PEL-6 Sector Light Enhancing Safe Naval Entry to Remote Coral Atoll, Indian Ocean
To ensure safe passage through a narrow, invisible underwater channel within a remote coral atoll in the Indian Ocean, a customized PEL-6 sector light solution was developed and deployed. The challenge involved addressing extreme environmental and navigational constraints—including unpredictable currents, drifting buoys, limited access, and the absence of commercial power.
The result is a highly efficient, solar-powered navigation aid capable of providing precise guidance to naval vessels approaching the reef.
Background and challenge
The installation site presented a wide range of technical challenges:
- The dredged access channel was only 228 meters wide and completely invisible from the surface.
- Vessels transiting daily included naval ships up to 41 meters in beam, requiring pinpoint accuracy when entering the anchorage.
- Ocean currents often struck the vessels side-on near the entrance, making navigation hazardous.
- Due to a steep drop-off just outside the reef and the unreliability of entrance buoys, traditional aids to navigation were ineffective.
- The only feasible site for an aid was 7.3 nautical miles beyond the reef entrance.
- Any light had to be visible at 10 nautical miles during daylight hours.
- The remote site lacked commercial power and had limited accessibility by both land and sea.
Given these challenges, a direction-indicating sector light system was considered the only effective solution.
Solution – PEL-6 Sector Light with Custom Projection Optic
The project began by using the existing PEL-6 sector light as a foundation. To meet the new performance requirements, a highly customized system was designed and built:
New 600 mm Diameter Projection Optic
A major enhancement was the development of a new optical system using a 600 mm diameter projection lens.
This enabled the beam width to be reduced from 3.5° to just 1.6°, increasing the light intensity by 4.8 times to 3,500,000 candela in the white sector.
A double-folded optical system using two Mangin mirrors was implemented to keep the projector compact.
Lightweight Stainless Steel Tower
To maintain sector alignment at long range, the tower needed extreme torsional stiffness, with a deflection tolerance of less than 0.01° at the top.
It was constructed from marine-grade Avesta stainless steel to ensure structural integrity and long life in the harsh marine environment.
The design eliminated the need for painting, maintenance, or security fencing, as site access is inherently restricted.
Solar Power Supply with Demand-Based Control
Commercial power was not available, so the system was powered entirely by solar energy. To maximize efficiency, a radio-controlled switch with a 2-hour timeout was used to activate the light only during necessary transits—typically just once per day.
The entire power system was installed on the upper platform to minimize voltage losses and reduce vulnerability to lightning from long cable runs.
Integrated Remote Monitoring and Control
Given the radio link already in place, a full remote monitoring system was integrated at minimal additional cost.
This setup provides continuous data on battery status and lamp usage, with an emergency override switch mounted on the tower in case of radio failure.
Outcome – Reliable and Precise Navigation Aid in an Extreme Location
The deployment of the PEL-6 sector light, enhanced with a customized projection system and solar-powered infrastructure, has delivered a highly accurate, low-maintenance, and energy-efficient solution. The central white sector is only 0.2° wide—equal to 47 meters at the channel entrance—providing precise directional guidance for vessels in challenging ocean conditions.
This solution has redefined what is possible for navigation aids in extreme remote environments, combining high performance with long-term reliability and minimal servicing.
Featured Marine Product
PEL-6
