What are some good techniques to use (materials, knots, etc.) for building a raft by gathering wood in the local area? I'm talking about something to sail on still or slow moving bodies of water, not something which has to survive rapids and waterfalls!
I would say it depends on what other materials you have and how cold the water is. So if the water is cold, it's really important to stay out of it. If not, you can maybe endure having your feet hanging in, for example.
It also depends on how much time you have to build the raft. If you're in an emergency situation, don't even try a burn out canoe, it's too long.
In any case, you will need:
As for techniques, a large piece of cloth can hold a lot of branches together without using up too much rope. Also, building an outrigger can greatly improve stability without requiring too much wood.