About 20% of maritime accidents involving small boats are caused by engine trouble. If the main engine stops under stormy conditions, then the operator might lose control of the boat, which might then overturn. In the worst case, such accidents can lead to injury and death. A main reason for sudden engine stoppage is that air bubbles form in the fuel line. That hazard has persisted as an important problem for small boats for many years. The present situation is that no decisive or effective countermeasure has been taken for boats. Some preliminary experiments were conducted to elucidate how air bubbles in the fuel line can be prevented when the boat rolls and pitches on the ocean. This research presents specific measures to prevent maritime accidents related to small boats.