Find a local canvas vendor and have a set made. They can measure and make you up a set. I had a set that came with my boat and when I needed new I had them copied. I had replaced the helm seats with over the counter cushions previously and they did not hold up, pink mold came through after a couple of seasons. Had the next helm seat set made by a local canvas guy who used a higher grade vinyl. They still look great after several years of service.