1. Nautical mile: For purpose of navigation. The distance on the Earth surface which represent 1 minute of latitude is as standard measurement at sea and is called a nautical mile (6080 feet).

2. True course: The angle between fore and aft line and the meridian through the position is called true course.

3. Knot: The speed of one nautical mile per hour is called a knot.

4. Pilotage: It is an art of conduction of a ship in the neighbourhood of dangers such as rocks and shoals and in the narrow waters such as harbour channels and canals.

5. Meridian: These are semi great circle joining the poles and are perpendicular to the equator.

6. Latitude: The latitude of a place is the angular distance of the place North or South of the equator.

7. Navigation: It is the art of finding the position of a ship at sea and conduction her safety from one place to another.

8. Equator: The great circle midway between the poles is known as the equator. Every point on the equator is therefore 90 degrees from the poles.