Question 312Navigation General

The correct answer is A. Under the IALA Buoyage System, a safe watermark will display the topmark shown in illustration D023NG, which is a single black sphere. This topmark indicates that the buoy or marker is on the safe water, meaning it is in the middle of the navigable channel or fairway. The other options are incorrect because B is a double black sphere (indicating a bifurcation or channel junction), C is a single black cone (indicating a port-hand mark), and D is a single black cylinder (indicating a starboard-hand mark). These topmarks have different meanings and are used to mark different types of navigational features.