Why not board the ship as a crew member? As in you would get a few silver for the voyage. No decision on where the ship is going or when it leaves. And only available if a noble is embarking at the time. The adventurer would then get an option while traveling on which ship they want to join, I am not sure what information would be given, perhaps the coast embarking from, the noble embarking and the unit size and type. The amount of silver earned would be based on the unit type and size. Again, this should not be a very large amount of silver (notice 'silver' not gold) per day.
