Draft survey is used for weight determination of bulk cargoes. It is performed by reading of draft marks on vessel body before loading commencement and after loading completion. A surveyor calculted the cargo weight =(ship’s displacement)-(ballast water wight)-(fuel weight)-(fresh water weight)-(lightship displacement). Such calculation performed before and after cargo operations. The different in «cargo weight» is the loaded/discharged cargo weight.
Draft survey includes measurements of vessel draft (depth of the ship’s hull in water) by reading of cargo marks on vessel hull, measurement of seawater density, quantity determination of ballast water and other liquids, and calculation of cargo quantity using the vessel shipping documents. Each ship has hydrostatic tables and ballast water tank tables which are used by surveyor for volumes/weight calculation.
Our copmany performs Draft Surveys in most of Russian sea and river ports: Saint-Petersburg, Novorossiysk, Murmansk, Kaliningrad, Ust-Luga, Vyborg, Vysotsk, Vladivostok, Nakhodka, Vostochniy.