LOA, beam and draft — the three dimensions of every ship

Length overall (LOA) is the full length of the hull, extreme point to extreme point — the number every silhouette on this site is scaled by. It differs from length between perpendiculars, a naval-architecture measure that excludes overhangs; record boards, berths and this site all use LOA.

Beam is the width. For most ships the published figure is the moulded beam of the hull; cruise ships complicate it, because superstructure, bridge wings and lifeboats can overhang well beyond — Oasis-class ships have a 47-metre hull but spread past 60 metres above it. Where a maximum beam matters (as it does at canal locks), the spec tables here say which figure they carry.

Draft is the depth of hull below the waterline, and it is the dimension that kills. It varies with loading — a laden ULCC sits ten metres deeper than an empty one — and it decided the fate of the giants: Pierre Guillaumat's 29 laden metres closed nearly every port on Earth to her. Air draft, the height above water, matters at bridges: Icon-class ships were designed to squeeze under Denmark's Great Belt Bridge on delivery.