Tom blok
The swing canoe or the dhoon
Gul streg
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The dhoon in Bangladesh
The existing law for all water-lifting devices says that output is not equal to all the power input . More than 50% is lost with some of the devices. This is not the case for the dhoon. Perhaps ten or twenty per cent is lost.
Taking a look at photo 20 we can understand how the "canoe" is pressed into the water and then lifted by means of the counterweight.
[17]
 The swinging movement.
This dhoon is very big so it needs two men. Most of the power is supplied to the dhoon on its way down in order to lift the counterweight. Then the counterweight assists the men to raise the filled dhoon.
[18]
 The dhoon in Bangladesh
The peasant buys his canoe in the marketplace, but the framework he makes himself of bamboo.
It is hard work irrigating a big field with the dhoon, so every quarter of an hour a short rest is needed. It could be calculated that 7% of the harvest goes into the stomach of the dhoon-man.
[19]

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The dhoon in Bengal
The dhoon is much used in the province of Bengal in India.
[20]