Remove the seats from the boat and use them to gauge how much fabric you will need for the new covers. Turn the seats over and remove the existing fabric by taking out the staples on the bottom. A flathead screwdriver is great for removing staples.
Lay the new fabric face down on a flat surface, then lay the old fabric face down on top of it. Trace around the outside of the old fabric with a pencil or marker, then use scissors to cut out the shape. Electric scissors work very well on thicker fabrics, but if you have a sharp pair of manual scissors, they will work as well.
After the pieces of fabric for each seat have been cut out, lay each one out on the table face down. Place the foam face down on top and then the wood base.
Begin pulling the fabric up and stapling it to the wood base. Place a staple at four equal points on the wood base, then pull and staple the fabric all around the wood base.