What device must gasoline engines installed in vessels after April 25, 1940 have?

Gasoline engines installed in vessels after April 25, 1940, are required to have a backfire flame control device. This requirement is significant for safety because a backfire can occur in the engine compartment and pose a serious risk of fire or explosion. The backfire flame control device is designed to prevent flames from escaping the engine compartment, which can protect both the vessel and its occupants from potential hazards.

This safety feature plays a crucial role in preventing ignition of volatile gasoline vapors that may be present in the engine area. By adequately containing any backfire that may happen, vessels equipped with this device can maintain a safer operating environment, especially considering that many boating accidents are linked to fuel system and engine issues.

While other options such as an emergency shut-off switch and fire suppression systems are also important for boating safety, the specific requirement for a backfire flame control device pertains directly to managing the risks associated with gasoline engines and their propensity for creating hazardous conditions in the event of engine failure or malfunction.