Scientific studies of hull design coupled with a need for speedy transport of mail, passengers, and rare products from the Far East led to the clipper ship.  Some clippers were constructed with four, rather than three, masts to increase sail area.  Iron or even steel frames could be planked with wood to make the hull more sturdy. Clippers continued to be useful throughout the century, even in the days of steam.   The Cutty Sark,  built in 1875, was designed for strong winds and once clocked 17 1/2 knots.  

Clipper ships may be constructed in the shipyard. In time of war, clippers are more likely to run a blockade  or escape from hostile fleets than are other merchant ships.