Navigation by Lighthouses: Piloting at night.

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Postby island » Wed Apr 04, 2012 6:15 am

US Navy training film demonstrating coastal navigation (piloting) at night using lighthouses and light buoys as points of reference. The light cruiser USS Savannah is piloted in darkness into Chesapeake Bay. Shows how to use the charts and calculate position by taking bearings on the various lights.
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Postby CHUCKX53 » Wed Apr 25, 2012 9:23 am

That's fascinating. Being mostly a 'landlubber' all my life, I see now that it takes continuous attention to be able to navigate a ship by night.
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Postby island » Fri Apr 27, 2012 8:29 pm

The same continuous attention was required during daylight but it was easier because landmarks in addition to lighthouses were visible.

This link is part 1 of the night navigation demonstration video posted above.

In this video note the flash pattern of Cape Charles light is 4-5, 4 flashes then 5 flashes. This light was one of only two Mahan system lenses ever installed. The other was Minots Ledge with a 1-4-3 flash pattern.

The Mahan system was a method proposed in 1892 to display a unique numeric flash pattern for each primary and secondary seacoast (offshore) light thus for having its own unique number a light would be quickly identified without question. This system was not adopted because of the expense to modify the few existing revolving lenses and to replace the many fixed lenses with revolving lenses for over one hundred lights.

USS Savannah (CL-42)---light cruiser, commissioned: 10 March 1938
Displacement: 9,475 tons Length: 608 ft, Beam: 69 ft, Draft: 19 ft 2 in, Speed: 32 kn (37 mph) Complement: 868 officers and enlisted

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