Charts

Question 1

Mercator Projections

Answer 1

A line which cuts all the meridians at the same angle is called a Rhumb line. Rhumb line are straight and cut the meridians at the same angle.

Question 2

Gnomic Charts

Answer 2

Cannot be used as a navigational chart.

Question 3

How to make Great circle

Answer 3

Use a gnomic chart draw straight line as desired great circle. Pick way points equally spaced in degrees. Take coordinates of waypoints and then transfer to Mercator projection chart. Will appear arced. Distance between way points is equally spaced in degrees on the hour over the full passage (e.g 12hours - 15 degrees)

Question 4

How to find a range using a sextant?

Answer 4

Take a bearing of object to get position line.
Use sextant to get an observed angle.
Correct for index error.
Find its height of object from the chart measured MHWS.
Go into Norris’s to the VSA table and get a range off.
Range and Bearing work out a positional fix.

Question 5

What about Height of Tide with VSA?

Answer 5

Reading Norries in prep for exam I read because it is MHWS you are on safe side. It will give closest possible range.

Question 6

Adjust the sextant for index error

Question 7

What is a PI?

Answer 7

It is a way of continuously monitoring our position. Not used for fixing our position.
It can back up and confirm a gps position.