Final answer:
Under GMDSS, all ships must be able to carry out essential communication functions for their own safety and the safety of other vessels. This may involve aiding other ships in distress, particularly when in areas not well serviced by shoreside authorities, such as sea areas A2 and A4.
Step-by-step explanation:
The responsibility of vessels under the Global Maritime Distress and Safety System (GMDSS) is to ensure that crucial communications are possible for the safety of the ship and other vessels. This involves several aspects. Vessels of over 300 gross tons may be obligated to assist if it doesn’t affect their port schedule unfavorably. However, the size of a ship doesn’t always determine the requirement of rendering assistance; sometimes the vessel closest to the one in distress, regardless of its size, is required to assist. Moreover, vessels operating under GMDSS, specifically in regions not effectively serviced by shore-side authorities - such as in sea areas A2 and A4, may have to provide assistance in distress situations.
Learn more about GMDSS responsibilities