Identify a common shape for port lateral buoys.

Port lateral buoys are designed to guide vessels safely through channels and into ports, indicating the safe side to leave when navigating. The common shape for these buoys is cylindrical. This shape is practical for a few reasons: it provides stability in water, allowing these buoys to remain upright even in rough conditions. Moreover, the cylindrical shape is easily recognizable and allows for quick identification by mariners, which is essential for safe navigation.

The ability to paint these buoys in distinctive colors, typically red, further enhances visibility and recognition. The design also accommodates necessary features like reflective surfaces or lights which improve their visibility at night and in poor weather conditions. All of these factors contribute to the effectiveness of cylindrical buoys in fulfilling their purpose within the IALA maritime buoyage system, ensuring safe passage and clear navigation for vessels.