How to fold a paper boat

The folding method of the paper boat is as follows:

1. Fold the rectangular paper twice.

2. Expand to the first folded state, and then fold the left and right corners to the center line respectively.

3. Fold the first layer of the bottom rectangular part upwards, then turn the paper upside down and fold the redundant corners at both sides downwards; The second layer is folded in the same way.

4. Open the paper to both sides and flatten it.

5. Fold the two corners of the opening upwards respectively, and then repeat the fourth step.

6. Grab two corners and pull to both sides, and a simple origami boat will be folded.

Ship design considerations-fluid dynamics;

When a ship sails in water, its leading edge will be resisted by water, which can be divided into many components, mainly the resistance of water acting on the hull and wave resistance. If the resistance decreases, the speed will naturally increase, and it is necessary to reduce the wetted surface. The hull without water should also be changed into a shape with smaller amplitude of water waves.

In order to achieve this goal, high-speed ships are generally slender and have little or no attachments. If the parasitic organisms and algae on the hull are cleaned regularly, the resistance of the ship can also be reduced, and the antifouling paint can also reduce the organisms on the hull. Advanced design such as spherical bow can also reduce wave resistance.

A simple way to consider wave resistance is to look at the relationship between the hull and the waves it produces. If the ship's speed is slower than the ship's wave propagation speed, the ship's wave will dissipate quickly on both sides of the ship. However, if the speed of the ship is equal to the speed of ship wave propagation, the speed of ship wave energy increase will be faster than the speed of energy dissipation, so the amplitude of ship wave will increase.