Cavity-wall interactions play an important role in determining the dynamics of supercavitating vehicles. To date, supercavitating vehicle system models make use of constant cylindrical cavities. As a further step, in this work, a dive-plane model with noncylindrical and nonsymmetric cavity shapes is developed. Cavitator angle of attack effects are considered, and a noncylindrical planing force model is incorporated. The system dynamics is examined in terms of nonlinear instabilities and the tail-slap phenomenon, and it is shown that the cavity shape plays a critical role in determining the system dynamics. The effectiveness of feedback control strategies with fin and cavitator inputs to achieve vehicle stability is also discussed.