The boats are built of pine and oak, and their length can vary from 8-18 “båtalner” (one “båtalen” is 55 cm, so a total length of 4.5-10.0 metres). The most common sizes are the færing for two pairs of oars (9-11 “båtalner” or 5-6 metres) and the seksæring for three pairs of oars (11-13 “båtalner” or 6-7 metres), but you can also find both smaller and larger versions: the æring for one pair of oars (8-9 “båtalner” or 4.5-5 metres), the åttring for four pairs of oars (12.5-14 “båtalner” or 6.9-7.7 metres) and the laromsbåt, a larger boat allowing for transport of cargo (12.5-18 “båtalner” or 6.9-10 metres). The four-oared “færing” boats are built with three strakes and three cross-braces with cross-beams over the two foremost strakes. Larger boats (usually boats from a length of 11.5 “båtalner” or 6.3 metres) can also have more cross-braces, two-part “børabord” (the broadest strakes) and two-part gunwale strakes.
The capping runs inside the boat along the upper edge of the gunwale strake from rib to rib. The exterior of a garboard strake on an Oselvar boat is concave and twists from almost vertical to almost horizontal where the garboard strake meets the bottom strake and broadest strake. The garboard strakes are therefore twisted, like a propeller blade or perhaps a plough share. During construction, the boat builder is careful to select planks in pairs, so that the elasticity on both sides of the boat is as equal as possible.
Over time, boat builders and boat users have developed the boat type together so that each boat is best suited to a certain area of use. With sports use, this has been continued: in addition to the utility boat, you can now find both specialised rowing boats for racing and specially built sailing boats for racing.