Navigation & Charting Flashcards
7 cards from real MMC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Navigation & Charting flashcards as text
What does a yellow buoy or marker typically indicate in U.S. waters under the IALA-B system?
Answer: A special purpose mark such as a spoil area, anchorage, or traffic separation zone
Yellow buoys in the IALA-B (U.S.) system are special purpose marks indicating areas such as dredge spoil zones, anchorage areas, or traffic separation schemes.
Which type of chart projection preserves compass bearings as straight lines, making it ideal for navigation?
Answer: Mercator projection
Mercator projection displays rhumb lines (lines of constant compass bearing) as straight lines, making it the standard for nautical charts used in coastal and ocean navigation.
A light sector shown in red on a nautical chart indicates that within that sector the light:
Answer: Warns mariners of shoal water or a hazard in that direction
A red sector on a sectored light indicates that the light shows red in that arc, warning mariners that they are approaching shoal water, rocks, or another hazard.
When anchoring, a navigator uses 'scope' which refers to:
Answer: The ratio of anchor rode length paid out to the depth of water
Scope is the ratio of anchor rode (chain or line) deployed to the water depth; a scope of 7:1 (rode length to depth) is commonly recommended for good holding.
What is the meaning of 'chart datum' as used for soundings on U.S. nautical charts?
Answer: Mean Lower Low Water (MLLW), the average of the lower of the two daily low tides
U.S. nautical chart soundings are referenced to Mean Lower Low Water (MLLW), which is the average of the lower of the two daily low tides over a 19-year National Tidal Datum Epoch.
A navigator plots a fix using two cross-bearings and notes they intersect at a very small angle (nearly parallel). This fix should be considered:
Answer: Unreliable because a small error in either bearing shifts the fix significantly
When two LOPs intersect at a small angle (less than 30°), even a minor bearing error causes a large shift in the fix position, making the result unreliable; bearings should ideally intersect near 90°.
The U.S. Coast Pilot publication is most useful for which type of navigational information?
Answer: Supplemental information on anchorages, port facilities, channels, and local regulations not shown on charts
The U.S. Coast Pilot provides detailed supplemental information including port facilities, anchorages, channel descriptions, local hazards, and regulations that cannot be depicted on nautical charts.