for sailing yachts that makes sense. They would use wind for most movement. While in harbor though they want the finer control that being under power allows - they don't need high speed/high power then though. They also don't spend a lot of time in this situation.

Electric tugs are now a thing to do similar for big ships.

A step before that is to have shore power to run things when in port.

In general stopping pollution near populated areas and busy ports is a bigger win and so a good place to start.

I think sailing uses mainly some other kind of energy source.

Right. And sailing container ships seem to also be coming back into vogue.

They're more like sail assisted than really "sailing" as such. Worth doing in some cases but saves maybe 10% of fuel under optimal wind conditions. The most suitable vessels will tend to be bulkers, car carriers, and tankers. Container ships are actually the hardest to add sails because they interfere with the stacks and the port cranes.

10% is a lot though.

The Neoliner Origin is a pretty interesting ship. Perhaps more ships like it will start to show up as oil gets more expensive.

https://en.wikipedia.org/wiki/Neoliner_Origin

The Neoliner Origin is a joke. It's a marketing stunt to greenwash the importation of low-volume luxury goods like cosmetics for rich customers who want to tell their friends about how they're saving the planet. The design can't scale up to transport bulk cargo in a cost effective way.

Sure but you have to start somewhere. Ive been reading about https://en.wikipedia.org/wiki/Wind-assisted_propulsion for the last 30 years so I figure every slow step forward is still a step.

Gonna work great when ocean & wind currents die/change from climate change.

It makes so much sense. The one's I've seen can be engaged in recovery mode while running your sails, so you can spin the prop and generate electricity. They only get a few hours run time fully charged, but that's plenty for port maneuvers or trip to pick up your crab pots.