shell in water with c = 5.82 slug/sec, the plane wave approximate method gives very poor results (about 5-20% accuracy
