Under Keel Clearance
Under Keel Clearance – the distance between the deepest point of the vessel’s hull and the sea bed.
UKC – Under Keel Clearance
Voyage Plan – a document prepared by the Navigation Officer, giving details about the intended voyage.The Navigation Officer is responsible for ensuring that correct UKC is applied at the various stages of a voyage, and instructed by the Master and/or guided by this procedure.
The Master is ultimately responsible for safety of the vessel, and he shall verify that the information is the Passage Plan is correct, before approving the plan in writing.
The OOW shall check prior to arriving at positions where minimum UKC is expected, that the calculated UKC is valid for the current conditions.In determing the UKC, the Master shall take into account all factors that have influence on the actual UKC, these factors include, but are not limited to the following;
1. The effect of Squat.
2. Environmental conditions, e.g. the prevailing weather, height of swell, tidal height and range, athmospheric pressure, and changes in the density of sea and inland waters.
3. The nature and stability of the bottom (e.g. sand wave phenomena)
4. The vessel’s size and handeling caracteristics, and increase in draught due to heel.
5. The reliability of ship’s draught observations and calculations, including estimates of hogging or sagging.
6. The accuracy of Hydrographic data and tidal predictions.
7. Reduced depths over pipelines.
The Company has established following instructions for UKC which shall be followed by the Master. If the Master must deviate from these instructions, he shall inform the Company without delay, or otherwise proceed with extreme caution.
Minimum UKC for various areas of navigation:
1. Open Sea – minimum 6 meters
2. Narrow Channels – 15% of the deepest draught
3. In Port Navigation – 10% of the deepest draught (see Note A below)
4. Alongside Berth – Minimum 0,50 meter
In Port Navigation, if the vessel is required to reduce UKC below 10%, the Master must take full account of the factors listed above, which govern determination of a safe UKC.
A calculation form for UKC at various locations, taking into consideration the above parameters have been attached to this procedure. The Master may use this program when determining the UKC at various locations during a voyage, but he may also use other simplified methodes provided that this give the same result.
UKC calculations shall form a part of the Voyage Plan, and the OOW shall have a copy of the UKC calculations available when arriving at the location where UKC considerations must be observed