The number of crew members would be a relatively easy thing to establish even if the ship were lost at sea. The sailors had to be paid. In some cases that would be a set amount of currency. In the case of whaling vessels it often took the form of a share of profits from the sale of whale oil.

In any event payroll records had to be maintained for the identities of the crew members and the amount of payment they were to receive. It would be a simple matter of presenting the payroll records into evidence to prove the number of crew members assigned to the ship.

The nature of the cargo would be a little more difficult. While a ship's manifest might show the type of cargo. The ship owner's compliance with the manifest is another matter.