Keeping your kit dry in difficult conditions has all manner of dry bags and sealed rigid boxes etc. Some it would seem are better than others. Another alternative would be the Polycarbonate Nalgenes that no one wants to drink from anymore due to the BPA. They are very lightweight, tough and waterproof.

BTW whats the make of the Dry bag which failed. It looks like one of those lightweight eVent compression sacks. One to avoid it would seem. Gul and Musto waterproof dry bags might be the way to go for your application.

http://www.speedsails.co.uk/C~Waterproof_Dry_Bags__4703.html