Medium clipper

A Medium clipper is a type of clipper designed for both cargo carrying capacity and speed. An evolutionary adaptation of the extreme clipper, the medium clipper had been invented by 1851, when the hull type appeared in U.S. shipyards. Medium clippers continued to be built until 1869, when the Glory of the Seas, one of the last known medium clipper ships to be built, was launched by the firm of Donald McKay & Co.

The 1850s saw two major gold rushes in the English-speaking world - in Australia and Nevada - as well as continued development of placer gold mining in the Sierra Nevada mountains of California.

As these precious metal mining activities matured, the working populations of the affected gold and silver mining belts began to demand large quantities of manufactured goods. Shippers began to look for a ship design that would speed large quantities of boxed, barrelled, or crated cargo to Melbourne or San Francisco.

At the beginning of the 1850s, the dominant U.S. fast sailing ship design was the extreme clipper, properly defined as a cargo vessel with a 40-inch-or-more dead rise at half floor. This refers to a sail-powered cargo hull with a relatively flat-floored rear half, tapering as one moves forward along the hull to a relatively sharp forward half.

Extreme clippers successfully served the 49ers who reached California placer fields during the opening years of the rush, but negative aspects of the design soon became apparent. The sharp-floored forward halves could not carry as much cargo as a full flat hull. In addition, the sharp-floored forward halves lacked the buoyancy of the rounded rear halves, and this asymmetrical buoyancy tended to strain and weaken the hull. The working lifespan of an extreme clipper ship tended to be short.

By 1852 U.S. shipbuilders such as Donald McKay had begun to develop a new type of clipper ship hull, which combined a flat-floored hull for maximal cargo capacity with a clipper bow resembling that of the extreme clipper ship. The stern, masts, spars, and sail area also resembled the extreme clipper ship. The half floor dead rise of the true extreme clipper ship was, however, no longer to be seen.

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