A beautiful, sunny morning on Tiscornia Beach. The sun illuminates the two lighthouses that comprise the St. Joseph range lights.
Range lights - also known as leading lights- help ships find the harbor entrance from a distance, especially at night. In this case, the two lighthouses are set in line, a few hundred feet apart on a single pier. The inner lighthouse is taller, so it can be seen over the outer lighthouse. As ships approach the harbor, they steer so the two range lights are vertically in line, the inner light directly above the outer light. Keeping these lights in vertical alignment, the helmsman is able to head directly toward them, and into the harbor in times of low visibility.
Range lights also assist ships in determining their position, even if they're not heading to port. Finding a bow or beam bearing may prove difficult using only one distant light or object, since the ship needs to be at an exact angle to take a sucessful bearing. By lining up the two range lights, the navigator knows the ship is in line with the marker, and the bearing is accurate.
Even in these days of modern navigation systems, it's reassuring to see these sister lighthouses on the horizon, guiding ships to safe harbor.
Posted by Tom Gill at Wednesday, November 05, 2014