Draft Survey

Draft Survey

A draught survey is a means to assess the weight of the cargo loaded on or discharged from a vessel.

Our surveyor will assess the actual displacement, before and after loading or discharging, and the difference between two displacements. This will be corrected with the consumables used or bunkers taken on board during loading or discharge. The result represents the weight of the cargo.

The displacement will be assessed in accordance with international guidelines and consists of an initial and final survey. Both survey results will be entered in a computer-based programme, which will calculate the final figures.

The draught survey is the way the weight of a cargo on board a vessel is measured. Specially trained and highly qualified inspectors employed by Inspectorate are used to the complexities of determining the weight of cargoes on board a vessel. There are many elements and variable to be taken into account. For example, the draught marks allow a draught surveyor to measure how deep the vessel lies in the water which permits the displacement of the vessel and its cargo to be calculated.

However, there are many factors here that also impact on the vessel. These include the salinity of the harbour water, which will vary from port to port. On board measurements need to be taken from the ballast tanks to assess the impact of those on vessel weight. The ballast can have a significant impact depending on the density of the liquid used; seawater has a different density to fresh water. Inspectors will need to establish the ‘constant’, which is difference between the theoretical and the calculated weight of the vessel weight of the vessel and is made up of various weights such as sludge, stores and the crew. This forms part of the vessel’s history.

Inspectorate’s inspectors determine the weight of cargoes at ports across the world and are highly regarded for their expertise.