MARITIME – PORT, HARBOUR & CHANNEL OPERATION CALCULATOR
Under Keel Clearance Channel
A precise tool.
What is the Under Keel Clearance Channel & How does it work?
Under‑keel clearance (UKC) is the vertical distance between the deepest point of a vessel’s hull and the seabed. Maintaining an adequate UKC is essential for safe navigation, especially in dredged channels where the water depth is limited and may vary with tides. The UKC is calculated by subtracting the vessel’s draft and any required safety margin from the effective water depth, which includes the static depth of the channel plus the current tide height. This ensures that even when the vessel rides over a wave or experiences squat, there remains a buffer before grounding. The resulting value guides operational decisions such as timing of passage, speed restrictions, and whether additional dredging is needed. A typical minimum UKC for commercial vessels ranges from 0.5 m to 1.0 m, depending on vessel type and local regulations.
U = D + H_{text{tide}} – T – S
U = under‑keel clearance (m)
D = channel water depth (m)
H_{text{tide}} = tide height above chart datum (m)
T = vessel draft (m)
S = safety margin (m)
D = channel water depth (m)
H_{text{tide}} = tide height above chart datum (m)
T = vessel draft (m)
S = safety margin (m)
Parameters
Result
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Frequently Asked Questions
What is under-keel clearance?
Under-keel clearance (UKC) is the vertical distance between a ship’s hull and the seabed, crucial for safe passage.
How do I calculate UKC?
Subtract your vessel’s draft and safety margin from the effective water depth to determine UKC.
Why is UKC important?
UKC ensures safe navigation, especially in channels with limited or variable water depths.
What factors affect UKC?
Factors include the vessel’s draft, safety margin, static depth of the channel, and current tide height.
How do tides affect UKC?
Tides change the effective water depth, impacting UKC and requiring adjustments for safe passage.
What is a safety margin in UKC calculations?
A safety margin is added to the vessel’s draft to account for uncertainties and ensure a safe clearance.
Can I use this calculator for any vessel type?
Yes, but you should input accurate data specific to your vessel’s draft and requirements.
Results are for informational purposes only and do not constitute professional advice.