>>1648296All the problems of actually building masts tall enough to do anything to a ship that size or the crew and maintenance requirements aside, the sheer loss of cargo capacity would render it uneconomical even compared to synthetic fuels.
For the sails to do anything, you'd need them above the containers. As hight-limitations are a thing for most ports and structural limits are a thing at that size, you'd likely be limited in terms of cargo-hight. Additionally, any mast strong enough to propell such a ship would render the space beneath (including the are covered horizontally) unreachable for the container cranes. This would really eat into container-count.
Then there's the indirect loss. Life isn't always perfect weather. The diesel ships don't care. Except for some really bad storms, weather won't put them off their tight schedule. For a sail-ship, best of a schedule you can do is a rough estimate and on average, it's going to be pretty damn slow, especially given this size. Just putting 20 masts infront of each other shows diminishing effects at some point.
I can absolutely imagine some concepts like those kites supplementing some power under favorable conditions, but pure sail-driven cargo ships will remain a thing of the past, when cargo was packed in sacks and loaded manually for a two-month journy across the atlantic.
