Why Does Wood Float?

Wooden boats, rafts, canoes, and wooden toy boats, why do these float? Is it because of a special property in wood that makes it float? Something as heavy as a log can also float in water! The secret to wood’s floating powers will be revealed in this short guide about wood and its properties.

Wood’s floating capabilities revealed

Wood like wooden plants and logs floats because these are naturally lightweight and these float in a large body of water. Let the same plank float in your bathtub then you will find that these will sink.

When something a log of wood is put into water, the weight of the log pushes down on the water and the water naturally moves aside to make room for the log. This is similar to your tub; water moves out and around to make room for you when you step in. And when there is enough water to push back up against the object with similar force as the object pushes down, then this object will surely float.

Consider a piece of wood that is lightweight for its size will float in a huge body of water, like the ocean or in a river. But when you place this same piece of wood in a tub or in a pool, it will sink or won’t float at all.

Wood floats but stone sinks

Here is another age-old question. You may have seen people carrying wood through rivers. These people cut the wood and put the logs into the river. The current in the river simply takes the log to wherever it needs to be. These logs naturally float in water and move towards the direction the river flows. The speedy current of the river pushes the big logs forward just like it will push a canoe or a small raft towards the end of the river.

Logs taken to sawmills are usually allowed to float in rivers. Some of these logs are thousands of kilograms while we may weigh only a few kilograms. Yet when we jump in the water, we tend to sink. Unless we try to relax and float, we won’t be able to do so. The heavier wooden logs float despite their gigantic sizes.

Throw a small stone (weighing about less than a kilogram) into the water. It will obviously sink.

Large wooden logs float while very tiny stones will sink.

Wood float because it’s less dense.

Most wood species are less dense than water and that makes wood incapable of pushing away water and go beneath. Wood is composed of fibers and there are voids in between these wooden fibers. Objects such as coins, stones, and nails are denser than water, therefore, these will sink as these are placed in water.

Buoyancy and buoyant force

Another reason why wood can float as well as big ships can float is buoyancy. If you have tried swimming deep down the water to check the corals or just the deeper side of a swimming pool then you may have found it very difficult right? This is extremely difficult compared to just swimming upward or forward.

This is because water pushes every object that falls into it upward. When you want to go deeper, the force is higher. The upward force on objects by fluids including water is known as buoyancy or Buoyant force. This is the same force that keeps large sailing ships afloat. It is the same principle that keeps large logs a float as well.

The lightest wood

Balsa is one of the lightest woods. Its lightweight properties are not tested in water though, it is tested on air. It is the foremost material to build model airplanes and no doubt that it is among the easiest to use. You can find model airplane kits that use balsa wood. This wood is light, easy to use and less dense. You can also purchase balsa wood sheets and lumber to be used for your projects from suppliers.


Wood floats because it is affected by buoyant force. Wood is also filled with air and water cavities and these allow the wood to float easily as well. Among the lightest woods is balsa and is not tested in water. It is so light that it is used for building model airplanes.

  • December 29, 2018
  • DIY
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