Reverting back to the question of tonnage under the Old .Measure, although some owners took dangerous advantage of its loopholes, reputable owners such as the East India Company took advantage only to the extent of producing good heavy cargo carriers with little pretension to speed, but which were considered safe.

   One restraining factor in British design of merchant ships for the period covering the latter part of the 18th and the early 19th centuries resulted from the almost continuous state of war, which necessitated ships travelling in convoys whose speed was regulated by the slowest vessel. The convoys, which could take a couple of months in assembling, were made compulsory by an Act of 1798, although there were special exemptions if a ship was considered fast enough and sufficiently well armed.
 
   American and other Northern European ships by contrast sailed singly, and consequently studied new forms and gained more practical knowledge. An American ship was estimated to make a passage in about twothirds of the time of a British ship, although it sacrificed capacity in order to do so. The continental European builders applied more scientific knowledge to their ships, since their men of science, especially in France and Sweden, applied themselves to the theoretical knowledge of naval architecture. British theory was sadly lacking in the first thirty years or so of the 19th century, an attempt at forming a school ofstudy having failed owing to opposition from the old school of naval constructors, although the practical aspect of ship construction advanced and workmanship itself was of the highest class in the best shipyards and dockyards.

   The need for speed did exist, however, in other uses of ships, and finelined fast vessels had been operating for some centuries before, notably the privateers, smugglers, dispatch vessels, naval cutters and coastal packets. Smaller craft such as skiffs, wherries, fishing smacks and yachts had fine lines chiefly as a result of a natural form arising from their mode of construction with light planking. Hollow lines were also known from ages back, but there was an unwritten law that hollow lines must be filled in for the larger ocean-going ships, aided no doubt by the desire for as much cargo capacity as possible. The development of the steam vessel in the early part of the 19th century cannot be overlooked in considering the advent of the clipper type. A good example of early steamship lines can still be seen in Lucerne, Switzerland, where the lake paddle boat Rigi, a 138 ft iron-hulled vessel built in 1847 by Ditchburn & Mare, London, is preserved. Her bow lines can truly be described as knife-like, with hollow waterlines and hollow sections. There seems to have been more freedom of thought applied to steamship design, possibly because their lines could  be considered from the fact that their normal position was upright, both sides of the ship being symmetrical, whereas with a sailing vessel, although the lines are symmetrical when upright, they become asymmetrical with the vessel in its usual position heeled over to one side.