Thursday, 21 June 2012

Powering a Boat using the Marangoni Effect

Two things Finns love.  Alcohol and boating.  Combining them as Robin Ras did at Aalto University makes absolute magic.  This scientist made a boat out of a substance called Aerogel run for nearly an hour.  Watch the video then see how it works.

This will not work for a freighter, or even a canoe unfortunately.  The gel is still really expensive to produce and not really durable enough.  It does make scientists think about boat propulsion and may be used to reduce the drag on large ships.  Maybe in the future we will go further and have interesting crafts without using any fuel but propelled only by the physical chemical properties of water and a sip of your beer (too bad alcohol in Finland has such a high tax rate!)

Watch the video:

How does this work?

The craft doesn't have an equally tiny motor pushing it through the water. Instead, as the ethanol on the rear of the craft vaporizes and passes through the aerogel's nanocellulose membrane, it lowers the surface tension of the water around the boat.  When the surface tension is lowered around the boat less friction is working against it.  But as the front of the boat passes and the surface tension of the water behind it increases again, it tends to naturally push it along.  In summary the boat can travel 74 meters for 54 minutes on only 25 microliters of ethanol.  This was reported in New Scientist.

Man Mimicking Nature

Again mankind is only mimicking what nature already does really well.  Water striders excrete surfactants to help them move in water better.