Charts

Question 1

What are the first things you would do looking at a chart?

Answer 1

1. Make sure its up to date
2. Read notes
3. Read source data
4. Read datum
5. Read warnings

Question 2

How would you check a chart is up to date? How would you do a chart correction?

Answer 2

1. Look it up in the cumulative NTM
2. Make sure its the most up to date edition
3. Make sure the latest correction in the cumulative NTM is up to date
4. Check all subsequent weekly NTM after the cumulative NTM
5. Apply correction in magenta
6. Log correction on chart and NP133A

Question 3

How would you check a publication is up to date?

Answer 3

1. Check the Annual Summary NTM Part 2
2. Check all subsequent weekly NTM
3. Apply corrections
4. Record them in the books

Question 4

What are Ts and Ps?

Answer 4

A temporary NTM is a temporary addition or removal from chart, i.e wreck mark

A preliminary NTM gives you a prior warning to changes

Question 5

Where can you find Ts and Ps?

Answer 5

Annual summary NTM Part 1 and subsequent weekly NTM

Question 6

What is a mercator projection?

Answer 6

A rhumb line cuts all the meridians at the same angle

Question 7

What is a gnomic projection used for and how would you use it?

Answer 7

Ocean navigating

1. Straight line A-B
2. Add WPs (every 15°)
3. Transfer WPs to a mercator projection (which where they will appear as a curve)

Question 8

What is great circle?

Answer 8

The shortest route between A & B on the earths circumference

Question 9

What numbers are there in a wind rose

Answer 9

Number of observations
Percentage of variable winds
Percentage of calms