How should a vessel be prepared in terms of air flow before fueling?

When preparing a vessel for fueling, ensuring proper air flow is crucial for safety reasons. Opening all windows, ports, doors, and other openings allows fresh air to circulate throughout the interior of the vessel. This circulation helps to dissipate any potentially harmful vapors that could accumulate during the fueling process. By allowing these vapors to escape, the risk of an explosion or fire is significantly reduced, as gasoline vapors are heavier than air and can settle in low-lying areas.

In contrast, keeping windows shut tight or closing all openings can trap these dangerous vapors inside, creating an unsafe environment. Only opening the main hatch does not provide adequate ventilation, as it might not sufficiently allow vapor escape from other parts of the vessel. Thus, maximizing airflow by opening all relevant openings is an essential practice for maintaining safety during fueling operations.