Virtual target-based path-following techniques are extended to execute the task of vehicle following in the case of unmanned surface vehicles (USVs). Indeed, vehicle following is reduced to the problem of tracking a virtual target moving at a desired range from a master vessel, while separating the spatial and temporal constraints, giving priority to the former one. The proposed approach is validated experimentally in a harbor area with the help of the prototype USVs ALANIS and Charlie, developed by Consiglio Nazionale delle Ricerche-Istituto di Studi sui Sistemi Intelligenti per lAutomazione (CNR-ISSIA).