110+ Free SAMSA Skipper Category C (Coastal, up to 15 nm) Exam (South Africa) Practice Questions

Explanation: To obtain a compass course from a true course plotted on a chart, one must account for magnetic variation (the difference between true north and magnetic north), magnetic deviation (the error induced by the vessel's own magnetic fields), and leeway (the sideways movement of the vessel caused by wind). All three factors influence the actual course made good relative to the compass reading. Set and drift relate to the actual path over ground, not the course steered relative to the compass.

Explanation: A single-flashing light (Fl) is a common characteristic for aids to navigation, indicating a light that flashes regularly with a period where the light is on for a shorter duration than it is off. This distinguishes it from occulting lights, where the duration of light is longer than darkness, or fixed lights, which are continuous. The exact period (e.g., Fl 5s) would be specified next to the symbol on the chart.

Explanation: Radar uses radio waves to detect objects and display their range and bearing on a screen, making it indispensable in restricted visibility for collision avoidance and navigation. While AIS provides identity and course information from other vessels, it relies on them having an operational AIS transponder. A depth sounder measures water depth, and a magnetic compass provides heading, neither directly detecting other vessels' positions relative to yours.

Explanation: The IALA Maritime Buoyage System 'A' (and 'B') provides a universal system for marking navigable waters. Its primary purpose, especially for lateral marks, is to indicate the port and starboard sides of channels. In System 'A', when approaching from seaward in the conventional direction of buoyage, port hand marks are red and may have a can shape, while starboard hand marks are green and may have a cone shape. This convention guides mariners through channels and along coasts.

Explanation: In IALA System A, when proceeding in the conventional direction of buoyage (generally approaching from seaward), green conical buoys mark the starboard side of the channel. Therefore, a vessel should keep such a buoy to its starboard side to remain in the safe water of the channel. Red can buoys would mark the port side.

Explanation: Variation is the angular difference between true north (the geographical North Pole) and magnetic north (the direction to which a compass points due to the Earth's magnetic field). This value differs geographically and changes slowly over time, requiring correction when converting between true and magnetic bearings/courses. It is distinct from deviation, which is specific to the vessel.

Explanation: A running fix is a technique used when only one navigational object (like a lighthouse or prominent headland) is available. It involves taking a bearing to the object at an initial time, plotting that position line, and then, after a period of time has passed and the vessel has moved, taking a second bearing to the same object. The first position line is then 'advanced' parallel to the vessel's course and distance run, and where the advanced position line intersects the second position line is the vessel's estimated position at the time of the second bearing.

Explanation: South Africa adheres to the IALA System A buoyage. In System A, when entering a harbour or proceeding in the conventional direction of buoyage (from seaward), red lateral buoys mark the port side of the channel and should be kept to your port side. Green lateral buoys mark the starboard side of the channel and should be kept to your starboard side. This ensures a consistent navigation system for mariners.

Explanation: A depth sounder (or echosounder) is a crucial navigation instrument that uses sonar to measure the vertical distance from the bottom of the vessel's keel to the seabed. This information is vital for avoiding groundings, especially in shallow coastal waters, and for confirming charted depths. It does not provide speed, distance to hazards, or position.

Explanation: Tidal stream (or tidal current) information is critical because it describes the horizontal movement of water, including its direction (set) and speed (drift). This directly impacts a vessel's actual course made good and speed over ground, potentially pushing it off course or significantly altering its arrival time. Failing to account for tidal streams can lead to navigational errors, especially in confined waters or during long passages. Tidal height data only refers to the vertical rise and fall of water.