Unrestricted service

Unrestricted service is the class notation for a ship designed and built to operate worldwide with no geographic or seasonal limit on its trading area. It sets the structural and stability baseline: the hull is designed to the full North Atlantic wave loads of IACS UR S11 and Recommendation No. 34, and the freeboard is assigned under the full 1966 Load Line Convention zones. Restricted-service notations (coastal, sheltered water, or a named sea area) permit reduced wave loads and lighter scantlings because the ship will not see the worst open-ocean conditions, in exchange for a binding trading-area limit on the certificate. Unrestricted is the default expectation for ocean-going merchant tonnage and the one against which restricted reductions are measured.