Tenn. Code Ann. § 67-6-345

There is exempt from the sales tax the retail sale of boats, motorboats and other vessels as defined by § 69-9-204, that are subject to registration and identification in this state pursuant to § 69-9-206, that are not registered and identified in this state, but are removed for use in another state within three (3) calendar days after physical possession of the boat, motorboat or other vessel has passed to the retail purchaser. Use of such boat, motorboat or other vessel within this state subsequent to purchase, but prior to removal from the state, does not constitute a use subject to tax.