Initial Inspection & Preparation

Before commencing the draft survey, our marine surveyors conduct a thorough initial inspection of the vessel. We ensure that all draft marks are visible, accessible, and accurately recorded. Additionally, we verify the quantities of ballast water, fuel, freshwater, and other liquids on board that may influence the vessel’s displacement and stability. This critical preparatory step ensures the reliability of all subsequent draft measurements and calculations.

Draft Readings (Before Loading/Discharge)

Our certified surveyors take accurate draft readings from the vessel’s forward, midship, and aft sections on both port and starboard sides—a total of six measurement points. These readings are essential for calculating the ship’s initial displacement before any cargo is loaded or discharged. By applying precise techniques and accounting for environmental conditions, we ensure a reliable baseline for the overall draft survey process.

Draft Survey Procedure

At VALENCIA Marine Services, we conduct draft surveys using a precise, internationally recognised methodology to determine the exact weight of cargo loaded or discharged from a vessel. Our certified marine surveyors follow a systematic process that includes 6-point draft readings, seawater density sampling, trim and list corrections, and hydrostatic table calculations. This ensures a high level of accuracy, traceability, and full compliance with maritime regulations, minimising discrepancies and supporting efficient cargo operations.

Water Density Measurement

To ensure precise cargo weight calculations, our team collects seawater samples from the vessel’s location—typically near the berth or anchorage—and measures the water density using a calibrated hydrometer. Since water density directly influences displacement calculations, this step is critical for achieving the highest level of accuracy in the draft survey. By accounting for local salinity and temperature conditions, we help eliminate potential discrepancies in weight assessment.

Initial Displacement Calculation

Using the vessel’s official hydrostatic tables, we calculate the ship’s displacement before cargo operations begin. Our surveyors apply all necessary corrections for water density, trim, and list to ensure an accurate assessment of the vessel’s condition. This corrected displacement value forms the baseline for determining the exact weight of cargo loaded or discharged, maintaining precision and compliance with industry standards.

Final Draft Readings (After Loading/Discharge)

After cargo operations are completed, our surveyors conduct a second set of draft readings from the same six reference points: forward, midship, and aft on both port and starboard sides. These measurements provide the vessel’s final displacement, which is essential for calculating the net weight of cargo loaded or discharged. By maintaining consistency and precision in both sets of readings, we ensure the reliability of the entire draft survey process.

Final Displacement Calculation & Cargo Weight

To determine the exact weight of cargo loaded or discharged, we calculate the difference between the vessel’s final and initial displacements. This net change reflects the cargo quantity handled. Our team then applies precise adjustments for ballast changes, fuel and freshwater consumption, and any other relevant variables affecting the vessel’s weight. This comprehensive approach ensures accurate cargo weight certification in full compliance with maritime industry standards.

Survey Report & Certification

All collected measurements, calculations, and corrections are compiled into a comprehensive Draft Survey Report, prepared and signed by our certified marine surveyors. This detailed document serves as the official record of cargo weight handled and is essential for shipping documentation, customs clearance, and potential dispute resolution. Our reports are delivered promptly in both digital and hard copy formats, ensuring transparency, traceability, and full compliance with maritime standards.