How is the minimum diameter of a port turning basin determined?

It should be at least 1.5 to 2.0 times the overall length (LOA) of the largest design vessel if tug assistance is available, and up to 4.0 times LOA without tugs.

What is the recommended width for an approach channel?

For single-lane traffic, it is typically 3 to 4 times the beam of the largest design vessel; for two-lane traffic, it is 5 to 7 times the beam.

How much Under Keel Clearance (UKC) is required for safe navigation?

A minimum of 10% of the vessel's maximum draft is generally required, though this must be adjusted for squat, tide, and wave action.

What clearance is required between two ships moored continuously in a line?

A clearance of 15m to 25m is standard, depending on the sizes of the mooring vessels and their required operational gaps.

IS 4651 Part 6

: 1980

Planning and Design of Ports and Harbours - Quay Walls

CurrentSpecializedCode of PracticeBIMStructural Engineering · Coastal and Marine Engineering

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This standard outlines the planning, layout, and functional requirements for the design of ports and harbours. It provides critical geometrical parameters for marine infrastructure including approach channels, turning basins, and berths to ensure safe vessel navigation, mooring, and efficient cargo operations.

Provides guidelines for the design and construction of quay walls in port and harbour developments.

Quick Reference Values

Minimum turning basin diameter (with tugs)1.5 to 2.0 x LOA (Length Overall of design vessel)

Minimum turning basin diameter (without tugs)3.0 to 4.0 x LOA

Approach channel width (single lane)3 to 4 times beam of the largest vessel

Approach channel width (two lane)5 to 7 times beam of the largest vessel

Minimum under keel clearance (UKC)10% of maximum vessel draft

Clearance between moored vessels15m to 25m depending on vessel size

Key Formulas

Required Channel Depth = Maximum Vessel Draft + Squat + Wave Response Allowance + Under Keel Clearance

Practical Notes

Always incorporate vessel squat (sinkage) and wave-induced heave/pitch when calculating the safe navigable depth of approach channels.

Master planning should account for the historical trend of increasing vessel sizes (LOA, beam, and draft) to prevent premature obsolescence of port facilities.

Turning basin dimensions heavily depend on the maneuverability of the design vessel and the continuous availability of assisting tugboats.