Screwpiles: The Forgotten Lighthouses

Screw Cylinders Replace Smaller Pilings The adjacent plan is for the foundation specifications at White Shoal and Point of Shoals, 1870. This foundation replaced the original five-inch-diameter solid screw pilings with 16-inch-diameter screw cylinders. The screw diameter increased from two feet to three feet, resulting in much greater holding power. The leading edge of the cylinder was sharpened to ease the insertion into the bottom. The photograph shows the screw cylinders used for the Roanoke Marshes Lighthouses with the larger diameter cylinder and screw. You can also see how the leading edge of the cylinder was sharpened. The change in specifications worked. As of the date of this book’s publication, the foundations at White Shoal, Point of Shoals, and Deep Water Shoals all remain in place.

Screw cylinder on display in Manteo, North Carolina

White Shoal foundation details National Archives RG 26

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