The basics of a control framework for a class of underactuated vehicles immersed in an ambient fluid with the objective of stabilizing reference trajectories are developed. These vehicles are characterized by their means of propulsion which essentially relies on the production of a thrust force along a single body-fixed direction, with the complement of full torque actuation for attitude control (i.e. a typical actuation structure for aircrafts, VTOL vehicles, submarines, etc.). Interactions with the surrounding fluid are difficult to model precisely and the source of possibly strong perturbations. They constitute a major issue for stable motion control of these systems. Novel nonlinear feedback control laws are proposed to compensate for modeling errors and perform robustly against such perturbations. Simulation results illustrating these properties on a VTOL vehicle submitted to wind gusts are presented.