Sink drains that exit below the water line are required by ABYC to have what?

Sink drains that exit below the water line must have a seacock in order to prevent backflow and ensure safe operation. The presence of a seacock allows the drain to be closed off when not in use, which is crucial for preventing water from entering the vessel through the sink drain, particularly in rough weather conditions. This requirement is based on safety and the prevention of flooding inside the boat.

In contrast, options that suggest the drain could be exempt from seacock requirements or must drain into the bilge do not align with best practices for maintaining a safe vessel. A P-trap, though important for waste management and odor control, does not substitute the need for a seacock in this specific context. The seacock is essential for managing potential risks associated with sink drains located below the water line.