Navigation and Chartwork Flashcards
6 cards from real SVOP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Navigation and Chartwork flashcards as text
What is the difference between True North, Magnetic North, and Compass North?
Answer: True North is the geographic North Pole; Magnetic North is where the compass points (varies by location due to declination); Compass North is the actual compass reading (affected by magnetic deviation from the vessel)
True North: geographic pole (grid/chart north). Magnetic North: where the compass needle actually points (differs from True by declination/variation, which changes by location and year). Compass North: what your specific compass reads (differs from Magnetic by deviation caused by the vessel's metal and electronics).
On a nautical chart, what do contour lines (depth contours or isobaths) represent?
Answer: Lines connecting points of equal water depth, helping mariners identify shallow areas, underwater ridges, and safe water routes
Depth contours (isobaths) connect points of equal depth below chart datum (lowest normal tide level). They help mariners identify the shape of the seabed, locate shoals and banks, determine safe draft clearance, and plan routes away from hazards.
What is a 'range' or 'transit' in coastal navigation?
Answer: When two charted objects (lights, towers, beacons) are observed in line with each other, providing a precise position line
A range (or transit) occurs when two known charted objects align visually. The observer must be on the line through those two objects, giving a precise position line (LOP). Charted leading lights or marks are specifically placed to guide vessels along safe channels.
What is the purpose of a 'DR plot' (Dead Reckoning plot) on a nautical chart?
Answer: To estimate the vessel's current position by projecting from the last known fix using course, speed, and elapsed time
Dead Reckoning (DR) is the practice of advancing a known position forward by applying the vessel's course and speed over time. It provides an estimated position when GPS is unavailable or needs to be confirmed by other means.
What does a lateral buoy with a red triangular topmark indicate in the IALA 'B' buoyage system used in Canada and North America?
Answer: A starboard-hand mark — keep it on your starboard (right) side when proceeding from sea into harbour (returning)
In the IALA Region B system (Canada, USA, Japan), red marks with even numbers are kept to starboard when returning from sea ('Red Right Returning'). Green marks with odd numbers are kept to port. The triangular topmark confirms it is a starboard-hand (red) mark.
What is a 'Cardinal Buoy' and what does a north cardinal mark indicate?
Answer: Cardinal marks are placed to indicate safe water lies on the named cardinal side of the mark — a north cardinal indicates safe water to the north of the hazard
Cardinal marks are yellow and black buoys placed near hazards, indicating that the safest water lies on the named cardinal side. A north cardinal mark: safe water is north of the buoy. Pass to the north of it.