In draught survey operation several parties are involved and it is to advantage of each party to join the efforts to increase the accuracy. The parties involved are The buyers, the sellers, the charterers, the terminals and vessel’s staff.
Assuming that buyers, sellers and charterers are equally concerned about the correct weight of cargo, also the master (respectively chief officer to whom the responsibility of cargo weight is delegated) shortages and discrepancy may be a problem.
In order to avoid this, it is strongly recommended that, once a vessel is nominated, a telex be sent to the master informing that the bill of lading weight will be established by draught survey. This, in order to indicate that his vessel is to meet certain requirements at the time of arrival at load/disport.
The weight of cargo will be determined by draft survey, consequently:
1. Vessel shall arrive at the loading (or unloading) port with a trim not exceeding her ballast tank trim correction tables and without list (in any case the list must not exceed ½ degrees).
2. Vessel shall furnish the following documents which are approved otherwise suitably verified as being applicable to the ship:
(a) Hydrostatic tables (or curves)
(b) Trim and stability booklet
(c) Calibration, tables for all tanks – ballast, bunker, freshwater, slops, etc., with correction for trim
(d) General arrangement plan
(e) Load line certificate
(f) Record of the ship’s constant
3. The draft marks, forward, aft, and amidships, the deck line, and the plimsoll marks, all port and starboard shall be clearly legible and cut in, raised or marked with weld bead on the shell plating.
4. Vessel shall no take, pump out, or switch from one tank to another, ballast, freshwater or bunkers while draught survey is carried out.
5. It should be avoided having ballast in one of the holds. Otherwise loading operation not to be started before hold is pump out completely.
6. Unless properly calibrated, the ballast tank should, or be mad empty, before survey starts. (this individually per tank). Sounding pipe must be intact, free of blockage and readily accessible.
7. Loading/unloading operation should not start until the draft readings and density readings have been completed. Tank sounding shall be made immediately thereafter. The condition of ship or the availability of ship’s personnel should not interfere with or delay the timely completion of this operation.
8. Notice of readiness will be accepted only when the vessel is ready for a draught survey and complies with the above mentioned points and no other condition may exist on board which will interfere with a timely and accurate draft survey.
9. Officer and crew are requested to offer the surveyor their fullest cooperation in the performance of his duties.
Source : Code of Uniform Standards and Procedures for the Performance Draught Surveys of Coal Cargoes – UN ECE