Read the aids before you reach them
Aids to navigation are most useful when the chart helps you understand them before they appear out of the darkness or background lights. SeaVectors portrays charted lights, colored sectors, directional beams, beacons, and buoys from their ENC attributes using familiar S‑52 conventions.
Instead of reducing every aid to the same pin, SeaVectors preserves the distinctions that matter: color, rhythm, period, sector limits, nominal range, buoy or beacon type, and the geometry of supported directional lights. Tap an aid to inspect the details available in the ENC.
Want to see the portrayal in a harbor you know?
The 30-day full-access trial gives you time to compare the chart with real aids in your own cruising area.
Show aids to navigation
Open the Layers panel and enable the Lights quick group. This brings the supported lights, beacons, and buoys into the chart together. Detailed Layers let you refine individual aid types or related portrayals when the view becomes crowded.
Aids and their labels are scale-dependent. Zoom into a harbor approach or channel before deciding something is missing.
Read Map Layers & Detail Control for the complete layer workflow.
Understand a light characteristic
A charted light characteristic is a compact identification code. It describes how the light behaves, its color, and its repeating period.
| Example | Meaning |
|---|---|
F W |
Fixed white light |
Fl G 4s |
Flashing green light; one cycle every 4 seconds |
Fl(2) R 10s |
Group flashing red, two flashes; 10-second period |
Oc W 6s |
Occulting white light; 6-second period |
Iso Y 2s |
Isophase yellow light, with equal light and dark intervals; 2-second period |
Q |
Quick-flashing light |
Common rhythm abbreviations include F (fixed), Fl (flashing), Oc (occulting), Iso (isophase), and Q (quick). The color may appear as R (red), G (green), W (white), or Y (yellow).
Use the complete rhythm, color, and period together. Several nearby lights may share a color but have different characteristics.
All-around lights and nominal range
An all-around light displays one color through the charted 360-degree arc. SeaVectors shows its flare, available label, color, and charted nominal range.
Nominal range is the distance at which a light is expected to be visible under defined meteorological conditions. It is useful for planning identification, but it is not a guaranteed physical boundary. Actual visibility changes with haze, rain, background lighting, observer height, the height and condition of the light, and the curvature of the Earth.
In the native SeaVectors app, light portrayal becomes more prominent as your vessel enters the light's charted nominal range. Distant aids remain part of the wider chart, while lights becoming relevant to the approach draw more attention. This range-aware behavior is especially valuable during night passages and busy harbor entries.
Sector lights and fixed beams
A sector light displays different colors over different bearing arcs. The sectors may indicate a preferred approach, mark the sides of a channel, or warn that a vessel has moved away from the intended water.
SeaVectors can portray supported sector information with:
- Red, green, white, or yellow arcs matching the charted sector colors
- Sector-boundary legs showing the limiting bearings
- Symbolic beams for very narrow sectors that would otherwise disappear at the current scale
- Directional or fixed beams where the ENC contains leading or alignment information
- Tap highlighting to make the selected sectors and supported fixed white approach area easier to inspect
A white sector is not automatically safe in every circumstance. Confirm what the particular light and chart intend, then consider depth, hazards, traffic, tide, visibility, and your vessel's limitations. Never steer solely by screen color.
Buoys: floating marks with specific jobs
Buoys are floating aids portrayed according to their charted type, color, shape, and available topmark. Supported examples include:
- Lateral marks defining the sides of a channel
- Cardinal marks indicating the safest side on which to pass a danger
- Isolated-danger and safe-water marks
- Special-purpose marks associated with cables, pipelines, work areas, or other charted purposes
- Mooring buoys and other recorded buoy types
A lit buoy can also carry a flare and characteristic. Tap it to inspect the available ENC attributes rather than identifying it from color alone.
Lateral-mark meaning depends on the IALA region and direction of buoyage. Do not apply a memorized “red right returning” rule until you have confirmed the local system and direction.
Beacons: fixed aids
Unlike a floating buoy, a beacon is fixed to the seabed, shore, or a structure. SeaVectors preserves its supported chart symbol, color, category, and—when lit—its associated light portrayal and characteristic.
Fixed does not mean infallible. A beacon can be damaged, obscured, altered, or temporarily unlit. Compare charted information with what you actually observe.
A practical harbor-approach workflow
- Before departure, enable Lights, Depth, Hazards, Traffic, and Restricted-area layers.
- Zoom into the approach and identify the principal lights, buoys, and beacons along the intended route.
- Tap each critical aid and note its type, color, characteristic, period, and nominal range.
- Inspect sector boundaries or leading beams and understand what each color or alignment indicates.
- Confirm the local IALA buoyage system and direction.
- At night, use the Night chart style and reduce device brightness appropriately.
- As you approach, compare the expected sequence and rhythm with visual, radar, AIS, depth, and other available observations.
- If an aid is missing, inconsistent, or doubtful, do not force the plan—slow down, reassess, and use an alternative means of navigation.
This preparation turns the display into an identification plan rather than a collection of symbols.
Tips for a clearer display
- Keep the Lights group on for harbor approaches, confined waters, and night navigation.
- Zoom in enough for characteristics and sectors to appear.
- Reduce unrelated labels or layers instead of hiding critical aids.
- Tap before guessing when two nearby marks look similar.
- Return to north-up periodically so sector bearings and the wider approach remain easier to interpret.
Troubleshooting
- No lights, beacons, or buoys appear — enable the Lights group and zoom in.
- A light has no sector arcs — it may be all-around, or the ENC may not contain sector information.
- A narrow sector is difficult to see — zoom in and look for its symbolic beam or select the light.
- A characteristic seems cryptic — separate it into rhythm, group, color, and period, then inspect the info sheet.
- A buoy is not where expected — floating aids can be off station, moved, damaged, or missing; treat their positions appropriately and verify.
- The real light is not visible inside nominal range — visibility is affected by environmental, geographic, equipment, and observer-height conditions.
Experience the difference in familiar waters
Open an approach you already know and compare the charted sectors, characteristics, and buoy types with the real aids. This is one of the quickest ways to appreciate the difference between a generic map and an interactive ENC portrayal.
Install SeaVectors and start the 30-day full-access trial, then continue with Reading the ENC Chart and Map Layers & Detail Control for the broader chart workflow.
Navigation safety
Aids can be unlit, obscured, off station, damaged, changed, or misidentified. Verify critical information against current official charts, notices, and light lists where applicable. Maintain a proper lookout and use all available means—including position, depth, radar, AIS, and visual bearings—to navigate safely.