The Customs House is authorized by Resolutions 2914/94 and 2111/91 to control the weight of solid homogeneous cargoes via 'draft survey' methods. Liquid bulk cargoes are expected from this method and ships tank calibration tables are used to check cargo quantities. It should be noted that as per Resolution 4990/86 draft surveys can be ordered on barges carrying export transit cargo from Paraguay which have not been appropriately sealed. Bills of lading weight is as per Customs figures, and Customs figures are the same as shore figures.
Draft surveys are carried out when:
a) no alternative means exist to weigh bulk cargo
b) upon request of an interested party
c) at Customs House discretion
When performed by Customs House they usually designate two inspectors from their technical staff.
All expenses connected with these surveys, such as fares, board, lodgings, overtime, etc, are for the account of the party ordering to control (importer, exporter). In 'ex-officio' or counter-verifications, expenses involved, from a point of view of service only, are for the account of the Customs House.
Vessels are required to offer full assistance in connection with all procedures related to a draft survey, such as producing stability information book (details in metric system as per IMO recommendations) information pertinent to cargo on board, and to the assist with the sounding of tanks containing non cargo liquid weights and also provide pilot ladders a launch and proper illumination, etc. In this respect ships Agents are recommended to see that the aforementioned is coordinated in a timely and smooth manner, as they can also be held responsible for any setbacks in carrying out such surveys.
Vessels must report, on Customs forms, the basic date required in connection with 'Deadweight Surveys' or 'Draft Surveys' i.e. forms OM 1606B-1606C-1607B- and 1586. The habitual form used prior to commencement of loading/unloading operations is form OM 1606 which must be considered as a sworn statement in connection with information given as to the actual drafts, non cargo weights on board (solid & liquid) plus an as close as possible estimation of the ships so called 'constant' and that draft and load-line marks are correctly positioned and painted. Also that information contained on plans and tank and hydrostatic tables has been checked and is in force. This form is to be signed by the Ships Chief Officer/Master and in signing it they are bound to the contents of Customs Regulation 2111/91.
Since use of the draft survey method for the determination of either weight loaded or unloaded has certain limitations due to the number of factors and measurements involved, for the sole purpose of establishing limits of accuracy, as to results obtained, a tolerance equal to the ships TPI or a maximum of 6 per mil of the manifest cargo weight (whichever is greater) is permitted. i.e.: if cargo manifested is 30.000 ton and TPI=100 then 180 ton (30.000 x 0.006) is permitted. On the other hand if the cargo had been 10.000 ton a tolerance of 100 ton equal to the TPI would have been permitted since 10.000 x 0.005=60 ton.
Should the result as per draft survey lie within the said tolerance, then for customs purposes only, the declared quantity is taken as valid. However, should the weight as per 'draft survey' exceed the declared weight by more than the allowed tolerance (taking into account any legal tolerance that may be allowed for the class of cargo) then the former is applicable and the tolerance is not taken into account. Should the difference, adjusted for any other authorized tolerance, between draft survey and declared weights be greater than 4% it will lead to a Customs inquiry and possible fines being levied on the ship. In certain cases attending Customs officers have been established bulk quantity by Deadweight and not comparison of Displacements.
It is to be noted that in the past numerous discrepancies have arisen from errors in the use of this indirect method of weighing, hence experience recommended that a registered surveyor be in attendance, either on behalf of the ship or shipper, to ensure that the survey is carried out in satisfactory manner. This aspect has been contemplated by a standing Customs regulation, therefore a party with a legitimate interest in cargo, can appoint a registered surveyor, who in turn is entitled to add remarks on the appropriate form in connection with circumstances surrounding the draft survey should discrepancies exist. If none are added then the information and results as stated are taken as final.
Ships calling at more than one port in order to handle solid bulk cargoes are still subject to the above type of control and the filling in of the appropriate forms. The Centro de Navegacion has put forward various applications to Customs House authorities in order to either abolish this system or to discourage its use for documentary or customs purposes, unless otherwise agreed upon by carriers and shippers and included as a C/P clause.
Liquid bulk cargoes are controlled by a body of official measurers appointed from Customs House personnel. They either sound or take ullages of cargo tanks in company of a ships officer and/or other attending surveyors and by the use of appropriate tank tables and applicable corrections, establish the amount of liquid bulk cargo on board. The 6 per mil tolerance mentioned above is also applicable in the case of liquid cargoes. Also for liquid cargoes B/L's figures are as per customs figures, and custom figures are shore figures. If shore tanks are not bonded ones, ship figures are accepted. These controls are exercised on import, export and lightened liquid cargoes. They may also be applied to barges carrying ships bunkering fuels.
It should be noted that if certain events, either accidental or not, tend to hinder the exactness of control methods used, it is convenient to add a short and clear remark to this effect on the appropriate form. It should be noted as well as sampling of either solid or liquid cargoes plays an important part in the above controls. Close coordination by Agents in connection with measurement of liquid cargoes and the intervening parties is of utmost importance.