I have been thinking about this for a long time, but have got only as far as http://www.theultralighthiker.com/home-made-pack-raft/ whilst others have ACTED: This girl is seriously clever (and patient): http://www.instructables.com/id/Backyard-Duct-Tape-Kayak/ here is another variation: http://www.instructables.com/id/Duct-Tape-and-PVC-Kayak/ and http://www.shelter-systems.com/kayak.html and a coracle: http://thehomesteadsurvival.com/build-coracle-person-boat-twigs/ or https://books.google.com.au/books?id=RQUETx6ha48C&pg=PA12&lpg=PA12&dq=tarp+coracle&source=bl&ots=tLN_3AyKJU&sig=2Sd_eiIyMaRThg2I3bd0Woj9jWU&hl=en&sa=X&ved=0CC4Q6AEwA2oVChMI-ObshLuRxwIVJiqmCh3xhgjC#v=onepage&q=tarp%20coracle&f=false This is probably the next step up: http://gaboats.com/ or this: http://www.instructables.com/id/Skin-on-Frame-Canoe/
