SIR ROBERT SEPPINGS

Unicorn was built under the supervision of Sir Robert Seppings, the Surveyor of the Navy 1813-1832, at a time when the shortage of timber and the availability of iron was beginning to affect the way ships were built.

Unicorn represents the last great flourish of wooden shipbuilding and illustrates the birth of the iron steamship.

Seppings took advantage of the availability, strength and compactness of iron and introduced new methods of construction which greatly strengthened wooden ships.

A truss of 'diagonal riders' stiffened the hull	A truss of ‘diagonal riders’ stiffened a ship’s hull with iron straps.
The framing of Seppings' circular stern	A ‘circular stern’ was much stronger and allowed the guns a better arc of fire.
The complex framing of a conventional transom stern
Unicorn's iron 'knees'	Iron ‘knees’ secured the deck beams to the ship’s side frames, in place of conventional wooden knees which had to be cut from specially grown timber.
A conventional frigate compared with the much longer ship made possible by the 'Seppings' system of construction	The complete ‘Seppings’ system integrated several other structural innovations and was so effective that it allowed wooden ships to be built strong enough to stand the weight of heavy steam engines, boilers and coal, and also long enough to provide the extra space needed for these.
WRS 2010