Threshold

A threshold in maritime regulation is the size, length, or voyage criterion that triggers a rule’s application. SOLAS uses gross tonnage, length, and passenger count as cut-offs: most of the Convention applies to cargo ships of 500 gross tonnage and above on international voyages, the noise and construction-file rules use 1,600 GT and 150 m, and life-saving and security provisions scale by passenger numbers and 24 m length. Gross tonnage is fixed by the Tonnage Convention 1969 and length by the Load Lines Convention, so the measured value that decides applicability is itself a convention output. Ships just below a threshold often face national equivalents.