Hi there,
To obtain residency through Yacht ownership, you must be able to provide a signed contract of mooring with one of the recognised Montenegrin Marinas. There is not specific definition of a yacht, but I guess a rib would not apply for example... Marinas like Porto Montenegro in Tivat, do not have berths for smaller yachts (under 25m if I recall well), so if you wanted your yacht to be there, you would need a larger yacht. It can be a challenge to find berths in other marinas also...
Most °µÍø½ûÇøs obtain residency either through a work contract, or property ownership (you can be 2 owners for 1 property).