Which item should always be included in a vessel's safety equipment?

The inclusion of a throwable flotation device as a mandatory piece of safety equipment on a vessel is based on the need to provide immediate assistance to individuals who fall overboard or are in distress in the water. These devices are designed to be thrown to a person in trouble, offering buoyancy and preventing drowning until they can be rescued.

Given the unpredictable nature of boating, having a throwable flotation device on board enhances the safety of all passengers by ensuring that there is a means to assist someone quickly if needed. Other safety equipment, such as life jackets or personal flotation devices, are also crucial, but the specific role of the throwable device is to be readily accessible for immediate deployment.

In contrast, the other items listed do not address safety needs as effectively. An anchor, while useful in mooring the vessel, does not contribute directly to individual safety in emergencies. A rod and reel relate to recreational fishing but are not safety gear, and a cooler with food and drinks, while it can enhance comfort during a trip, does not fulfill any safety requirements. Thus, the importance of having a throwable flotation device lies in its direct application to saving lives and enhancing overall safety on the water.