Screw-pile lighthouse

The first screw-pile lighthouse to begin construction was built by the blind Irish engineer Alexander Mitchell.

[1] In the United States, several screw-pile lighthouses were constructed in the Chesapeake Bay due to its estuarial soft bottom.

Non-screwpile (straightpile) tubular skeletal tower lighthouses were built, usually of cast-iron but also of wrought-iron piles, both onshore and offshore, typically on soft bottoms such as mud, sand, and swamp.

To protect the structure from ice floes an ice-breaker consisting of a pier of 30 iron screwpiles 23 feet long and five inches in diameter was screwed down into the bottom and interconnected at their heads above the water reinforcing them together.

In areas such as the Florida Keys, where the bottom is soft coral rock, diskpile foundation lighthouses were built.

In coral reef areas where sand is also prevalent, a cast-steel screw was fitted to the end of the pile to give it more anchoring ability.

The tall offshore skeletal tower type was built in exposed open water at major coastal sites where visibility over ten miles was required.