What must be done if approaching a vessel with restricted visibility?

When approaching a vessel in restricted visibility, sounding the horn as a warning is crucial for safety. This practice is part of the International Regulations for Preventing Collisions at Sea (COLREGs), which emphasizes the importance of communicating intentions in low-visibility conditions. Sound signals alert nearby vessels to your presence and can help prevent collisions, as visibility is limited and other navigators may not see your craft.

Other actions such as increasing speed to pass quickly might increase the risk of collisions, as the reduced visibility makes it harder to assess the distances and speeds of the vessels involved. Maintaining the same course without signaling may not adequately inform other vessels of your actions, which is especially important in reduced visibility scenarios. Preparing to anchor immediately may be necessary in certain situations, but it does not specifically address the need for communication with other vessels. Therefore, sounding the horn is the most appropriate and proactive measure to take when approaching another vessel in conditions of restricted visibility.