Mandatory registration & tonnage measurement
According to Chapter 1 of the Swedish Maritime Code (SFS 1994:1009), a ship is a vessel having a length over all of at least twelve metres and a maximum breadth of at least four metres. Other vessels are called boats. According to Chapter 2, all Swedish ships shall be registered in the Register of Ships. The only exception are ships owned by the State and which are not used in commercial service. Note that this applies regardless of what the ship is used for, i.e., including recreational crafts that are considered ships according to the definition above. Boats in commercial service shall be registered in the Register of Boats if the hull length is at least five metres. The Maritime Registry keeps both the Register of Ships and the Register of Boats.
Mandatory tonnage measurement
All Swedish ships registered in the Register of Ships must be measured. The regulations applicable to tonnage measurement are found mainly in the Ordinance (SFS 1994:1162) on tonnage measurement. The Swedish Transport Agency performs tonnage measurements.