top of page
Lesson 3 - Distance, Depth & Height
Distance
At sea, distance is measured in nautical miles or meters.
Speed
Mariners measure speed using knots, where 1 knot equals 1 nautical mile an hour.
Charter Depths
- Spot Depth
- Contour Lines
- Drying line
Depth & Height
-
Chart Datum
-
Mean High Water Springs (MHWS)
-
Highest Astronomical Tide (HAT)
Measuring Depth in Practice
Echo sounders are the standard tool. They work by sending high-frequency sound waves to the seabed and measuring the time it takes for the echo to return. This time is then converted into a depth reading.
Dead Reckoning (DR)
Example:
-
Compass reading = 090
-
Distance Traveled in = 6 NM
bottom of page