In various texts about the spice trade in Venice during the medieval era, the price of spices are given in ducats per cargo. The value of ducats are easy to convert to modern day currencies using their gold content, however I have found no records on the weight of a cargo. Can anyone shed light on this?
Sorry to say there's no set value - these documents are referring to the size of the stuff the ship is carrying. Venetian merchantmen were not uniform, and thus the volume of the content would change drastically.
Also, even if you know the value of the gold, that just tells you what it's worth today, not what it was worth then.