Patently a Great Man – Abe Lincoln’s Boat Flotation Device

May 22, 1849

Abraham Lincoln, at the time 40 years old and a self-described “prairie lawyer” from Illinois (as well as a recently retired one-term U.S. congressman), was issued a patent for a flotation device for the movement of boats in shallow water. To date, this patent is the only one ever registered to somebody who served as U.S. president.

Patent No. 6,469 was specifically classified as “A Device for Buoying Vessels Over Shoals.” Lincoln’s proposed device was made up of large bellows attached to the side of a boat just below the water line. The idea was that, once the boat reached a shallow place in the water, the bellows would be filled with air to raise that boat higher so that it could avoid shoals and other obstacles. Lincoln’s motivation for coming up with such an invention resulted from two personal experiences out on the water.

The first of these experiences happened when Lincoln was about 22 and among those traveling on a flatboat to help take goods from New Salem, Illinois, to New Orleans via the Sangamon, Illinois, and Mississippi Rivers. Before Lincoln and his fellow laborers left the Sangamon River for the Illinois River, however, their flatboat got stuck on a dam. The vessel started to fill with water and was in danger of sinking, so Lincoln took it upon himself to unload some of the cargo and then drill a hole in the bow. Once the water had drained out of the flatboat, Lincoln plugged the hole and – with help from his fellow laborers and some local residents – managed to finally set that flatboat free and get it over the dam in order to continue the journey to New Orleans.

The second experience took place just a couple of years later while Lincoln was traveling across the Great Lakes on a boat. The boat ran onto a sandbar, and it was only after a great deal of manual effort that the vessel was ultimately swung clear and dislodged.

Both of the aforementioned incidents inspired Lincoln to think about ways to lift boats so that they could avoid obstructions in the water, and the end result was his proposed flotation device. Lincoln’s patent was issued just over two months after he filed it.

Lincoln’s invention was never commercialized and put to practical use. Above all else, however, the patent reflected Lincoln’s lifelong connections and fascination with transportation. As a lawyer in his pre-presidential years, the man who would be famously nicknamed “The Rail Splitter” handled numerous transportation cases stemming from the nation’s steady westward expansion and involving such matters as railroads, bridges, and river barges. As president during the Civil War, Lincoln was strongly interested in the development of such innovations in mobility as ironclad ships and observation balloons. He also signed into law the Pacific Railway Acts of 1862 and 1864 that helped bring about the First Transcontinental Railroad, which was completed just a few years after his death.

For more information on Abraham Lincoln’s 1849 patent for “A Device for Buoying Vessels Over Shoals,” please check out and

3 thoughts on “Patently a Great Man – Abe Lincoln’s Boat Flotation Device

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