100+ Free BD Deck Officer Class 1 (Master) Practice Questions

Explanation: The Mercator projection expands meridian spacing with latitude so that rhumb lines (constant true course) plot as straight lines. A great circle is the shortest distance between two points on a sphere, and on a Mercator chart it plots as a curve bowed towards the nearer pole, which is why great circle routes are transferred to a Mercator chart as a series of rhumb-line legs.

Explanation: The vertex of a great circle is the point of maximum latitude reached along the track; beyond the vertex, the track's latitude decreases again. Composite great circle sailing is used specifically to limit a track from reaching an undesirably high-latitude vertex, such as one that would carry a ship into ice.

Explanation: Composite great circle sailing combines two great circle arcs tangent to a chosen limiting parallel of latitude, so the ship's track never exceeds that latitude. It is commonly used on high-latitude ocean routes, such as across the North Atlantic or North Pacific, to keep the vessel south of a limiting latitude chosen to avoid ice while still saving distance compared with a rhumb-line track.

Explanation: The relationship is LHA = GHA minus west longitude, or LHA = GHA plus east longitude. This follows from the convention that hour angle is measured westward from the observer's meridian, so an observer west of Greenwich has already had the body pass a smaller hour angle relative to their own meridian than the Greenwich value shows.

Explanation: Sun-Run-Sun takes a forenoon sun sight position line and transfers ('runs it up') to noon using the ship's course and speed made good, then combines it with the latitude obtained from the meridian altitude at local apparent noon (Mer Pass) to fix the noon position. It remains a useful offshore backup technique for a Master when electronic position fixing is degraded.

Explanation: For the sun, parallax in altitude is added to the sextant altitude because the sun's finite distance means an observer on the Earth's surface sees it at a slightly lower altitude than a hypothetical observer at the Earth's centre would; this correction is largest near the horizon and negligible near the zenith. Deviation, variation and gyro error are compass corrections, not sextant altitude corrections.

Explanation: The four recognized stages of passage planning are appraisal (gathering all relevant information), planning (deciding the intended track), execution (carrying out the plan, taking contingencies into account) and monitoring (continuously checking progress against the plan and taking corrective action). A Master is expected to ensure all four stages are properly carried out and documented before and during a voyage.

Explanation: STCW, and the corresponding DoS-adopted principles for keeping a navigational watch, place ultimate responsibility for the ship, cargo, crew and passengers with the Master at all times. The officer of the watch carries delegated responsibility for the safety of navigation while actually on watch, but this never relieves the Master of overall accountability, and taking a pilot on board does not transfer that ultimate responsibility either.

Explanation: Ship reporting systems, whether mandatory or voluntary, exist to give coastal states and vessel traffic services the information needed to support safety of life at sea, efficient navigation, and protection of the marine environment; a Master must know when and how to comply with any reporting system that applies along the intended route.

Explanation: The expanding square search is normally flown or sailed by a single search unit around a fairly accurately known datum, expanding outward in a square spiral at a defined track spacing; it is best suited to a relatively small, well-defined search area. Sector searches suit less precisely known datums, and parallel track (creeping line) searches suit larger areas or multi-unit coordination.