Boil-Off Rate
Abbreviation: BOR
Daily fraction of cryogenic cargo lost to boil-off, expressed as % of cargo mass per day.
In practice
Charterers verify BOR against the warranted rate at every voyage. The deck cadet records cargo-tank temperature and ullage at noon; the cargo officer logs daily evaporated mass. A persistent excursion above the warranted rate triggers a charter-party performance claim.
Regulatory detail & full definition
BOR is a guarantee figure in newbuild contracts. For LNG carriers, BOR < 0.15%/day is now standard for Q-Flex and Q-Max; older steam-turbine vessels run 0.20-0.25%/day. The rate varies with sea state, ambient temperature, and cargo level (sloshing). Charterers monitor BOR closely because it directly affects voyage economics.
Related
Source: Industry usage; IACS UR M77
High confidence
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