Lanby buoy

Lanby buoy is a contraction of Large Automatic Navigation BuoY.[1] Lanby buoys were first made in the USA by General Dynamics and adapted by Hawker Siddeley Dynamics for use in British waters in the early 1970s.[2] The buoys were intended to replace lightships and were constructed as a circular hull with a central light to provide all-round visibility and a foghorn. They may also contain radio and radio beacons. The navigation buoy was to be monitored remotely from onshore and was designed to run for extended periods without repair. The running costs were estimated to be as little as 10% of those of a lightship.[2] They are now obsolete.[3]

Lanby buoy (on left) that replaced Lightship Columbia at the Columbia River Maritime Museum in Oregon

Equipment

The original UK models followed the General Dynamics design: power was supplied by three diesel alternators of 230 V, individually rated at 5 kW continuous output. These were each run in a 72-hour operational cycle of 24 hours under power, followed by 48 at rest. Maintenance and refuelling was at six-monthly intervals. A static rectifier provided continuous power at 28 V DC, charging a nickel-iron accumulator to operate the xenon discharge tube main light and the ancillary equipment, including a UHF telemetry link to a monitoring shore station. The Hawker Siddeley models incorporated components from the original General Dynamics design but only two diesel generator sets, one running continuously for six months and one on standby, were found to be sufficient. Revolving sealed-beam main lights were substituted for the discharge tubes because the rotating beams were more easily seen than the original short-duration flashes.[2][4]

Withdrawal

Experience showed that it was difficult to attain the required reliability in British waters due to the high acceleration forces experienced in rough seas with 14m waves and 7 knot currents. Alternative experiments were made with more stable platforms, such as the Royal Sovereign Lighthouse—a concrete tower on a flat base constructed on shore, floated into place and sunk to rest on the seabed.

The automatic technology was later used successfully in more conventional lightships, such as the Calshot Spit lightvessel.[2]

A Lanby buoy replaced the Bar Lightship PLANET in the Mersey estuary in 1972 and remained in service for 21 years before itself being replaced.[5]

References
  1. "Abbreviations". Commissioners of Irish Lights. Archived from the original on 2007-11-19. Retrieved 2008-06-25.
  2. Rowlands, David (1974). "Points of Reference". Design Journal. 310: 48–53. Retrieved 14 August 2020.CS1 maint: ref=harv (link)
  3. Kemp, Peter, ed. (2005). "Lanby buoy". The Oxford companion to ships and the sea (2nd ed.). Oxford, U.K.: Oxford University Press. ISBN 9780199205684.
  4. Beadle, D. G.; Williams, W.F. "The Lanby buoy telemetric system". BBC R&D. BBC. Retrieved 15 August 2020.
  5. "History of the Mersey Lightvessels". Mersey Lightvessel Preservation Society. Archived from the original on 2008-04-22. Retrieved 2008-06-25.


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