Sailing at night on a sailboat can offer a wonderful view of the starry sky, a feeling of silence and peace, but also the challenge of night navigation. However, it is important to be prepared and take the necessary precautions to ensure a safe and enjoyable experience.
Lighthouse - Your Reliable Helper in the Dark
A lighthouse is a tower structure designed to emit light from a system of lamps and lenses, serving as a navigational aid at sea or on inland waterways.
Lighthouses mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe harbor entrances. They also assist in aerial navigation, making them multifunctional safety devices.
How to Read Lighthouse Marks on Charts
Name: The lighthouse name (e.g., "Porer Lighthouse")
Fl(3): Abbreviation of the light type (e.g., Fl = flashing)
WGR: Light color - "W" for white, "G" for green, "R" for red
15s: Cycle period (e.g., 15 seconds from start to repeat)
21m: Height of light above sea level (e.g., 21 meters)
15-11M: Range in nautical miles (15M for white light, 11M for green/red)
Types of Lighthouse Light Patterns
Fixed Light (F.)
A fixed light, abbreviated "F", is a continuous and steady light. It's used to mark permanent navigational points.
Flashing Light (Fl.)
A flashing light is a rhythmic light in which the total duration of light in each period is clearly shorter than the total duration of darkness. The flashes of light are all of equal duration.
Most commonly used for single-flashing lights that exhibit only single flashes repeated at regular intervals - abbreviated simply as "Fl".
It can also be used with a group of flashes regularly repeated, abbreviated as "Fl(2)" or "Gr Fl(2)" for a group of two flashes.
Occulting Light (Oc.)
An occulting light is a rhythmic light in which the duration of light in each period is longer than the total duration of darkness. In other words, it's the opposite of a flashing light.
It has the appearance of flashing off, rather than flashing on. Like a flashing light, it can be used for single occulting (Oc), groups (Oc(3)), or composite groups (Oc(2+1)).
The term "occulting" is used because originally the effect was obtained by a mechanism (e.g., vertical or rotating shutter) periodically shading the light from view.
Isophase Light (Iso.)
An isophase light, abbreviated "Iso", is a light which has dark and light periods of equal length. The prefix derives from the Greek iso- meaning "same".
Alternating Light (Al.)
An alternating light, abbreviated "Al", is a light which shows alternating colors. For example, "Al WG" shows white and green lights alternately.
Flash Frequency:
Q: Quick (50-79 flashes/min)
VQ: Very Quick (80-159 flashes/min)
UQ: Ultra Quick (more than 160 flashes/min)
Light Colors:
R: Red
G: Green
W: White
Y: Yellow
Practical Tips for Night Sailing
- Pre-voyage preparation: Study the lighthouses in your area using charts and sailing directions
- Adaptation time: Your eyes need 20-30 minutes for complete dark adaptation
- Red light: Use red lights in the cabin to preserve night vision
- Identification: Count flashes and time intervals with a stopwatch
- Backup: Always carry spare light sources and batteries
- VHF Channel 16: Always monitor during night passages
MarinaTips Team
michal
