By BMC Dennis Dever, USCG ANT Miami, 1999
There was a problem with the standard terrestrial range system at Port Everglades / Ft. Lauderdale, Florida. Gaining size over the years, the superstructures of moored ships obstructed the 85-foot forward tower. The 135-foot rear range tower remained obvious, but the old FA 240 lanterns provided poor daylight availability and were in a losing nighttime battle with proliferate city lighting. Moreover, the 6KRW range boards were difficult to see and align from the channel entrance, especially with the late afternoon sun behind them.
Rather than increasing the height of both towers, the dayboard size, and installing two brighter lanterns, we campaigned to install a single Vega PEL sector range light on the rear tower and eventually discontinue the forward optic and both sets of range boards. The PEL is best suited for places where only one tower is practical, and is the first of its kind in the Seventh Coast Guard District.
This particular model, a PEL-3-3.5D, has five sectors ranging between 15 minutes to one degree of arc. It is about six feet long, weighs 120 pounds, and costs $22,000. Conspicuous day or night, the instrument shows a fixed white light in mid-channel. When inbound, moving out of the center toward starboard, the light becomes alternating red/ white...the further from mid-channel, the longer the red flash. Once in the channel’s starboard side, the light shows fixed red. Going to port shows white / green, then fixed green. The total horizontal divergence is 3.0 degrees, and no light is visible at the marked channel’s edge, just inside the gated buoys and lateral lights. Describing the PEL in the Light List must be a unique challenge.
We at ANT Miami saw this project as a great opportunity to try out some relatively new technology – one that could make us heroes to a major port at the risk of unparalleled embarrassment if we fell short of what we promised. At first, this optic was cloaked in mystery, as only a couple of partners in this project knew what it was and the theory behind its operation. Coming from New Zealand, it was contracted, custom built, and delivered totally by fax and email...no traditional voice to voice communication. Fortunately, Martyn Cook, General Manager of Vega Industries, stopped by Miami Beach while in the U.S., and aligned United States Coast Guard CEU, OAN, Group and ANT stakeholders with a very enlightening presentation. Now we understood the inverse square law and photocell hysteresis.
Lt. Scott Wagner of CEU Miami joined us for precise measurements of the light and tower platform, and then designed an infinitely adjustable mounting plate. This proved very important later on. Specialty Towers Corporation modified the tower, brought in a crane, and assisted with the light’s placement. We delivered electrical power via commercial 120 VAC to the platform, fed into a standard CG 12 VDC high wattage power supply, thence to a Delco 100 amp battery, to the light itself. The battery was Vega’s recommendation, since it stabilizes any surges from the power supply. We could also disconnect commercial power for short periods without extinguishing the light. Incidentally, 100-watt H-5 halogen lamps illuminate the optic in a miniature 6P lampchanger. These are finally positioned, while energized, using a collet tool. Wearing of welding goggles is highly recommended. A computer aided lamp controller (CALC)-2000 and logic inverter monitor the electronic functions; adjustable night intensity reduction is one example.
Fine directional alignment, both horizontal and vertical, was a tedious process due to the precise sector boundary resolution (about one minute of arc – the minimum angle at which the human eye can separate two lights from the illusion of one). From the flying bridge of a large AUXFAC cabin cruiser, we surveyed the light from seaward, compared sector positions to the old dayboard alignment, and gave direction to the tower. Once centered, we swept the channel from all angles and found the light operating exactly as specified. Whew.
Local pilots report that the new light is a substantial improvement, it is highly visible day and night, and the sector color changes shows more precise relationship to center channel instead of judging the distance between two dim lights (assuming both lights were visible). Now we’ll service one light instead of two, focusing is much easier, it requires two visits yearly, and the light should remain in place for about 20 years. Also, no more struggling with big dayboards 135 feet above the ground. The PEL’s drawback is components are expensive, but should rarely, if ever, need replacement. We plan to leave the existing forward range light in operation for about 60 days, giving waterway users a good adjustment period. The dayboards will come down when the inevitable peeling commences.
Photo courtesy of Dennis Dever
Photo courtesy of Dennis Dever