Is it possible to calculate the amount of cargo on board of a vessel?


If I know they type of transported cargo (let’s say crude oil), is there a way of reliably estimating the amount of cargo on board of the vessel based on vessel’s technical parameters and navigation info? What data will I need to make such calculations? Is there a software or formula out there that is successful in doing it?

Thank you,

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I think you can draft of the vessel. Draft is the depth of the vessel’s submerged part in the water.

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Draft, or draught of the vessel is usually self-reported by the ship. For smaller vehicles, this can be a physical measurement. But for larger vessels a common method used to measure the draught of a vessel is through the use of a draught scale. This is a calibrated instrument that is attached to the side of the vessel and measures the water pressure exerted by the water displaced by the hull. The water pressure reading is then converted into a draught measurement using a calibration table.

Another, perhaps experimental approach is using satellite imagery to measure draught, and make inferences about the weight of cargo.

Satellite altimetry can provide accurate measurements of draught for large vessels such as cargo ships and tankers, as well as for vessels in remote areas where on-site measurements may be difficult or impossible. However, there are some limitations to this method. For example, satellite altimetry may not be able to accurately measure the draught of smaller vessels or those with irregular hull shapes, and it can be affected by factors such as wave height and sea state. Additionally, satellite altimetry data may have a delay of several hours or more, so it may not be suitable for real-time navigation or operational purposes.

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To do this calculation you have to know:

  • Displacement
  • Cargo type also density
  • Ballast water weight or volume and density of ballast water
  • Other all weights and constants
  • Drafts(Forward, Aft, Midship)
  • Trim
  • Sea water density or sea water salt and temprature

Also you have to know this calculations and vessels constants:

  • Draft correction
  • Trim correction
  • Displacement calculation
  • Density correction
  • So Draft Survey
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As @furkan-zblbl mentioned, to accurately calculate the amount of cargo on board a vessel, you will need to have a solid understanding of various parameters and vessel-specific constants. Once you have this information, you can use the draft survey method to estimate the cargo weight.

A draft survey is a widely-used method in the maritime industry to calculate the amount of cargo loaded or discharged from a vessel. It involves a complex set of calculations that take into account the vessel’s displacement, trim, drafts, and other factors to determine the weight of the cargo on board.

There are software programs available that can help you perform draft surveys and calculate the amount of cargo on board a vessel. These software programs can significantly simplify the process and reduce the potential for human error in calculations.

Keep in mind that although these software tools can be quite accurate, they rely on the input data you provide. It’s important to ensure that the input data, such as the vessel’s draft, trim, and displacement, is accurate and up-to-date. Additionally, it’s essential to understand the limitations of these software programs and the assumptions they make, as they may not be suitable for all types of vessels or cargo.

In summary, while it is possible to estimate the amount of cargo on board a vessel using technical parameters and navigation info, it requires a comprehensive understanding of the vessel’s specifications, the cargo type, and various environmental factors.

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Thank you guys for all your responses. Based on these I conclude that it is quite challenging to do. If I knew all those parameters and details about the ship, I might as well also find out the cargo it is carrying.


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