# Turning basin

*Last updated: 2026-09-09*

> A turning basin is the widened area of water in a port or approach channel where a vessel can reverse its heading through 180 degrees without endangering quay structures or other ships.

A turning basin is the widened area of water in a port or approach channel where a vessel can reverse its heading through 180 degrees without endangering quay structures or other ships. As a rule of thumb its diameter is one and a half to two times the vessel's length; strong wind, current or ice, or a vessel without bow thrusters, requires more room or tug assistance. Alongside water depth and quay length, the turning basin is therefore the third hard limit on the largest vessel a port can handle: a 400-metre container ship is of no use at the longest quay if it cannot turn inside the harbour. Upgrade projects for very large vessels consequently tend to combine quay works with widening the turning basin and deepening the approach.

**Source:** PIANC, Harbour Approach Channels – Design Guidelines (Report 121-2014)

## Quick Facts

| Property | Value |
|---|---|
| Term | Turning basin |
| Language | EN |
| Word count | 130 |
| Last updated | 2026-09-09 |
| Source | PIANC, Harbour Approach Channels – Design Guidelines (Report 121-2014) |

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