Under-Keel Clearance (UKC)
Net UKC = charted depth + tide − draft − squat − wave allowance − safety margin. The fundamental pilot-card number.
Net UKC
1.90m
Formula, assumptions, and limits
Port authorities typically require UKC ≥ 10 % of draft in coastal channels and ≥ 1.5 m on open-water approaches. Always measure tide on actual day (predicted + surge), not table nominal.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Charted depth | m | nautical chart | |
| Tide height | m | tide tables | |
| Static draft | m | loading computer | |
| Dynamic squat | m | Barrass / pilot | |
| Wave allowance | m | sea state | |
| Safety margin | m | SMS | |
| Under-keel clearance | m | result |