Sometimes the accuracy of Draft Survey is a big question, especially when the cargo loaded or discharged from the vessel shown extremely different weight with the references Weight Scale or Counter Weight. Unfortunately, the parties concerns would be doubt on to the weight resulted by Draft Survey, as they have been relying upon the mentioned scales for many years.
Draught Survey UN ECE: Code of Uniform Standards and Procedures
UN ECE was published the Factors Affecting Draft Survey as follows :
1- Incorrect hydrostatic information or draft marks: Investigations carried out in specially performed draft surveys have indicated that there can be significant errors in the determination of displacement due to typographical errors or arithmetical errors in the ship’s hydrostatic tables. This could be improved if the tables furnished to the surveyor bore an approval stamp by the flag government or the classification society. A number of years careless re-painting of draftmarks, especially if they have not been permanently marked on the hull, can cause erroneous readings. If there is any doubt, the draft marks should be re-sited at the next dry-docking.
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