Visual Buoyage and Luminous Range Overview

Visual Buoyage Guide

• Region B, by night, uses a preferred and secondary channel.
• Region B, by day, uses a preferred and secondary channel.
• Buoyage illustrations show the preferred and secondary channels marked with buoys and arrows.
• Numerical markings on buoys indicate channel direction and type.

Luminous Range Explained

• Luminous range is the maximum distance a light can be seen.
• Nominal range is the maximum distance a light is visible in clear weather (10 nautical miles).
• This applies to most lighted navigation aids, but exceptions exist (range lights, directional lights, and private aids to navigation).
• Current weather visibility affects luminous range.
• In clear weather, visibility is greater than nominal range.
• In poor weather, visibility is less than the nominal range.
• The luminous range is the realistic, adjusted range considering the weather.

Luminous Range Diagram

• Nominal Range: The ideal range of a light in clear weather (10 nautical miles).
• Real-world Visibility: Weather visibility impacts the observed range. Visibility less than the nominal range will reduce the distance a light can be seen. Higher visibilities will allow observers to see lights further.
• Luminous Range: The current distance a light can be seen based on weather conditions, adjusting the nominal range.
• Diagram/Chart: Used to determine the luminous range based on the nominal range of the light and current weather visibilities.

Geographic Range of Visibility

• Geographic range is the furthest distance an object can be seen based on the height of the object and the observer's eye level, taking into account Earth's curvature.
• A table is provided that shows the distance (in nautical miles) related to height (in feet/meters).
• To find the geographic range: Use the table to find the distance for the object's height and add it to your eye height from the table to calculate the total.

Types of Navigation Signals

• Lighted aids in navigation operate automatically at night, turning off during the day.
• Lateral lights (red and green): Indicate the port or starboard sides of channels or obstructions.
• Non-lateral lights (white and yellow) have purposes determined by their shapes/colors, letters, or rhythms.
• Light sectors: Warn of dangers, shoals, obstructions, nearby land.
• Lighted markers have special attributes: preferred channel marks, safe water marks, isolated danger marks.
• Lighted markers and rhythms include flashing, flashing (2) or Morse code "A". (short and long flash).
• Retroreflective materials enhance night visibility, matching marker colours.

Light Characteristics

• Fixed lights are continuous and steady.
• Occulting lights: have a period of darkness (eclipses) typically equal in length to the periods of light.
• Isophase lights: light and dark are equal in duration during a period.
• Flashing lights: the light duration is less than the dark for a period.
• Special characteristics include quick, long, group, composite, group flashing, and quick flashing lights.

Abbreviations for Navigation Aids, Lights, and Signals

• Provides abbreviations for light characteristics, sound signal characteristics, and aids to navigation.

Simplified Definitions

• Luminous range: the maximum distance a light can be seen, depending on conditions and the observer's eyesight.
• Nominal range: the typical distance a light is visible in clear weather.
• Geographic range: the farthest that a light can be seen due to the curvature of the earth and the height of the observer and the light's position.
• Visibility of a light: the typical distance in nautical miles a light can usually be seen in clear weather.
• Range lights: Two or more lights in a line that give a visible range.

Fog Signals and Systems

• Fog signal types are detailed, including bells, diaphones, explosives, gongs, horns (Klaxon, membrane, reed), sirens, underwater acoustic signals, and whistles.

Characteristics of Lights

• Contains descriptions of light types, with examples and abbreviations. (fixed, occulting, isophase, flashing, long flashing)

Visibility Table

• Provides a table to determine distances (nautical miles) objects can be seen at sea considering elevation of the object and the height of the observer.

Luminous Range Diagram

• A diagram shows the relationship between light intensity and distance visibility, accounting for different ranges of nominal visibility.