There was a warm, quiet evening

Walking along the seashore, I looked at the sunset and fishing boats, which in large numbers were in the coastal waters.

I must tell you about the strange boats of the Vietnamese. These boats are like big basins. The round form of these "basins" is not accidental.

The round flat-bottomed boat has the maximum transverse stability, it doesn't turn over even with a big wave. And if an ordinary boat should always be kept nosed across the wave, then this is not required.

It is most easily managed in a confined space. Turning left and right on it a skilled Vietnamese can be much quicker than on the usual in our understanding of the boat.

The circular shape of the boat makes it safer and more convenient for such coastal exits to the sea.
Of course, if you want to go to the open sea or make a big transition such a boat is not suitable, but in a coastal wave - this is an ideal solution.

But there's a story (I would say a legend) about the round boat shape.

The French decided to tax the fishing part of the population of the country on the territory of the colonial Vietnam then. All boat owners must pay a fee.
Documented what is a boat, so that you can properly collect taxes. Naturally, the definition of the boat took into account an ordinary boat with a keel.
A cunning Vietnamese slaves began to weave instead of normal boats large baskets in which they caught fish.
Tax inspectors did not find boats for fishermen and could not tax the baskets.

But this, of course, is just a legend.