In certain wilderness survival situations you may find yourself in a situation you may have to use a local river or stream as a way to get to safety. Knowing how to build even a basic survival raft can end up meaning the difference between escape and life, or paying the ultimate price. Fortunately, a little practice and a few skills go a long way to making either a survival raft.
Collect wood logs or planks about 12 feet long, and no more than 12 inches in diameter. You will also want four smaller logs that will work as braces. See if there are any "floatable" materials such as empty plastic barrels or jugs. Also if you have an extra poncho or garbage bag, gather these up as well.
Collect the wood. In most cases you will need 10 to 15 logs, not including the lashing logs for stability. No matter what your final design, you will need to have enough wood to make a raft that is big enough to hold you and stay stable while floating, without becoming too heavy.
If available, use a cutting tool to cut hitches about a foot from the end of each log, all in a "V" shape. These will make it easier to wrap rope, vine, or twine from one log to another, making your raft more secure.
Use diagonal lashings or square lashings to tie the individual logs together. If you do not know how to tie these knots, wrap the rope or line multiple times between bordering logs and tie any type of a knot that you can make that will hold. Use duck tape if you're lucky enough to somehow have some on hand: anything to make sure the logs won't come apart on you on the water.
Take two of the smaller logs on each end of the raft, and bind them running perpendicular to the larger logs. By running one below the notches, and one above, and tying the logs together tightly you not only bind the raft closer together on both sides, but this will help the buoyancy of your raft.
Any floatable items you have should be attached to the bottom. This includes plastic barrels that are sealed, water proof ponchos or garbage bags filled with brush and completely tied off, or even large Styrofoam chunks. Anything that adds a little extra buoyancy should be added to the bottom of the raft to help resist your weight from sinking it.
Test in shallow water, and if it seems to hold, then take your chances if there are no other options. It is always a good idea to have something floatable to use as an emergency life jacket, and some type of paddle or stick to help direct you.