DWO Chart Work and Pilotage

Question 1

What datum is used for soundings on US nautical charts?

Accepted Answer

Mean Lower Low Water (MLLW)

Answer

US nautical charts use Mean Lower Low Water (MLLW) as the chart datum for soundings, providing a conservative safety reference.

Question 2

What does blue tinting on a nautical chart typically indicate?

Accepted Answer

Shallow water less than the specified depth contour

Answer

Blue tinting marks shallow water areas on nautical charts, warning mariners of potentially hazardous depths.

Question 3

What does the abbreviation 'PA' printed next to a chart symbol mean?

Accepted Answer

Position Approximate

Answer

PA stands for Position Approximate, indicating the charted feature's location has not been precisely surveyed.

Question 4

On a nautical chart, a magenta circle with a dot in the center represents what type of navigational aid?

Accepted Answer

A fixed light structure such as a lighthouse

Answer

A magenta circle with a central dot indicates a fixed light structure on a nautical chart, such as a lighthouse or light tower.

Question 5

Which statement correctly describes a large-scale nautical chart?

Accepted Answer

It shows a small geographic area with greater detail

Answer

Large-scale charts (e.g., 1:10,000) depict a smaller geographic area with greater detail, making them ideal for harbor and coastal navigation.

(DWO) Deck Watch Officer Practice Test