Afaik, historically they switched from fast ships to bigger, slow ones to minimize fuel use per cargo tonnage. At the beginning of the 'standardized container a

Afaik, historically they switched from fast ships to bigger, slow ones to minimize fuel use per cargo tonnage. At the beginning of the 'standardized container age' there were fast vessels but they lost out to the fuel saving spiral. If we're just bullshitting, more autonomous sailing vessels that mainly use streams and are automated could be used (like some autonomous little robot floats using wind for propulsion and the sun to power their electronics and small motors crossing the Pacific/Atlantic). But in contrast to the small robotic boats, they won't be able to correct their vector using solar power. If there are goods that can arrive whenever but need to be cheap, maybe that's an option - but only if the ship can work without maintenance underway, which it probably can't during its entire lifetime. Edit: The crew is there to make a ship work even though it needs maintenance.