Question 4Navigation General

The correct answer is A) square topmark. Under the IALA-A Buoyage System, a buoy indicating the preferred channel to starboard when entering from seaward will have a square topmark. This is because the preferred channel is to the right (starboard) side, and the square topmark is the standard shape used to mark the preferred channel in this system. The other options are incorrect because: B) a conical shape is used to mark the preferred channel to port; C) a long-flashing light characteristic is not a specific requirement for this type of buoy; and D) a green light is the color used for a buoy marking the preferred channel, but it does not define the shape of the topmark.