Mineral category

Draft survey for minerals refers to a method of calculating cargo weight by measuring the difference in draft of a ship before and after loading or unloading mineral products (such as coal, iron ore, copper concentrate, etc.), combined with ship information and water density data. It is applicable to the trade handover of mineral products transported by bulk carriers.

operating steps

1. Measure the six-sided draft. Record the draft readings at six locations on the ship, including the bow (F), midship (M), and stern (A). Use draft marks or electronic draft gauges (such as Echo Sounder) to read the data.

2. Calculate the average draft and correct for the effects of trim and list.

3. Check the displacement. Based on the average draft, refer to the Hydrostatic Table of the ship to obtain the current displacement.

4. Calibration of water density: Measure the density (Density) of the harbor water.

5. Calculate the weight of the cargo. After deducting the consumption of fuel and fresh water during the loading/unloading process, the net weight of the mineral products is finally obtained.