R.I. Gen. Laws § 44-5-25.1

All houseboats being used as a principal or temporary place of residence or domicile by a person shall be taxed as personal property by the local tax assessor. For the purposes of this section, “houseboat” means a watercraft or an industrial or commercial structure on or in the waters of the state, floating or nonfloating, which is designed or remodeled as a place of habitation and is not principally used for transportation, and this definition includes platforms and waterborne hotels and restaurants; “local tax assessor”, for the purposes of this section, means the assessor for the city or town within whose harbor line the houseboat is physically situated.