In this paper, we present a mechanical design of a conceptual hybrid autonomous underwater vehicle (H-AUV) which combines the features of both a propelled underwater vehicle and those of an underwater glider. We develop its dynamic model and perform several simulations to showcase its locomotive capabilities. The main contribution of the paper is in the proposed motion planning technique to solve for trajectories from a start to a goal configuration. Our method generates feasible trajectories by integrating two Dubins curves. In fact, the motion planning technique is devised to not only generate feasible trajectories but also to assess the optimality of the proposed trajectories.