Identify a common type of portable fire extinguisher onboard vessels.

A dry chemical ABC extinguisher is a common type of portable fire extinguisher found onboard vessels due to its versatility and effectiveness in combating different classes of fires. The designation "ABC" indicates that this extinguisher can be used on Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical) fires, making it suitable for various scenarios encountered on a ship. The dry chemical agent works by interrupting the chemical reaction of the fire, effectively smothering the flames and preventing re-ignition.

This type of extinguisher is favored in maritime environments because it can tackle a wide range of potential fire hazards, which are common in confined spaces and mixed environments of a vessel where multiple combustible materials and hazards may be present.

While carbon dioxide extinguishers are also effective for specific types of fires, particularly involving electrical equipment and flammable liquids, they have limitations. For example, they are not suitable for cooling burning solids effectively. Water-based extinguishers are primarily for extinguishing Class A fires and can pose risks in the presence of flammable liquids or electrical fires. AFFF extinguishers are primarily designed for flammable liquid fires, specifically Class B, and may not be as versatile as