How To Make A Raft

The first river rafting adventure involved four of us. I told my friends to be ready for an adventure-disaster, sure to get them wet and cold. Three took the bait. We took only a hatchet, a small saw, snacks, water, and whatever scraps of rope we could find - all in one small backpack.

We parked at a bridge and hiked up river until we were a few miles from the car. We would build a raft, using dead trees and our scraps of rope. Then we would then get on it and float back to the car. That is sort of what we did - but that is another story. This is a how-to guide.

How To Make A Raft

An axe or hatchet can help, but the easiest way to cut your trees will be with a saw. For some reason, the toolbox-sized "short-cut" saws work better than the longer ones, and are easier to carry in a day pack. Other than this tool, all you really need is about 100 feet of rope or heavy twine. This can be scraps, or you can buy whatever they have at the dollar store.

Once you are out in the woods, you want to scout for an area that is near the river and has a lot of dead trees. Apart from the environmental concerns, live trees just don't float well. Look for trees that are no more than ten or twelve inches in diameter, or you'll wear yourself out trying to cut them.

What kind of trees should you use? You may not have much of a choice. If you do have a choice, look for those with the lightest wood and those that are easiest to cut - try for both if you can. Even dead and dry, maples are likely to weigh 45 pounds per cubic foot - meaning they won't provide much lift. They will also be one of the most difficult to cut. A white cedar at 30 pounds per cubic foot is a better choice.

Cedar is not all that easy to cut either, however. For ease of cutting, and light weight, my favorite is slightly dry-rotted poplar or cottonwood trees. Some older specimens are like Styrofoam when you cut them, and probably weigh about 25 pounds per cubic foot. The only problem with these is that they will waterlog more quickly than other woods, so they are best for one-day trips.

Cut the trees down and cut them into usable lengths. Shorter logs mean more cuts. For this reason and for maneuverability, it may be better to have a longer, narrower raft. I like to aim for logs about ten to twelve feet in length.

How many logs? That depends on the weight of the passengers and gear, and the wood used. Water weighs 64 pounds per cubic foot. Subtract from that the weight of the wood you are using, and you get your lifting capacity. In other words, if the trees you are using weigh about 39 pounds per cubic foot, they will carry about 25 pounds per cubic foot (64 minus 39).

Suppose you have 600 pounds of people and gear, and wood that has a lifting capacity of 25 pounds per cubic foot. In that case 24 cubic feet of wood will float you (600 divided by 25) - but try for double that or you'll be standing in the water as you "float." You are aiming for 48 cubic feet then.

The volume of a cylindrical object is pi times the radius squared, times the length. Pi is roughly 3.14, and there are 1728 cubic inches in a cubic foot. Now suppose your logs are about 12-feet long and 8 inches in diameter. Let's see... the radius is 4 inches. Square that (4 x 4) and you get 16. Multiply that times 3.14 and you have 50.24 times 144 inches of length for a total of 7,234 cubic inches. Divide that by 1728 and you get 4.19 cubic feet per log.

Okay, you need about 12 such logs to get your 48 cubic feet of wood. Is there an easier way? You bet. Just get a lot more logs together than you think you'll need.

It is easiest to assemble the raft in the water - a lesson learned by hard experience. Cut four or five long skinny poles. Two will be tied to the logs on top, at both ends, and one will be tied on top diagonally (important - another lesson learned the hard way). The other one or two will be the rafting poles you and your friend use to guide the raft.

If you have a cooler, set it in the middle as a seat, to keep any non-pilots out of the way. You can also use an old stump or log for this. Those in control will have to remain standing for the duration of the trip, as you will learn from experience. This is how you make a raft and float down a river.