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Navigation📚 Guide

Navigation Skills

Complete guide to merchant seaman navigation skills: celestial navigation, electronic navigation, ECDIS, radar, COLREGs, passage planning, and watchkeeping.

•By MerchantNavy.co Editorial Team•7 min read•0 words
navigation skills for merchant seamen

Navigation skills are the most critical technical competency for deck officers, combining centuries-old celestial techniques with cutting-edge electronic systems to guide vessels safely across the world's oceans. The STCW Convention mandates that all deck officers demonstrate proficiency in navigation, as errors in this domain account for approximately 25% of maritime casualties [IMO, 2023].

This guide provides a comprehensive overview of the navigation skills required for merchant seamen, from foundational principles to advanced electronic systems, passage planning, and watchkeeping practices.

Before You Begin

  • Prerequisite qualifications: STCW OICNW (Officer in Charge of a Navigational Watch) certification
  • Required equipment: Sextant, charts (paper and electronic), compass, radar, GPS, ECDIS
  • Key references: COLREGs 1972, IMO Resolution A.893(21) on Passage Planning, IHO S-57/S-100 chart standards
  • Estimated training time: 3–4 years at maritime academy plus 12 months sea service for full competency

Celestial Navigation

Celestial navigation is the traditional method of determining position using the sun, moon, stars, and planets. While GPS has replaced celestial as the primary navigation method, STCW still requires deck officers to understand and practice celestial navigation as a backup.

Key Techniques

  • Sight taking: Using a sextant to measure the altitude of celestial bodies above the horizon
  • Timekeeping: Recording exact UTC from the ship's chronometer for each sight
  • Position lines: Converting sextant readings into lines of position using nautical almanac data
  • Sun-run-sun: Determining position by taking morning and noon sun sights with noon latitude
  • Star sights: Taking multiple star sights during civil twilight for a fix
  • Polestar (Polaris) fixing: Using Polaris to determine latitude in the Northern Hemisphere

Why It Matters: GPS can fail due to jamming, solar storms, or equipment malfunction. Celestial navigation provides a completely independent backup that requires no external signals.

Electronic Navigation

Electronic navigation systems have revolutionized maritime navigation by providing instant position fixing, route planning, and collision avoidance. Every deck officer must be proficient in multiple electronic systems.

GPS and GNSS

  • GPS: US Global Positioning System, accuracy 5–15 meters
  • GLONASS: Russian equivalent, used in combination with GPS for redundancy
  • Galileo: European GNSS, operational since 2016
  • Differential GPS (DGPS): Shore-based correction signals for 1–3 meter accuracy
  • GNSS limitations: Signal blockage in high latitudes, susceptibility to interference, requirement for backup systems

Radar and ARPA

Radar is the primary tool for collision avoidance and navigation in restricted visibility. IMO requires all vessels over 300 GT to be fitted with at least one radar operating in the X-band (9 GHz) and S-band (3 GHz) frequency ranges.

  • Radar plotting: Determining the course, speed, and closest point of approach (CPA) of other vessels
  • ARPA (Automatic Radar Plotting Aid): Computerized target tracking and collision risk assessment
  • True motion vs relative motion: Understanding both display modes
  • Radar limitations: Sea clutter, rain clutter, shadow sectors, false echoes

ECDIS

The Electronic Chart Display and Information System (ECDIS) is the primary navigation tool on modern vessels. ECDIS replaces paper charts when installed on a vessel, and all SOLAS vessels are required to carry ECDIS.

  • ENCs (Electronic Navigational Charts): Official hydrographic office charts with updates
  • S-57 and S-100 standards: IHO chart data formats
  • Route planning: Creating, checking, and monitoring routes in ECDIS
  • Safety alarms: Depth contour, proximity to danger, and cross-track error alarms
  • Backup requirements: ECDIS must have an independent backup (paper charts or second ECDIS)

AIS

The Automatic Identification System (AIS) transmits vessel identity, position, course, and speed to other vessels and shore stations. AIS is mandatory on all vessels over 300 GT on international voyages.

Passage Planning

Passage planning is the systematic process of planning a vessel's voyage from departure to arrival, considering all navigational hazards, weather, and regulatory requirements. IMO Resolution A.893(21) establishes the four-stage passage planning process.

