What action must a give-way vessel take when necessary?

The correct action for a give-way vessel is to take early and substantial action to keep clear of the stand-on vessel. This is essential according to the COLREGs, which are designed to prevent collisions at sea by establishing a system of rules regulating maritime conduct.

When a vessel is identified as the give-way vessel, it has the responsibility to maneuver in a way that ensures safety. This action should be significant enough to create a clear indication of its intentions and to avoid putting the stand-on vessel in a position where it may have to take evasive action. The emphasis on "early and substantial" highlights the need for proactive measures, rather than reactive ones, which can contribute to clearer communication and safer navigation between vessels.

The other options do not meet the requirements set forth in the COLREGs. Waiting for the stand-on vessel to maneuver does not align with the obligation of the give-way vessel to take action. Additionally, signaling another vessel to slow down is not a necessary or required action and may not be effective in emergency situations. Finally, adjusting speed without changing course may not provide enough assurance that the give-way vessel will maintain a safe distance, thereby failing to uphold its duty to prevent collision effectively.