|Seeing The Light
While LED's have been around since the late
1960's, and have been ubiquitously incorporated into displays on alarm
clocks, microwaves and calculators for many years, until relatively
recently the technology only allowed the production of relatively low
brilliance units, and in any color - as long as it was red. As solid state
devices based on semi conductor technology, LED's produce a minimum amount
of heat energy in the process of creating light, and are incredibly energy
efficient to boot. Improvements in LED technology over the past decade
have resulted in the creation of significantly higher light output levels,
along with the production of units LED's which natively output white,
blue, green and yellow light in addition to the standard red. As a result,
LED's are now becoming commonplace in automotive tail light and traffic
signal applications, where they are able to replicate the standard red,
amber and green sequence of intersection control without the addition of
colored lenses which serve to reduce inherent intensity.
While virtually all of the maritime illumination manufacturers now offer LED lighting systems, the Coast Guard appears to have narrowed its focus on two major manufacturers of LED lights, conducting extensive field testing of units produced by Vega Industries and Carmanah Technologies. While Carmanah LED units have been installed on buoys in a number of locations around the Ninth District, the Vega VLB-36 LED unit installed in the rear range tower at Grand Haven in 2000 has the distinction of being the only LED unit currently installed in a major fixed aid to navigation on the Great Lakes.
As witness to today's global economic environment, Vega Industries is located in Porirua, New Zealand, approximately ten miles north of the capital city of Wellington. The company was established in 1972, originally offering a line of PEL sector lights to enable single light range indication at harbor entries. The company soon branched out into the manufacture of other maritime illumination systems, and gained international prominence in 1993 when it shipped its first consignment of VRB-25 rotating beacons to the US Coast Guard. Since that date, over 200 VRB-25's have been installed in fixed aids throughout the country, with a few notable examples to be found on the Great Lakes at Harbor Beach, Outer Island and Oswego West Pierhead.
Vega currently offers two LED lighting systems, the VLB-44 and VLB-48, which have largely superceded the VRB-36 installed at Grand Haven. All of these light assemblies are virtually identical in outward appearance, with their bases and main housings machined from marine grade aluminum. The LED array, which can be ordered in white, red, green, blue or yellow, is oriented horizontally around the circumference of the light module. A precision molded acrylic lens surrounds the LED's to focus their light into a coherent horizontal band, affording a tight vertical divergence to ensure that the maximum amount of light is directed directly in a horizontal plane, and not wasted on the ground or the sky.
The VLB-44 features a vertical divergence of 10º, a peak intensity of 1,535 candelas, and a maximum effective range of 6 nautical miles, and is designed primarily for use on buoys and minor aids. The VRB-48 features a narrower vertical divergence of 5º, a peak intensity of 2,756 candelas, and a maximum effective visible range of 15 nautical miles, making it suitable for installation in larger fixed aids. These lights also feature a modular design, which allows up to eight LED modules to be stacked vertically, significantly increasing the overall intensity and visible range.
By virtue of an integrated programmable controller, the lights can also be readily programmed to exhibit a virtually unlimited range of flash characteristics. Program changes are entered into a small hand-held controller which contains over 200 built-in characteristics and memory space to hold 25 additional custom programs. Once the desired characteristic has been selected, the program can be beamed directly to the light by way of two-way infra red ports in both the light and controller. This to-way infra red communication also allows voltage, light intensity, wattage and other metrics to checked remotely with the controller without having to open the light to attach test leads or diagnostic equipment directly to the light itself. As a result, the modules are factory sealed to provide a reliable 10-year maintenance-free effective life. Equipped with four plastic "bird spikes" on top of the uppermost LED module in the stack, feathered interlopers are discouraged from making a safe landing, further eliminating the need for frequent cleaning of the acrylic lenses.
As witness to the reliability and service free life cycle of these new LED light systems, the VLB-36 installed in the lantern of the Grand Haven rear range tower three years ago has thus far required no service, and has performed flawlessly on a daily basis since its installation by the ATON team from USCG Station Muskegon. According to mariners the light is readily visible from far across the water, and serves its purpose extremely well.
Information courtesy of the Vega Industries catalog