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Draught calculation

Tue Apr 26, 2005 6:33 pm

like to know in 1 mtr river draft how much tonnage can load.

Tue Apr 26, 2005 7:28 pm

Complex question. When empty, the boat or barge already draws some water from its own weight.

If the sides are straight in the empty condition, as cargo is loaded, the water displaced is the surface area at the waterline x distance submerged. That displacement multiplied by the density of water has to match the tonnes of cargo.

Fresh water at 4 degrees C is 1 tonne per cubic meter. Actual temperature or ocean water (salinity) affect the calculation slightly.

Bottom line, you have to know the waterline area of the vessel, and the change in waterline area as the draft increases from empty draft. It obviously varies from vessel to vessel, and the only general rule is a tonne of cargo has to be offset by a tonne of additional water displaced

More info

List of all units you can convert online
Metric conversion
Convert grams to cups
Grams to milliliters
Imperial vs US Customary
History of measurement