The four classical methods
Navigation is the art and science of determining a vessel's position and directing its movement safely from one place to another. It is the oldest professional skill at sea and, despite complete technological transformation, the fundamentals have not changed: know where you are, know where the dangers are, and know where you are going.
| Method | Principle | Status today |
|---|---|---|
| Terrestrial | Bearings and ranges to identifiable landmarks | Core skill in coastal waters |
| Celestial | Sextant observations of sun, stars and planets | Taught as a backup; rarely primary |
| Dead reckoning | Position estimated from course, speed and time | Continuous; the sanity check on everything |
| Electronic | GNSS, radar, ECDIS | Primary in practice |
Dead reckoning deserves emphasis. A navigator who maintains a DR position knows immediately when an electronic fix is implausible. When GNSS is jammed or spoofed — an increasingly reported problem in several regions — DR is what prevents a fix error becoming a grounding.
The modern bridge
| System | Function |
|---|---|
| GNSS receiver | Position, from GPS, Galileo, GLONASS or BeiDou |
| ECDIS | Electronic chart display and information system; the primary chart on most vessels |
| Radar with ARPA | Target detection and automatic collision-avoidance plotting |
| AIS | Identity and intentions of other vessels |
| Gyro and magnetic compass | Heading |
| Echo sounder | Depth under keel |
| Speed log | Speed through water |
| VDR | Voyage data recorder — the evidential black box |
| Autopilot / track control | Course and track keeping |
Passage planning
SOLAS requires a voyage plan from berth to berth. The four recognised stages:
- Appraisal. Gather all information — charts, publications, tides, weather, port information, traffic schemes, hazards, company and charterer requirements.
- Planning. Lay off the intended track, with abort points, no-go areas, wheel-over points, under-keel clearance calculations and contingency anchorages.
- Execution. Sail the plan, adjusting for conditions, with the bridge team briefed.
- Monitoring. Continuous position fixing by independent means, cross-checking the primary system.
Passage plans that are approved without evidence of review are a recurring audit finding, and passage planning failures feature repeatedly in grounding investigations.
COLREG: the rules of the road
The International Regulations for Preventing Collisions at Sea govern conduct between vessels: lookout, safe speed, risk of collision, action to avoid collision, conduct in narrow channels and traffic separation schemes, responsibilities between vessels, and lights, shapes and sound signals.
Two rules do most of the work in practice:
- Rule 5 — Lookout. By sight, hearing and all available means. Investigations after collisions overwhelmingly find lookout failures.
- Rule 8 — Action to avoid collision. Positive, made in ample time, and large enough to be readily apparent to the other vessel. Small, late alterations are how close-quarters situations develop.
The GNSS dependency problem
Modern navigation depends on satellite positioning, and satellite positioning can be jammed or spoofed. Reported interference in several regions has made this an operational rather than theoretical concern.
Resilience measures:
- Maintain a continuous DR position and compare it with GNSS
- Cross-check with radar ranges and bearings to charted features
- Monitor echo sounder against charted depth
- Retain and practise terrestrial and celestial competence
- Treat sudden unexplained position jumps as suspect until verified independently
- Record and report interference
Bridge resource management
Navigation is a team activity. BRM addresses how the bridge team communicates, challenges and cross-checks: clear roles, closed-loop communication, the authority for any team member to raise a concern, and the master's availability. Many incidents involve a bridge team where someone knew something was wrong and did not say so effectively.
navigation requirements are set by SOLAS Chapter V and COLREG; consult the current instruments and flag state guidance. Contributory-factor chart is an indicative model based on published investigation themes. Reviewed by the Zeaclub Editorial Team, 24 August 2026.
Frequently asked questions
What is navigation in maritime terms?
Determining a vessel's position and safely directing its movement, using terrestrial, celestial, dead reckoning and electronic methods, in accordance with COLREG and an approved passage plan.
Is celestial navigation still taught?
Yes, as a backup competency. It is rarely used as the primary method but remains valuable when electronic systems are unavailable or untrusted.
What is ECDIS?
The Electronic Chart Display and Information System — the electronic navigational chart system that serves as the primary chart on most commercial vessels, subject to carriage and training requirements.
What happens if GPS fails?
The bridge reverts to dead reckoning cross-checked with radar, visual bearings and echo sounder. This is exactly why those skills remain in the training syllabus.