We study the problem of formation control and trajectory tracking for a group of fully actuated marine vehicles, in the presence of uncertainties and unknown disturbances. The objective is to achieve and maintain desired formation tracking, and guarantee no collision between the marine vehicles. The control development relies on existing potential functions which fall at a minimum value when the vehicles reach the desired formation, and blow up to infinity when the vehicles approach collision. The combination of the potential functions, backstepping and variable structure based design technique allows us to handle time varying disturbances by ensuring a stable formation. Using the sliding-Backstepping technique and Lyapunov synthesis, a stable coordination tracking controller is designed. Uniform boundedness of the closed loop signals system is achieved.