Tenn. Code Ann. § 67-6-327

There is exempt from the tax imposed by this chapter repair services performed on vessels and barges of fifty (50) tons and over load displacement that are used principally in interstate or international commerce, and the parts, accessories, materials and supplies used in such repairs where the parts, accessories, materials and supplies become component parts of such vessels and barges. For purposes of this section, “repair services” includes renovations and improvements to such vessels and barges. This exemption does not apply to fuel and other petroleum products or to shop equipment and tools.