IACS Recommendation 34

IACS Recommendation No. 34 provides the standard wave data used to derive wave loads in classification rules, a scatter diagram of significant wave height against zero-crossing period for the North Atlantic. The North Atlantic is chosen because it represents the most severe routine trading conditions, and the data include the effect of bad-weather avoidance for ships over 90 m. The recommendation pairs the scatter diagram with a wave spectrum (the updated revision uses a JONSWAP spectrum with a peak-enhancement factor of 1.5 and a cosine directional spreading) and a 25-year design return period. It underpins the wave bending moments in UR S11 and the direct load analyses in the Common Structural Rules.