SS Prindoc (1901)

The gunship USS Michigan became the first iron-hulled vessel built on the Great Lakes, upon her launching in 1843, in Erie, Pennsylvania.^[1] By the mid-1840s, Canadian merchants were importing iron vessels prefabricated in the United Kingdom.^[2] The first iron–hulled merchant vessel built on the lakes, Merchant, was built in 1862, in Buffalo, New York.^[3] Despite Merchant's clear success proving the potential of iron hulls, ships built from wood remained preferable until the 1880s, due to their lower cost, as well as the abundance of high quality timber and workers trained in carpentry.^[4] Between the early–1870s and the mid-1880s, shipyards around the Great Lakes began to construct iron ships on a relatively large scale.^[5] The most notable being the freighter Onoko, built by the Globe Iron Works Company, which became the largest vessel on the lakes upon her launch in 1882.^[6] In 1884, the first steel freighters were built on the Great Lakes.^[7] By the 1890s, metal had become a common hull material used on the lakes.^[8] The development of the pneumatic rivet gun and the advancement of gantry cranes enabled shipyard employees to work at an increased speed, with greater efficiency.^[9] This, combined with the rapidly decreasing steel prices, contributed to the rapid increase in the size of lake freighters in the late 19th and early 20th centuries.^[10] The first 400-foot (121.9 m) freighter was built in 1895, the first 500-foot (152.4 m) freighter arrived on the scene five years later.^[11]

Throughout the 1880s, the iron ore trade on the Great Lakes grew significantly, primarily due to the increasing size of the lake freighters, and the rise in the number of trips they made to the ore docks of Lake Superior.^[12] As the railways were unable to keep up with the rapid production of iron ore, bulk freighters became integral to the region's iron ore industry.^[12] By 1890, 56.95% of the 16,036,043 long tons (16,293,372 t) of the iron ore produced by mines in the United States was sourced from the region surrounding Lake Superior.^[12] Freighters engaged in the iron ore trade frequently carried coal on upbound voyages to fuel mining equipment and infrastructure, while hauling ore when downbound.^[13]

The wreck of Prindoc has never been found. As of 2025, she is the third largest undiscovered shipwreck, both on Lake Superior and on the Great Lakes, behind the 468-foot (142.6 m) freighter D. M. Clemson, and the 436 feet (132.9 m) freighter James Gayley.^[14]