Electronic visual distress signals use high-output electric light rather than a pyrotechnic flame to help make a vessel or casualty easier to locate. They are increasingly discussed as part of modern marine safety equipment, but their legal status and intended role need to be understood clearly.
EVDS stands for Electronic Visual Distress Signal. In simple terms, it is a light-emitting device intended to make a person or vessel in difficulty more visible. Unlike a conventional pyrotechnic hand flare, an EVDS does not rely on a burning chemical composition. It uses electrical power and LEDs to produce a visible light signal.
That difference affects how the equipment is stored, tested and used. A rechargeable electronic signal can be functionally checked before departure, while a pyrotechnic flare is normally a single-use item that cannot be test-fired and then returned to service.
An electronic visual signal is particularly useful for location. Once the alarm has been raised by VHF DSC, an EPIRB, a phone call where coverage exists or another recognised distress-alerting method, rescuers still have to identify the casualty visually. A strong, distinctive light can help with that final stage of the rescue.
The Royal Yachting Association describes EVDS as potentially useful locating devices, particularly in the final mile of a rescue. It also stresses that they are not currently listed as an internationally recognised distress alert under COLREG Annex IV. You can read the RYA guidance on electronic visual distress signals.
Not automatically. This is an important distinction. The Maritime and Coastguard Agency states that where a vessel is required to carry approved pyrotechnic flares, an EVDS cannot simply be substituted for that mandatory equipment. On vessels where flare carriage is not mandatory, owners still need to understand that an EVDS is not currently an internationally recognised distress signal in the same way as the signals listed in COLREG Annex IV.
The current MCA position is set out in Marine Information Note 542 Amendment 3. Regulations can change, so vessel operators should always check the latest requirements for their vessel and area of operation.
Brightness alone is not the whole story. Beam angle, flash pattern, colour, operating duration, battery condition, construction and visibility against background lighting all affect practical performance. A very narrow beam can produce high intensity in one direction but requires accurate aiming. A wider controlled beam gives greater angular coverage but spreads the available light over a larger area.
UltraFlare Daylight uses a directional three-LED optical system designed around strong visible output and controlled beam geometry. The full-size UltraFlare Daylight has independently measured peak luminous intensity exceeding 40,000 candela, with a 45 degree horizontal and 15 degree vertical display.
The most sensible approach is layered. Distress alerting tells the rescue services that you need help and ideally provides your position. Visual signalling then helps rescuers identify you as they approach. No single piece of equipment should be expected to cover every stage of an emergency.
For more detail, see our UltraFlare technology page or read our guide to distress alerting and visual location.
Last reviewed: October 2026. This article is general information and does not replace current MCA, RYA or vessel-specific regulatory guidance.
See the independent testing, optical design and current UltraFlare product range.