Udema

The udema was designed by the prolific naval architect Fredrik Henrik af Chapman for use in an area of mostly shallow waters and groups of islands and islets that extend from Stockholm all the way to the Gulf of Finland.

The udema was of an innovative new design with a single line of guns along the ship's centerline, a foreshadowing of the dreadnought battleships of the early 20th century.

The Swedes began building inshore flotillas of shallow-draft vessels, beginning with smaller versions of the traditional Mediterranean warships, the galleys.

[2] The Swedish military invested heavily in an "archipelago fleet" (skärgårdsflottan), a separate branch of the armed forces that organizationally belonged to the army.

It was in many ways a highly independent organization that attracted a social and cultural elite and enjoyed the protection of Gustav III after his 1772 coup that empowered him as an absolute monarch.

The result was four new vessels that combined the maneuverability of oar-powered galleys with the superior rigs and more comfortable living conditions of sailing ships: the udema, pojama, turuma and hemmema, named after the Finnish regions of Uusimaa ("Uudenmaan" in genitive form), Pohjanmaa, Turunmaa and Hämeenmaa (Tavastia).

[7] Torborg, built in 1772, had three additional 12-pounders, eleven in the centerline and two in the bow facing forwards, housed under a decked superstructure with gun ports, but with the rowing seats left undecked.

Rowers sat on the weather deck on either side of the main armament with the oar ports placed on a rectangular outrigger which improved their leverage.

The Royal Navy, its successor, later equipped the equivalent of sixth rates with oar ports on or below the gundeck as early as the 1660s.

[17] Historian Lars-Olof Berg suggests that the radical new design of rotating gun mounts, though somewhat of a disappointment in Swedish service, may have influenced shipbuilders in other countries.

Pivoting mounts were used in the US "gunboat navy" under Thomas Jefferson, even in much smaller craft, though they often proved risky since the recoil could destabilize vessels with a small displacement, especially if the guns were fired over the side.