How To Competently Navigate

Below are some resources necessary if you're struggling. Including the official videos from the Royal Marines, those boring nav lectures.

A link to the full playlist

RM Map Reading Videos

No.1 Map Basics What they are and why they are used etc. No.2 understanding grid references No.3 how to use compass and protractor No.4 Measuring distances on a map No.5 how to orientate your map No.6 GMA Grid magnetic angle No.7 How to get a mag bearing No.8 how to get a back bearing No.9 grid bearings - how to plot them and use compass on a map No.10 Resections No.11 Marching on bearing using compass No.12 Creating route cards No.13 Folding maps

Measuring Distance Using Pythagorean Theroem

Fancy way of saying we'll measure a distance between two grids, just using maths.

To simplify what we are doing a bit to not blow minds, this is what we need to do:

a2 + b2 = c2
eastings2 + northings2 = distance2

Our distance is C in that equation. To get C we need to follow the equation. A squared plus B squared will give us C squared, to get C (our distance) we need to square root C squared.

Method

Example Grids: sx1234 5678 sx8765 4321

  • Minus your eastings. Take the smallest eastings away from the largest: 8765-1234 = 7531
  • Minus your northings. Take the smallest northings away from the largest: 5678-4321 = 1357
  • Square both of the above results: 75312 AND 13572
  • Add both of the squares together 75312 + 13572 = 58557410
  • Now you will be left with C squared
  • Square root your answer: √ans to get C
  • √58557410 = 7652
  • With your square root answer, multiply it by ten to get your distance
  • 7652 x 10 = 76520m

To Note: this won't work with grids in different grid squares so only use this formula on grids in the same grid square. E.g. sx to sy will not work sx to sx will sy to sy and so on. I'll update this once I find the extra maths to make this work on different grid squares

Extra Tips When Navving

  • When measuring distance break your maths down:
  • 1:25 maps 1mm:25m on the map
  • 1:50 maps 1mm:50m on the map
  • To remember this write it somewhere where the info won't perish e.g. small laminated sheets
  • Prime your compass night vision with a head torch before going out if night navving
  • Shine a torch / light source onto the compass and this will make the night vision components more pronounced for a short while