Navigation is the art and science of determining a vessel’s position and directing her safely from where she is to where she needs to be. For the beginner it means three questions: where am I, which way do I go, and what is in the way. For the experienced navigator it is a continuous discipline of planning, fixing, predicting and checking, carried on whether or not the electronics are working. The seasoned skipper’s addition is this: good navigation is less about knowing exactly where you are than about always knowing where you are not, so that a hazard can never surprise you. The chart plotter has made position-finding trivial, but it has not removed the need for a navigator who understands what the position means.
The Four Branches of Navigation
Sailors traditionally divide the subject into four methods, and a competent navigator uses all of them, often at once. Pilotage is navigation by reference to what you can see: compass bearings of landmarks, transits where two objects line up, depth soundings and buoyage. It is the method for coastal and harbour work and needs nothing beyond a hand-bearing compass and a chart.
Dead reckoning uses course steered, speed through the water and time elapsed to project a position forward from the last fix; add tidal stream and leeway and you have an estimated position, the honest best guess between fixes. Celestial navigation fixes position from the measured altitude of the sun, moon, planets or stars with a sextant, an accurate clock and an almanac; the noon sight for latitude is its simplest form. Electronic navigation covers GPS and the other satellite systems, radar, AIS and the electronic charts that combine them.
The Navigator’s Cycle
Whatever the method, the work follows a cycle. Plan the passage before leaving: courses, distances, tidal gates, hazards, ports of refuge and the points at which you will decide to turn back. At sea, obtain a fix by whatever means is available and plot it with the time. Run dead reckoning forward from it so you always have a predicted position. Compare each new fix with the prediction; the difference tells you about the current, the leeway or the helmsman. Correct the course and start again.
The log is the backbone of this cycle. Record time, position, course, speed and barometer at least hourly offshore and at every alteration of course; if the electronics fail, the log gives you a recent fix and everything needed to carry on. Underlying the plot is the distinction between heading, the direction the bow points; course to steer, the compass course that allows for tide and leeway; and course over ground, the track actually made good. Compass courses are converted from true to magnetic for variation and then corrected for the boat’s own deviation.
Cruising and Racing Perspectives
The cruising navigator’s priorities are safety and arrival. A passage plan built around tidal gates, daylight arrival and a margin of safe water is worth more than any instrument. Cruisers keep a paper chart open even when the plotter is doing the work.
The racing navigator has the same tools and a different question: not just where are we, but where should we be to gain on the fleet. Offshore, that means routing through the weather with polars and forecast models, timing tidal streams to the minute and choosing which side of a headland to favour. Inshore, the navigator becomes the tactician’s eyes for laylines, distance to the line at the start and the set of the current across the course. The skills are the cruiser’s; the tolerances are much finer.
Common Mistakes
- Single source of truth: trusting one screen with no cross-check against depth, a bearing or dead reckoning.
- Zoom errors: a plotter zoomed out hides rocks; zoomed in it hides the big picture.
- Ignoring the stream: a 2-knot cross-tide on a 5-knot boat puts you a mile off track every hour if you steer the chart course.
- No log: when the power fails, the last logged position is all you have.
Frequently Asked Questions about Navigation
Do I still need to learn navigation if I have GPS?
Yes. GPS tells you where you are; navigation tells you what that means and what to do about it. Electronics fail and signals can be jammed or spoofed, and a navigator who can plot a position, work a tide and run dead reckoning will get home when the screen goes dark.
What is the difference between navigation and pilotage?
Pilotage is the branch of navigation concerned with conning the boat by visual reference in confined waters. Navigation is the broader discipline that also includes offshore position-finding by dead reckoning, celestial observation and electronics.
How often should I fix my position?
Offshore, at least hourly in the log. Coastal, more often, and always before and after a course change or when approaching a hazard.
Navigation is the thread that ties every other seamanship skill together; see also pilotage, dead reckoning, fix, waypoint, bearing and nautical mile. Sail trim and boat handling get you moving; navigation makes sure the moving takes you somewhere safe and intended. Keep the plot going, cross-check everything, and the sea will hold very few surprises.