Gross tonnage

Gross tonnage is calculated by measuring a ship's volume (from keel to funnel, to the outside of the hull framing) and applying a mathematical formula.

Gross tonnage (often abbreviated as GT , G.T. or gt ) is a unitless index related to a ship's overall internal volume. Gross tonnage is different from gross register tonnage . ^{[ 1 ]} Neither gross tonnage nor gross register tonnage is a measure of the ship's displacement (mass) and should not be confused with terms such as deadweight tonnage or displacement .

Gross tonnage, along with net tonnage , was defined by The International Convention on Tonnage Measurement of Ships, 1969 , adopted by the International Maritime Organization in 1969, and came into force on July 18, 1982. These two measurements replaced gross register tonnage (GRT) and net register tonnage (NRT). Gross tonnage is calculated based on "the moulded volume of all enclosed spaces of the ship" and is used to determine things such as a ship's manning regulations, safety rules, registration fees and port dues, whereas the older gross register tonnage is a measure of the volume of certain enclosed spaces.

So I see gross weight is irrelevant for our purposes

Whereas DWT includes the weight of people,fuel, ballast , drinking water, stores,which is why actual cargo load is in this case I would guess a few thousand tons less-so w a DWT of 45590 or so means actual load it would pick up would be ca 40-41k tons?

Picking up part of orders 3-5?