Most states do not require registration on a "water vessel" that is 16 to 18ft or shorter in length AND has no powered source of drive, that require human oars sticks, pedals or some type of human intervention to move the boat. Other states require a license for anything that hits the water more than 8ft long, powered or not.
I see this online, vessels NOT requiring registration in Texas: All (non-motorized) canoes, kayaks, punts, rowboats, or rubber rafts (regardless of length) when paddled, poled, or oared.
Just to be safe I would suggest checking with the license and registration offices just to be sure, and be specific and exact with your wording.