Draft Survey

A maritime draft survey is a specific type of survey conducted on ships or vessels to determine the amount of cargo loaded or discharged. The term "draft" refers to the depth of a ship's hull below the waterline, and a draft survey involves measuring this depth at various points on the ship before and after loading or unloading cargo.


Here's an overview of how a maritime draft survey typically works:

Before Loading/Discharging:

- The initial draft of the ship is measured at various points along its length, typically at the bow (front), amidships (middle), and stern (rear). This is known as the "initial draft" or "pre-loading draft."

During Loading/Discharging:

- Cargo is loaded onto or discharged from the ship.

- As the cargo is added or removed, the ship's draft changes.

After Loading/Discharging:

- Once loading or discharging is complete, the draft of the ship is measured again at the same points as in step 1. This is known as the "final draft" or "post-loading draft."

Draft Survey Calculation:

- The difference between the initial draft and the final draft, along with the ship's characteristics (such as its dimensions and the density of water), is used to calculate the amount of cargo loaded or discharged.

The draft survey is a common method for determining cargo quantity, especially when it is not feasible or practical to weigh the cargo directly. It is crucial for ensuring that the ship is loaded within safe operating limits and that the cargo quantity matches the documentation (bills of lading, shipping manifests, etc.).

Accuracy in draft surveys is essential for various reasons, including compliance with international regulations, proper stowage of cargo, and preventing overloading, which can compromise the safety and stability of the vessel. Trained surveyors or ship officers typically perform draft surveys, and accurate measurements are crucial for both operational and legal reasons in the maritime industry.

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