---
title: "Draught (or draft)"
description: "Depth to which a ship is immersed in water. The depth varies according to the design of the ship and will be greater or lesser depending not only on the weight"
url: "https://oceancargo.co.uk/shipping-terms/draught-or-draft"
date: "2026-05-26T10:13:36+00:00"
language: "en-GB"
---

![Ocean Cargo](https://oceancargo.co.uk/images/GenPics/OCs-Customs-Brokerage.webp)

 # Understanding Draught (Draft) in Maritime Shipping: A Comprehensive Guide

## What is Draught (Draft)? Defining a Critical Maritime Measurement

In the complex world of global shipping, precision is paramount. Among the many critical measurements that govern the safe and efficient movement of cargo by sea, **draught** (often spelled **draft** in American English) stands out as fundamental. At its core, draught refers to the vertical distance between the waterline and the bottom of the ship's hull (keel). Essentially, it's the depth to which a ship is immersed in water.

This seemingly simple measurement is, in fact, a dynamic and crucial factor that dictates where a vessel can safely navigate, berth, and load or unload cargo. For freight forwarders like Ocean Cargo, understanding a ship's draught is not just technical knowledge; it's a cornerstone of effective logistics planning and risk management.

The depth of immersion is not static. It varies significantly based on several key factors, including the ship's design, its total weight (including cargo, fuel, and provisions), and even the density of the water in which it floats. These variables collectively determine the vessel's operational limits and, consequently, the viability of specific shipping routes and port calls.

## Why Draught Matters: Impact on Shipping Operations and Safety

The importance of draught extends across virtually every aspect of maritime operations. Ignoring or miscalculating a vessel's draught can lead to severe consequences, from grounding incidents to significant delays and financial penalties. Here’s why it’s so critical:

- **Navigational Safety:** The most obvious reason is to prevent grounding. Ships must maintain sufficient clearance between their keel and the seabed. Channels, rivers, and port entrances often have depth restrictions, and a ship's draught directly determines whether it can safely pass through.
- **Port Accessibility:** Many ports and terminals have maximum draught limits for vessels. Deeper draught ships require deeper berths and approach channels. Ocean Cargo meticulously plans routes and selects vessels that are compatible with the destination port's infrastructure, ensuring seamless [sea freight services](https://oceancargo.co.uk/services/sea-freight/).
- **Cargo Capacity:** A ship's draught increases with the amount of cargo it carries. Understanding the maximum permissible draught allows for optimal loading without exceeding safety limits or port restrictions. This directly impacts the efficiency and cost-effectiveness of [Full Container Load (FCL)](https://oceancargo.co.uk/services/full-container-load-fcl/) and [Less than Container Load (LCL)](https://oceancargo.co.uk/services/less-than-container-load-lcl/) shipments.
- **Stability:** While not directly a measure of stability, draught is intrinsically linked. A ship's stability characteristics change with its loading condition and, by extension, its draught.
- **Environmental Factors:** Water density plays a significant role. Ships float higher in denser saltwater than in less dense freshwater. This means a ship's draught will be greater when moving from the ocean into a freshwater river or lake, even with the same load.

## Factors Influencing a Ship's Draught

As a dynamic measurement, a ship's draught is constantly influenced by a combination of internal and external factors:

### Ship Design and Construction

- **Hull Shape:** The fundamental design of a ship's hull dictates how it displaces water. Wider, flatter hulls generally have a shallower draught for a given displacement compared to narrower, deeper hulls.
- **Size and Type:** Different vessel types are designed for different purposes and, consequently, have varying draughts. For instance, a large container ship designed for transoceanic voyages will have a much deeper draught than a shallow-draught river barge.
- **Light Draught:** This refers to the draught of a ship when it is empty, without cargo, fuel, or provisions. It's the minimum immersion.

### Weight and Load Distribution

- **Cargo Weight:** This is the most significant variable. As cargo is loaded, the ship sinks deeper into the water, increasing its draught. Conversely, as cargo is discharged, the draught decreases.
- **Ballast Water:** Ships use ballast water to maintain stability and trim (the angle of the ship relative to the water) when lightly loaded. Adding or removing ballast water directly impacts the ship's weight and, therefore, its draught.
- **Fuel, Provisions, and Stores:** The weight of bunkers (fuel), fresh water, crew, and provisions also contributes to the overall displacement and draught.

### Environmental Conditions

- **Water Density:** This is a crucial, often overlooked factor. Ships float higher in denser water (e.g., saltwater, which has a density of approximately 1.025 tonnes/m³) and lower in less dense water (e.g., freshwater, with a density of 1.000 tonnes/m³). This difference means a ship will have a greater draught in freshwater than in saltwater, even with the same total weight. This is particularly important when vessels transition between oceans and inland waterways.
- **Temperature:** Water density also varies slightly with temperature, though this effect is generally less significant than salinity.
- **Waves and Swell:** While not affecting the static draught, rough seas can cause a ship to "pitch" and "heave," temporarily increasing its effective draught at certain points, which must be considered for under-keel clearance.