Stage 1: Appraisal

  • Collect all relevant information: charts, publications, tide tables, weather forecasts, port information
  • Identify hazards: shallow water, wrecks, prohibited areas, traffic separation schemes
  • Assess vessel characteristics: draft, air draft, maneuvering characteristics

Stage 2: Planning

  • Select the optimal route considering safety, economy, and schedule
  • Mark waypoints, courses, and distances on charts
  • Identify wheel-over positions for course changes
  • Plan for alternative routes in case of weather diversion

Stage 3: Execution

  • Brief the bridge team on the passage plan
  • Monitor the vessel's position against the planned route
  • Update the plan as conditions change (weather, traffic, schedule)

Stage 4: Monitoring

  • Continuously verify position using multiple methods (GPS, radar, visual bearings, depth)
  • Monitor traffic using radar and AIS
  • Adjust the plan as necessary

COLREGs (Collision Regulations)

The International Regulations for Preventing Collisions at Sea (COLREGs) 1972 establish the rules for vessel navigation to prevent collisions. Every deck officer must have thorough knowledge of all 41 rules.

Key Rules

  • Rule 5 (Lookout): All vessels shall maintain a proper lookout at all times
  • Rule 6 (Safe Speed): All vessels shall proceed at a safe speed at all times
  • Rule 7 (Risk of Collision): Use all available means to determine if a risk of collision exists
  • Rules 11–18 (Steering and Sailing Rules): Rules for vessels in sight of one another
  • Rule 19 (Conduct in Restricted Visibility): Rules for navigation when visibility is restricted
  • Rule 34 (Maneuvering Signals): Whistle signals and light signals for maneuvering

Watchkeeping

Watchkeeping is the practical application of all navigation skills during routine vessel operations. STCW Chapter VIII establishes watchkeeping standards.

Bridge Watchkeeping Duties

  • Maintaining a proper lookout by sight and hearing
  • Monitoring the vessel's position, course, and speed
  • Monitoring traffic using radar, AIS, and visual observation
  • Operating communication equipment (VHF, GMDSS)
  • Maintaining the navigational logbook

Handover Procedures

  • Current position, course, and speed
  • Traffic situation and any developing risks
  • Navigational hazards ahead
  • Weather conditions and forecasts
  • Any equipment malfunctions or restrictions

Frequently Asked Questions

Can GPS replace celestial navigation?

GPS has largely replaced celestial navigation for routine position fixing, but STCW still requires deck officers to be proficient in celestial navigation as a backup. GPS signals can be disrupted by solar activity, jamming, or equipment failure.

What is the most important navigation instrument on a ship?

ECDIS is the most important navigation instrument on modern vessels, serving as the primary source of navigational information. However, radar remains critical for collision avoidance, and GPS provides position fixing.

How long does it take to learn navigation?

Basic navigation competency requires 12–18 months of study and sea service. Full proficiency as an OICNW requires 3 years of maritime academy education plus 12 months of sea service.

Do modern ships still use paper charts?

Ships fitted with ECDIS are not required to carry paper charts, but must have an independent backup. Many vessels carry paper charts as the backup system. Ships without ECDIS still rely on paper charts as the primary navigation method.

What is a passage plan?

A passage plan is a detailed voyage plan covering departure to arrival, including waypoints, courses, distances, hazards, weather considerations, and contingency plans. IMO Resolution A.893(21) requires passage planning for all vessels.

Conclusion

Navigation skills form the foundation of every deck officer's professional competence, combining traditional celestial techniques with modern electronic systems to ensure safe vessel operations. Mastery of passage planning, COLREGs, ECDIS, radar, and watchkeeping procedures is essential for career progression from Third Officer to Master Mariner.

References & Citations

  • [IMO, 2023] International Maritime Organization. "Maritime Safety Statistics 2023."
  • [STCW Code, 2010] International Maritime Organization. "Seafarer Training, Certification and Watchkeeping Code — Chapter II: Deck Department."
  • [IMO Resolution A.893(21), 1999] International Maritime Organization. "Guidelines for Voyage Planning."
  • [COLREGs, 1972] International Maritime Organization. "International Regulations for Preventing Collisions at Sea."
  • [IHO S-57, 2021] International Hydrographic Organization. "IHO Transfer Standard for Digital Hydrographic Data."
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