Sea Skills: Charts and Positions
In the Second World War, navigators spent hours bent over paper charts covered in lines, numbers and pencil marks. Those charts were their map of the war at sea. A single dot and a set of coordinates could show the position of a convoy, a minefield, or a suspected submarine.
Two of the most important ideas on a chart are latitude and longitude:
- Latitude tells you how far north or south you are from the Equator. On a chart, latitude lines run horizontally, but the numbers increase as you go up (north) or down (south). They are measured in degrees (°) and minutes ('), for example 50°01'N.
- Longitude tells you how far east or west you are from the Prime Meridian at Greenwich. On a chart, longitude lines run vertically, and the numbers increase as you go left (west) or right (east). They are also measured in degrees and minutes, for example 001°00'W.
By reading latitude and longitude together, you can give a position that is accurate to just a few cables or less – close enough in wartime to steer clear of mines, find a harbour entrance, or intercept a U-boat sighting.
Your mission: Convoy on the chart
Imagine you are a junior officer on a small escort vessel in 1943. The chart table in front of you shows a stretch of British coastal waters in a simple cartoon style: scribbled waves, a doodled harbour, and little ship icons for the convoy. Somewhere nearby, a suspected submarine contact has been reported.
Your job is to:
- Read the coordinates (latitude and longitude) given in your orders.
- Find the correct square on the chart and click it.
- Keep track of how many correct positions you can find in a row.
This is exactly the kind of basic chart work that kept real ships safe: plotting convoys, marking hazards, and making sure everyone was where they were supposed to be. Once you can read a chart, the sea stops being a blank blue space and becomes a detailed story you can understand.
Convoy Chart Game
Read the latitude and longitude, then click the correct square on the mini chart. North is up, east is to the right – just like a real chart.
Orders
A position has been reported on the chart:
Click “New position” to begin.
Tip: latitude numbers are shown down the left-hand side of the chart, longitude numbers along the bottom. Think “ladder” for latitude (climb up and down), and “long” for longitude (the long way round the Earth).
What you are looking at
- The chart is divided into squares that are 1 minute of latitude by 1 minute of longitude.
- Each square can hold a symbol: the convoy, your escort, a U-boat contact, a safe channel, or the harbour.
- In real life, navigators would also draw bearings, depth soundings and danger circles around hazards.
Challenge: once you find the convoy, imagine plotting a safe route from the harbour to join it, keeping clear of the marked danger area.
Mini WWII Convoy Chart
Think of this as a simple cartoon version of a real navigation chart. On a full Admiralty chart you would also see depth numbers (soundings), buoys, lighthouses and notes telling you where it is safe to anchor.