The Chinese Fishing Nets

I have always heard about the Chinese fishing nets at Cochin and always wondered what is so special about those nets. During my visit to Cochin i got chance to see those net in operation along the seashore.

They are called as Chinese nets because they are believed to be first erected here by the Chinese people who came here for business...

In my opinion this must be the first practical application of the Bell Crank Lever. With a nice use of the principle of balance of Moments about a hinge...

At one end of the lever you have got the net and on the other end of the lever there are people who with ropes raise or lower the lever thus making the net go inside or come out of the water.
The moment exerted by the net and its structure at one end is balanced by hanging stones to the other end of the lever.

When the net is to be immersed in water, a person climbs over to the "net" lever thus tipping the balance to the "net" side. Slowly the net goes inside water. They wait for some time and after that they will pull the ropes tied to the "rope" lever. Thus applying moment that tips the balance to the "rope" side and thus the net is out of water.

The fishermen then go and collect whatever fishes are caught in the net.

These nets rise two opposite thoughts in my mind...

first is that how lazy the people must be who used these nets... because since these nets are fixed in one place you can not go into deep water for fishing and must be satisfied with whatever you get. may be they were initially intended for use in the small river or say backwaters in this case...

On the other hand they also represent an amazing application of a simple principle. That is too completely wooden. it is really fun to see the man going up the "net" lever and the net going slowly under water... and then the pulling out operation wherein the effort applied reduce gradually as the moment applied by the weight of the hanging stones increases gradually as the "rope" lever is pulled down...

the most amazing scene is when these net are used in conjunction with a lamp during night. The lamp is hanged to the frame such that it remains just above the water when the net is fully under water.

The fishes and crabs etc are attracted to the light and thus caught in the net...