What is the recommended action if a vessel becomes unable to maneuver?

The recommended action if a vessel becomes unable to maneuver is to display proper signals for being "not under command." This is essential as it alerts other vessels in the vicinity that your vessel is incapable of taking the necessary actions to steer or navigate safely. By doing so, you're complying with the International Regulations for Preventing Collisions at Sea (COLREGs), which mandate that vessels not under command must exhibit specific day shapes and nighttime lights to signal their status.

Displaying the correct signals not only helps to prevent collisions but also informs other mariners to take precautionary measures when navigating near your vessel. This communication is crucial in maintaining overall safety on the water.

Increasing speed to alert nearby vessels is not advisable in this situation, as it could lead to further loss of control and confusion among surrounding vessels. Similarly, turning on navigational lights only at night is not sufficient to communicate your status, as the signals must be visible at all times when the vessel is not under command. Additionally, while anchoring may be a prudent decision depending on the specific circumstances, it is not the immediate action that addresses the need to communicate the vessel's inability to maneuver. Therefore, displaying the proper signals is the most effective and required response.