Navigation and Chartwork Flashcards

When operating a vessel in Canadian waters, which are part of IALA Buoyage System Region B, what is the correct action to take when returning from sea and encountering a green, can-shaped buoy?

Answer: Keep it on your port (left) side.

In IALA Buoyage System Region B, which includes Canada and the Americas, the rule is 'Red, Right, Returning'. This means when returning from sea (upstream), red buoys should be kept on your starboard (right) side. Consequently, green buoys must be kept on your port (left) side.

You are plotting a course on a nautical chart. The compass rose indicates a variation of 15° West. Your vessel's deviation for the intended heading is 3° East. To convert a true course of 100° (T) to a compass course (C), what is the correct calculation?

Answer: 100° (T) + 15° (W) - 3° (E) = 112° (C)

To convert from a True course to a Compass course, you must account for both variation and deviation. A common mnemonic is 'True Virgins Make Dull Company, Add Whiskey' (True, Variation, Magnetic, Deviation, Compass, Add West). When going from True to Compass, you subtract easterly errors and add westerly errors. Therefore, the calculation is: 100° (True) + 15° (West Variation) = 115° (Magnetic). Then, 115° (Magnetic) - 3° (East Deviation) = 112° (Compass).

Which of the following symbols on a Canadian Hydrographic Service (CHS) chart represents a rock that is submerged but has a depth of 2 meters or less over it, making it a significant danger?

Answer: A plus sign (+)

According to Canadian Hydrographic Service's Chart 1, a plus sign (+) symbol is used to denote a rock that is submerged at chart datum and has a depth of 2 meters or less over it. An asterisk (*) represents a rock that uncovers (is visible) at low tide.

While navigating in coastal waters, you take bearings on two prominent, charted landmarks to determine your vessel's position. The first bearing is on a lighthouse at 310° and the second is on a water tower at 220°. What is this method of position fixing called?

Answer: A cross bearing fix

A cross bearing fix is a method of determining a vessel's position by taking bearings on two or more fixed, charted objects. The intersection of these lines of position on the chart indicates the vessel's location.

Which of the following is NOT typically found in the title block or marginal notes of a Canadian nautical chart?

Answer: Real-time vessel traffic information

A nautical chart's title block and marginal notes contain essential static information like the scale, projection, units for depths and heights, and the reference datum. Real-time information, such as live vessel traffic, is dynamic and obtained from systems like AIS (Automatic Identification System), not printed on the chart itself.

On a nautical chart, 'Variation' is the angular difference between:

Answer: True North and Magnetic North

Variation (also known as magnetic declination) is the angle between True North (the geographic North Pole) and Magnetic North (the direction a compass needle points). This value changes based on geographic location and is indicated on the chart's compass rose.