Navigation Basics

The basics?

Knowing the symbols on a nautical chart is the first place to start. This means you know what you are looking at. You can download the Canada chart symbol guide here
and the USA chart symbol guide here
You will note that symbols are mostly the same between all countries and this makes it easier when travelling from one to the next. For the entry level navigator you can lay the chart out on deck orientated in the same way the boat is in the real world. Then you can look at your compass to line up for land marks comparing between both the chart and what you see around you. It is important to allow Magnetic variation on the chart as this will change between one area and another as the angles between magnetic and true north change. Additionally this will change year to year as well as time goes by. To fix your position on the chart you need to line up at least two land marks in the real world with your boat and measure the angle (also called taking transits). Then draw these on to the chart. Where these two lines intersect is your location. Note the more transits you take will average out the error in each of the individual transits as there will become a cluster of intersections showing your approximate location. See the example below (from http://www.working-the-sails.com/).


How the basics have changed

The basics has changed significantly with the advent of GPS chart plotters and satellite technology. One of the the hidden risks of this technology is that many people no longer keep a log book or mark on a paper chart where they are. If you know where you are then you can find out how to find your way home. In the case of many coastal sailors this is sufficient as a backup in case the GPS stops working. You can use "dead reckoning" to find your way back to land in the coastal environment.

Know where you are

Keeping a log of coordinates or marking the passage on charts is the best way to track your position. However this only works well if it is done on some regular time interval. This is required more often for longer voyages especially where you maybe out of site of land. In the modern age you can just cheat so to speak and copy this information off the chart plotter.

What is "dead reckoning"?

This is basically the art of guessing where you are and where you are going at sea. It most often uses boat speed, heading and current combined with knowledge of your last known position to figure out where you are. In the case of the average coastal sailor it can be as simple as I can't see land but I know it is to the west of me so I will sail that way until I see land and then look for landmarks to figure out more accurately where I am.


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