Hatch Cover Deflection Limit (UR S21)
Maximum permissible mid-span deflection of a weather-deck hatch cover: L/200 per IACS UR S21.
L/200 limit
75mm
Compliance
OK (≤ L/200 = 75 mm)
Formula, assumptions, and limits
Simply supported hatch cover under design pressure. Bulk carriers (IACS UR S21A enhancement) have additional sea-load factors and sloshing-pressure checks for partially loaded holds.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Unsupported span | m | hatch GA | |
| Mid-span deflection | mm | measurement or FE analysis |