How Does the Putt-Putt Boat Work?

How does the putt-putt boat work?

When we heat the boiler with the candle, the water droplets inside the boiler evaporate; this causes expansion. A “click” can be heard as the boiler is pushed outward.

The expanding gas forces the water out of the straws; this propels the boat forward.

A partial vacuum is left inside the boiler; this is an area of low pressure compared to the atmospheric pressure outside. A “click” can be heard as the boiler is forced inward.

The higher atmospheric pressure forces water back into the straws and the engine which restarts the cycle.

This cycle repeats many times per second.

Additional reading can be found by following the link below:

http://www.sciencetoymaker.org/boat/howBoatWorksl.html