To keep a 5-gallon bucket from scratching the cockpit deck in rough seas, clean the bottom of it really well, dry it thoroughly, then rough up the surface with some heavy grit sandpaper. Take a can of expansion foam (such as Great Stuff) and coat the bottom of the bucket - I start in the center of the bucket and work my way to the edge in a circular motion. After the expansion foam dries, take a hand saw and saw the excess foam all the way around the bucket. Finally, turn the bucket on its side and saw the foam, parallel to the bucket's bottom surface, approximately 1/2" off the bottom of the bucket. Make sure the saw maintains an even cut, so the bucket will sit flat on the surface. You now have a bucket with a soft, nonskid bottom surface that will last for years.