IACS Rec. 47

IACS Recommendation 47, the Shipbuilding and Repair Quality Standard, sets the workmanship tolerances and acceptance criteria for hull-structure fabrication during newbuilding and for repairs in service. It applies to conventional merchant ships built from normal and higher-strength steels and is used where a yard or society has adopted no other national shipbuilding standard. Part A covers new construction: gas cutting, plate alignment, fairness, edge preparation, welding joint geometry, and remedial limits. Part B covers ship repairs, including welding, material substitution, and personnel qualification. A surveyor measures against Rec.47 to decide whether a misaligned joint, an undercut weld, or an out-of-fairness plate is accepted, corrected, or renewed.