Under keel clearance
height of water under a keel
In seafaring, under keel clearance (UKC) is the vertical distance between seabed and the keel or hull of a ship.
It is used to ensure sufficient navigable water is available for ships at sea.
Master mariners should ensure there is sufficient minimum UKC for their ships; ports should ensure sufficient minimum UKC for the type and draft of ships due to arrive in the port. Ships typically calculate their UKC to meet criteria for ports to minimise the risk of maritime incidents. The minimum UKC determined includes a safety margin.
Methods of calculation
At a basic level, it is typically calculated in metres using the formula:
UKC = Charted Depth − Draft -/+ Height of Tide
Ship masters and deck officers can obtain the depth of water from Electronic navigational charts. More dynamic or advanced calculations include safety margins for manoeuvring effects and squat.
Computer systems and software can be used to manage and calculate UKC for ships and ports. These include systems that dynamically manage UKC using models, forecasting and calculations.
The International Hydrographic Organization (IHO) sets a Standard for UKC Management for software and systems: S-129 Under Keel Clearance Management.
The public source identifies “Under keel clearance” as height of water under a keel. This brief keeps that definition visible, then builds a research path around keel, clearance and height.
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This entry incorporates text from “Under keel clearance” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.