According to Maritime Traffic Regulations for the Turkish Straits, "steering shall always be by hand" and "automatic steering devices shall never be used". However, it is considered that recent technological boost in computer science and control engineering opened this regulation to discussion; as today, automatic steering devices are a lot more safer. In this study, navigation of a 320m long ship through the Strait of Istanbul in autopilot mode was simulated. Ship motion equations are nonlinear and have three degree-of-freedom. Rudder was controlled by PD controller. Maximum speed of the ship during navigation was 10 knots as per traffic regulations. It was assumed that there was no current in Strait of Istanbul during ship's passage. Proportional and derivative gains were optimized by genetic algorithm. Simulation results show that the ship can safely voyage through the Strait of Istanbul in autopilot mode.