Knowledge base

An Electronic Visual Distress Signal (EVDS) is a portable light used to attract attention and help rescuers locate a vessel or person in distress. It uses high-efficiency LEDs and defined flash patterns to provide a clear, recognisable signal in low visibility conditions.

What an EVDS Does

An EVDS provides bright, consistent light that signals distress to others nearby. It is designed for quick activation, long runtime, and dependable operation in challenging environments. The light pattern, usually an SOS sequence, communicates a universal distress message.

How It Works

Each EVDS contains a powerful LED light source, optics that shape the light for full visibility, a sealed housing, and a power supply, typically user-replaceable batteries. Together, these components deliver reliable performance and simple operation, even in poor conditions.

Why Standards Matter

EVDS performance is regulated by an industry standard known as RTCM 13200.0. Created by the Radio Technical Commission for Maritime Services, this standard defines how bright an EVDS must be, what colour it should display, how long it should run, and how durable it must be.
Devices that meet these requirements can demonstrate predictable, verifiable performance.

In the United States, EVDS products that meet these standards may be recognised as equivalent to an electric distress light under 46 CFR 161.013, subject to national approval. Users should always confirm local carriage rules before relying on any device in place of another.

When to Use an EVDS

An EVDS is valuable in many marine and operational situations:

• Night navigation or emergencies when visual detection is vital.

• Extended search periods where long runtime helps maintain visibility.

• Workboat and training operations needing consistent, testable performance.

• Environments that benefit from simple battery replacement and low maintenance.

How to Use It Effectively

• Keep the light visible and unobstructed.

• Activate the SOS mode for maximum recognition.

• Replace batteries with the recommended type.

• Test the device regularly to confirm readiness.

• Store it in a dry, easily accessible location.

Choosing the Right EVDS

Look for a device tested to RTCM 13200.0, with clear documentation, durable construction, verified runtime, and straightforward operation. For detailed specifications and accessories, see the HALO Pro EVDS page.

For maintenance and use guidance, visit Support.