explain how a concrete boat would float?

Answer 1

Just like a steel one does: it is shaped in such a way as to enclose air, and ends up displacing more than its own weight.

Answer 2

Any time the volume of the vessel is more than the volume of water displaced it will float by creating a 'lighter than water' container. This can be done with any material that can be shaped into a hollow container, and concrete is no exception.

But the weight of the water displaced is exactly the same as the weight of the vessel.

Ask yourself, why did old sailing ships sink if they were made of wood? Because the materials used included heavy ballast stones in the bottom to keep the ship upright and stable under sail. This made the vessel sinkable, and the only thing that kept them afloat was keeping the water out. If the interior of the wooden ship filled with water, down it went.

Answer 3

Floating depends upon displacement. If the concrete displaces its weight in the water and is still above the surface, you have float.

I watched a guy build a concrete boat when I was young.

Answer 4

All it has to do is displace more water (weight-wise) than what it weighs.

Let's say the boat weighs a ton. Water weighs about 64 pounds per cubic ft. 2000/64 = 31.25, so the boat would only need to displace 32 cubic ft or more of water for it to float

Answer 5

The exact same way that a ship made of steel can float. Steel is more dense than concrete. Do you understand what makes anything float?

Answer 6

it is not all about density it is also about surface tension, and buoyancy the air in the boat helps it keep a float