That crack is in a bad place, stress and stain from the roller will make it grow. Welding is the way to go. But if thats a thin boat you will need a welder that knows what he is doing. Expensive but good. Some of those gouges don't look good either. I cracked one once across the tailgate and it always leaked, was glad to see that boat go. If you are going to use epoxy, sand the whole area you want to cover, JB Weld or the MarineTex are both good choices.