This paper presents a simulation study of path following for the Heron Unmanned Surface Vehicle (USV) using a Line-of-Sight (LOS) guidance approach. The tests were performed on both straight-line and circular paths to evaluate the USV’s ability to converge to and track the desired trajectory. Simulations were conducted in the Robotic Operating System (ROS)–Gazebo environment, where the LOS algorithm was combined with a Proportional–Integral–Derivative (PID) controller to regulate heading and reduce cross-track error. Controller gains were tuned using the Ziegler–Nichols method and refined through manual adjustments, enabling stable and accurate turning performance. The results demonstrate that the PID-based LOS guidance method provides effective and reliable path following for underactuated USVs and other marine vehicles.