[tengwar2]

This is an area I have some peripheral involvement with. For retrofitted sails on bulkers, the figure of 10% saving in fuel is the usual one mentioned rather than 20%. However given the long life of ships, there is much more interest in retrofit than in new build.

You mention container ships. I haven't seen anything explicit on these, and I think the reason is probably that they cruise much faster than bulkers and tankers, which means the potential savings from sail is smaller. I would have thought 20% optimistic even for a new-build.

[defrost]

Retro fit is clearly a preferred path for a new approach given ship life spans and size of existing global transport fleet.

My gut objection to the container approach taken above in the first link was existing container locking mechanisms for ships can struggle in severe weather to keep the boxes on the boat .. additional forces from a sail (in good weather) might well mimic the forces that break stacks in bad weather.

Your point is well taken, I might suggest that container ships could be segregated into fast and slow cargo and that might help somewhat with total fleet fuel consumption. (pure spitball notion).

[Maxion]

I'm sure there's plenty of businesses out there who'd love to advertise near zero or zero emissions transport for their goods, with the caveat that they have to plan a few more months ahead.