Under-Keel Clearance (UKC)
Net UKC = charted depth + tide − draft − squat − wave allowance − safety margin. The fundamental pilot-card number.
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Formula, assumptions, and limits
| Symbol | Meaning | Unit |
|---|---|---|
| Charted depth | m | |
| Tide height | m | |
| Static draft | m | |
| Dynamic squat | m | |
| Wave allowance | m | |
| Safety margin | m | |
| Under-keel clearance | m |
Source: IMO MSC.1/Circ.1421 - UKC guidelines; PIANC WG121 - Harbour approach design
In short
Net UKC = charted depth + tide \u2212 draft \u2212 squat \u2212 wave allowance \u2212 safety margin.