Navigation and Seamanship

Points to be considered during chart reading

1. Make a thorough reading of the chart including the cautions.

2. Latitude and longitude scales are divided into minutes and then tenths of minutes (seconds are not used on charts). So latitude may be written as 12°38.5' or 12°38’ 30”

3. When determining distances on the chart use only the latitude scale on the side of the chart.(one minute of latitude equals one nautical mile, i.e., 1.852 Kilometres)

4. Take care to read the chart details carefully and note whether soundings are in fathoms or metres.

 5. Angular degrees on chart is always true. A compass course is always magnetic. Be sure to take account of these two facts in your chart and navigation work. Conversions must be done correctly.

6. As the variation is not constant the charts will have more than one compass rose displayed.

7. Familiarize thoroughly yourself with graduations on the chart before reading the latitude and longitude.

8. Use only good quality pencil and soft erasers for chart work. Always keep the chart dry, keep bottles and pens away from the chart. ( Hard leaded pencils may damage the paper chart).

9. Look for the date of the latest information.

10. At the end of the chart work ,all pencil impressions should be neatly erased.