A screw like this one was at the bottom of each of the seven pilings (legs) of this lighthouse—allowing the leg to be screwed down into the soft Bay bottom. It would have been much easier to simply drive the leg straight down into the mud, but screwing it in diagonally gave the lighthouse a more staple foundation.The screws also helped keep the lighthouse secure in the winter, when ice froze around the pilings. When the tide rose beneath the ice, it tried to lift the pilings with it, but the screws were designed to hold them fast.
Screwpile lighthouses were a great innovation—they could be built out in the middle of the Bay, and could be seen by boats far from the shore. But winter ice remained their greatest enemy. Even beneath a frozen Bay, the tides rise and fall, lifting and lowering the ice above them. Over a long winter this continuous action can place enormous pressures on a lighthouse’s slender legs. In all thirteen screwpile lighthouses were destroyed by ice and nearly every screwpile lighthouse suffered damage. Only four remain today. Of those, only one is in its original location, the other three—including this one—have been moved to land to preserve them.
(Waterways & Vessels) Includes location, directions, 4 photos, GPS coordinates, map.
