Some current gliders already have a propulsion system for fine adjustments that is also used for manouvering in port. I believe they would be too slow for any p

Some current gliders already have a propulsion system for fine adjustments that is also used for manouvering in port. I believe they would be too slow for any practical use in the merchant navy. https://en.wikipedia.org/wiki/Underwater_glider https://en.wikipedia.org/wiki/Underwater_glider