Aim
Aim: To find out course of movement of a vessel, distance between two positions and time taken to reach from one position to another. Learning Outcome: At the end of this practical the student will be able to calculate course, distance and travelling time of a vessel. Materials Required: Parallel ruler, divider, pencil 1. Fix two different positions in a given chart. Mark the first position as ‘A’ and the second position as ‘B’ 2. Find out latitude and longitude values for both the positions 3. Connect the positions A and B with a straight line 4. Transfer the straight line connecting positions A and B to the nearest compass rose with the help of parallel ruler 5. When the edge of parallel ruler touching the centre point of compass rose, read the degree value on the compass rose in the direction of movement of position A to B. This reading of compass rose is course of movement of a vessel from the position A to B.(If you want to take the course of movement from the position B to A, the value of opposite side in the compass rose must be taken).Mark the course value just above the straight line connecting positions A and B.(All the angular values on the chart are TRUE values, unless they are specified) 6. By using divider, the distance between two positions A and B is measured with latitude scale ( Note: For distance measurement always use latitude scale and 1 minute on latitude scale is equal to 1 nautical mile.) Note: If the distance to be measured is greater than the maximum spread of the dividers put a convenient measurement on them from the latitude scale such as 10,15 or 20 miles, and measure off these units along the course line. The final short leg can be measured separately and added to the distance already measured. Study the following chart examples of a course and distance between two points. 7. Calculate time taken to reach position B from position A, with the given speed of a vessel (Note: Care must be taken when converting the hours ,minutes and seconds) Observation: True course from position A to B = o True course from position B to A = o Distance between position A to B = nautical mile Time taken to reach position B from position A= hrs. min. sec. |