Francis Searchlights

Lumens measure the total visible light emitted by a source. Candela measures luminous intensity in a particular direction and is therefore important for concentrated searchlight beams. Lux measures illuminance at the target surface: one lux is one lumen per square metre. A searchlight can have fewer lumens than another product and still achieve a longer range if its optics concentrate the light more effectively.

It is the distance at which the manufacturer specifies that the beam still produces approximately 1 lux on the target. It is a useful comparison value only when products are compared at the same lux reference and under comparable test conditions.

Not directly. A 2 lux figure uses a higher required illuminance at the target and is therefore a stricter reference. Always compare searchlights using the same lux basis, and check the beam divergence and test conditions as well.

A narrow beam concentrates the available light into a smaller area and normally gives greater reach. A wider beam illuminates more area but usually at a shorter range. Adjustable or remote focus is useful when the same searchlight must switch between long-range spotting and wider-area illumination.

There is no single best source. LED offers long life, instant start, high efficiency and low maintenance. Laser LED is suited to very long-range work with a highly concentrated beam. Halogen remains simple to service and uses replaceable lamps. Xenon provides very high directional intensity but needs dedicated high-voltage control gear. Metal halide, EmArc and CSI are specialist high-intensity sources used where their particular optical performance is required.

Choose LED for most general marine searchlight duties where efficiency, lifetime, low maintenance and a useful adjustable beam are priorities. Choose Laser LED when very long range is the main requirement and a narrow high-intensity beam is operationally useful. Final selection should also consider control method, installation height, beam spread and the environment in which the light will be used.

Manual units are positioned locally by deck or cabin controls and are often mechanically simple. Remote control models use an electric pan-and-tilt mechanism operated from the bridge, normally with a joystick or control panel. Remote systems can add variable speed, auto-home, remote focus, azimuth indication, master/slave panels or integration with other bridge systems.

Deck control means the operator handles the searchlight locally on deck. Cabin control uses a mechanical arrangement that allows the searchlight to be aimed from a protected position below or behind the mounting surface. Pedestal mounting raises the searchlight above the deck or structure and can provide the required operating height and clearance. The correct arrangement depends on vessel layout, access, visibility and structural support.

Confirm supply voltage and available power, mounting footprint and structural support, cable routes, control panel location, pan-and-tilt clearance, beam obstruction, deck penetration and sealing, ingress protection, ambient temperature, service access and any hazardous-area requirements. Remote installations should also confirm the control architecture and communication cabling.

Twinhead systems increase total light output and can provide broader or redundant illumination. Azimuth indication shows the direction in which the searchlight is pointing, which is useful on bridge-controlled systems. Thermal camera configurations combine active illumination with passive thermal imaging for patrol, surveillance, search and night operations.

SOLAS regulation V/19.2.2.2 requires ships of 150 gross tonnage and upwards and passenger ships irrespective of size to be fitted with a daylight signalling lamp, or other means of communicating by light during day and night, using an electrical energy source not solely dependent on the ship's power supply. Applicability to a specific vessel should always be confirmed against its flag State, statutory regime and class requirements.

IMO Resolution MSC.95(72) sets the performance standard for daylight signalling lamps. Among other requirements, it specifies at least 2 nautical miles daytime visibility at an atmospheric transmission of 0.8, corresponding to 60,000 candela, together with limits for beam divergence and an indication of operational status. Compliance must be assessed against the complete standard, not one figure alone.

Yes. COLREG Rule 36 permits a vessel to direct a searchlight beam toward a danger when necessary to attract attention, provided this is done in a way that does not embarrass another vessel. Attention signals must not be mistaken for signals prescribed elsewhere in COLREG or for an aid to navigation, and high-intensity intermittent or revolving lights such as strobes should be avoided.

No. Approval applies to specific equipment and configurations, not automatically to an entire manufacturer range. Francis identifies the FSP127 Mk5 Aldis signalling lantern as type approved for MED/SOLAS daylight signalling requirements. Other searchlights should be selected according to their intended duty and any vessel-specific approval requirements.

Yes. Suez Canal Authority Rules of Navigation, Article 28, specifies a dedicated projector arrangement including bow mounting on the vessel axis, approximately 1,800 m range at 1 lux under the stated atmospheric transmission factor, at least 3 million candela, split-beam capability, corrosion-resistant construction, minimum IP55 protection and type-test documentation. SCA Circular 1/2026, effective 15 May 2026, requires vessels to provide their own compliant projector. Always check the latest SCA rules and circulars before a transit.

Send the vessel or application, required range if known, preferred light source, manual or remote control, supply voltage, mounting arrangement, quantity and any special requirements such as azimuth indication, thermal camera, low-temperature operation or bridge integration. If you do not know the correct model, MariTeam can select suitable options from the operating requirement.

Send the searchlight model, product number, serial number, required quantity and any Francis part number you already have. A nameplate photo, manual page, exploded drawing, component photo or existing spare-parts list can also be uploaded to the Francis RFQ so MariTeam can identify the correct revision.