Lay two 70-inch boards flat, parallel and 13 inches apart. Set three 68-inch boards on top of them so they are at right angles. Space the 68-inch boards 25 inches apart. The ends of the 68-inch boards will be 24 inches away from the sides of the 70-inch boards, and the two outside boards will be 5 1/2 inches away from the ends of the 70-inch boards. Screw the 68-inch boards to the 70-inch boards using four screws for each board. Repeat this step with the last pair of 70-inch boards and the last three 64-inch boards. These are the ends to your boat rack carrier.
Position the ends upright so the 70-inch boards are vertical and between the 64-inch boards. The outside edges of the 70-inch boards should be 96 inches apart. Screw the 96-inch boards to the 70-inch boards so each 96-inch board is resting on a pair of 68-inch boards. Use four screws for each board. There will be three 96-inch boards on each side of the rack and their ends will be flush with the 70-inch boards.
Screw a swivel wheel to the bottom of each 70-inch board. Use the screws provided.
Set your kayaks or canoes on top of the 68-inch boards. Use two bungee cords for each boat and wrap them around the 70-inch boards to keep the boats on the rack when you move it from one location to another.