Panamax: the ship size class set by the 1914 locks
The Panamax size class, defined by the original Panama Canal lock chambers at 294.13 m length, 32.31 m beam and 12.04 m tropical fresh water draft.
Panamax is the ship size class defined by the original Panama Canal lock chambers, which admit vessels to 294.13 m length overall, 32.31 m beam and 12.04 m tropical fresh water draft under the Panama Canal Authority’s OP Notice to Shipping N-1-2026. The class is a canal category rather than a classification society or IMO category, and the 32.31 m beam is the binding dimension.
The full article will cover the origin of the limits in the 1914 chamber geometry, the 13-container-row deck that the beam limit produces, the Panamax bulk carrier and container ship as distinct design families, the operational maxima that sit below the definitional figures, and the way the class persisted on coal and grain routes that never approach the canal. It will also treat the Panamax Plus category, which the Authority applies to a Panamax-dimension vessel authorized above 12.12 m draft and charges as NeoPanamax.