## Types of Draught Measurements

To ensure accuracy and safety, several specific draught measurements are used in maritime operations:

- **Forward Draught:** The draught measured at the bow (front) of the ship.
- **Aft Draught:** The draught measured at the stern (rear) of the ship.
- **Midship Draught:** The draught measured at the mid-point of the ship's length.
- **Mean Draught:** The average of the forward and aft draughts. This is often the most commonly referenced draught for general purposes.
- **Maximum Draught (Design Draught):** The deepest draught for which a ship is designed, typically corresponding to its maximum load line.
- **Scantling Draught:** The maximum draught to which a ship can be loaded, as determined by its structural strength.
- **Air Draught:** While not a measure of immersion, air draught is the vertical distance from the waterline to the highest point of the ship (e.g., mast, funnel). This is critical for passing under bridges or overhead power lines.

Draught marks, typically painted on the bow, stern, and sometimes amidships, allow crew members and port authorities to visually determine the ship's immersion. These marks are usually in decimetres or feet.

## Draught and Incoterms: Understanding Responsibilities

While Incoterms primarily define the responsibilities for costs and risks between buyer and seller, the underlying logistics, including draught considerations, are crucial for successful execution. For example, under [FOB (Free On Board)](https://oceancargo.co.uk/incoterms/fob-free-on-board/), the seller is responsible for loading the goods onto the vessel nominated by the buyer. If the buyer nominates a vessel that cannot safely berth due to draught restrictions, it can lead to significant delays and additional costs.

Ocean Cargo's expertise in [customs compliance](https://oceancargo.co.uk/services/customs-compliance/) and overall logistics planning ensures that all such operational details, including vessel suitability and port capabilities, are thoroughly vetted, regardless of the chosen Incoterm. Our team provides comprehensive advice to mitigate risks associated with vessel selection and port accessibility, ensuring your cargo reaches its destination efficiently.

## Ocean Cargo: Navigating the Depths of Global Logistics

At Ocean Cargo, our 25+ years of experience in freight forwarding means we understand the intricate details that make or break a shipment. From calculating precise draught requirements for specific vessels and ports to managing complex [sea freight to the USA](https://oceancargo.co.uk/countries/usa/sea-freight-usa) or specialist [wind turbine components to Australia](https://oceancargo.co.uk/countries/australia/wind-turbine-components-blades-nacelles-tower-sections-australia), our team ensures every variable is accounted for.

We don't just move cargo; we provide strategic partnerships that simplify complex supply chains. Our hands-on, consultative approach means we're always on top of the operational details, including the critical measurement of draught, to guarantee reliability, precision, and trust in every shipment. Whether you're shipping [excavators and diggers to the UAE](https://oceancargo.co.uk/countries/uae/excavators-diggers-uae) or general cargo via [air freight](https://oceancargo.co.uk/services/air-freight/), our commitment to integrity and flawless execution remains unwavering.

## Frequently Asked Questions About Draught

#### What is the difference between draught and depth?

Draught (or draft) is the vertical distance from the waterline to the bottom of the ship's hull (keel). Depth, in a maritime context, usually refers to the vertical distance from the ship's main deck to the bottom of the hull, or the depth of a channel or port.

#### How does water density affect a ship's draught?

A ship will float higher in denser water (like saltwater) and lower in less dense water (like freshwater). This means a ship will have a greater draught when moving from saltwater to freshwater, even if its total weight remains the same. This is a critical consideration for vessels transiting between oceans and rivers.

#### Why is air draught important?

Air draught is the vertical distance from the waterline to the highest point of the ship. It's crucial for ensuring a vessel can safely pass under bridges, overhead power lines, or other aerial obstructions without collision. It's a complementary measurement to the underwater draught.

#### Can a ship's draught be changed?

Yes, a ship's draught changes dynamically. It increases as cargo, fuel, and provisions are loaded, and decreases as they are discharged. Ballast water can also be added or removed to adjust the draught and trim for stability and navigation.

#### How does Ocean Cargo account for draught in its logistics planning?

Ocean Cargo's expert team meticulously considers vessel draught in conjunction with port and channel depth restrictions when planning [sea freight](https://oceancargo.co.uk/services/sea-freight/) routes. This ensures that the selected vessel is suitable for both the origin and destination ports, preventing delays, ensuring safety, and optimising cargo capacity for our clients' shipments, whether it's [sea freight to Canada](https://oceancargo.co.uk/countries/canada/sea-freight-canada) or any other global destination.

### Ready to simplify your global logistics?

Get advice and a quote for your next shipment. Contact the Ocean Cargo team to start shipping.

[Freight Quote](https://oceancargo.co.uk/contact-us)

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