On woven acrylic canvas, yes, but only for mildew or a stain that will not lift with soap. Brush the dry fabric first, then mix 1 cup of bleach and ¼ cup of mild soap per gallon of cold fresh water. Let it soak in for up to 15 minutes, blot from the outside of the stain inward, and rinse until no soap is left. Air dry completely. Bleach discolors whatever it runs onto, so cover seats, decking and plants underneath. Never soak bleach on marine vinyl or clear vinyl, and keep it weak and off the seams on drop screens and mesh. Every deep clean with bleach wears the water-repellent finish, so check whether water still beads afterwards.