Tapered kayak dry bag with purge valve

Thanks for your reply. The material is just the right weight for a bag that live most of it's life inside a boat hull. We reserve thicker materials for bags , such as rucksacks, that have direct and frequent abrasion from being outside. The valve , if it was at the other end, would prohibit people who wish to toll the bag down further if they only have a half load. The valve is perfectly positioned at the thin end and would be of much less use at the thick end.