Porthole

The term porthole is used in several areas. Most commonly it is used to describe a window in shipbuilding. The reason for the circular shape is the prevention of twisting (elasticity).

Use in shipbuilding

Usually a circular window is meant in sailor language. In shipping portholes serve as a waterproof side windows in the hull of ships and submarines. The often round or rounded shape makes it easy to seal and increases the compressive strength against ingress of water from outside. The function of the portholes is the same as that of windows in a building: they serve for admission of daylight or in the ventilation of the individual, situated below deck space. In addition, it allows the observation of the environment. Because of portholes are fitted in ships just above the water line.

The construction of a porthole is kept relatively simple in general: A circular sheet of glass is surrounded by a circular metal ring and also connected to a hinge with the ship's side. Normally serves the porthole not to light intake ( for example, in cargo spaces ), so it can also be manufactured only from metal. In addition, Lake stroke of metal are mounted partially in front of the portholes, which are used for example during a storm to protect against glass breakage or to darken in warships, not to attract attention or enemy fire to pull up. A seal between board and wall porthole serves as a protection against water penetration. The size is based on your usage and is between a few centimeters and a little less than one meter. Accordingly, the weight between a few and some one hundred kilograms varies. The weight resulting from the glass and the metal ring, which is usually made of bronze, copper, iron, steel or aluminum. Most often it will find bronze and copper use, as they are resistant to salt water. When planning portholes is taken to ensure that they fulfill their purposes on the one hand, on the other hand they must not impair the strength of the ship's side, and therefore the ship.

Portholes are operated from within the vessel, usually a lever for opening or closing by hand is mounted.

Another meaning comes to them for use in submarines. There they serve to monitor the environment and can not be opened normally. In addition, the portholes submarines to enhance the resistance against the water pressure from the outside are usually concave. This causes them to be pressed against the frame of the porthole. On the inside they are usually not spherically, this reduces the one hand, the field of view to the outside, on the other hand be glass voltages that may occur due to the curvature decreased. Depending on the depth at which the submarine is to be used, the portholes are thick up to several centimeters.

Use in space

In the same form as in ships such windows are also used in space travel, for instance on the International Space Station. They are used to being able to see outside.

They are usually made of quartz glass, since the glass has to withstand a temperature difference of several hundred degrees Celsius without cracking under the strain. The frame is made ​​of titanium, and then coated with enamel.

The Apollo capsules a porthole was mounted in the rear, which made ​​it possible to get in and out at the beginning and end of each flight.

Use in washing machines

In another use of the term is used in connection with front loader washing machines in the household sector, there is a porthole as a loading hatch. The glass met here only a useful but not absolutely necessary in today's function, as the washing is usually automated. It allows the washing process to observe from the outside without having to interrupt him.

The porthole here comes the reverse meaning as in shipping to: It is used to seal the washing machine to the outside and to prevent leakage of water. The production method is similar to that in shipbuilding, also here is the metal frame and the bullseye has a lever to open and close it.

Use in architecture

In architecture, called porthole, or more frequently ox-eye, round or oval window, as they were particularly common in the Baroque.

Other uses

On the English darts darts called the Bull 's Eye (short: the Bull), the center of the target. The translation of Bull 's Eye as a porthole is a typical false friend.

In the past, also referred to as a fried egg porthole, porthole or bull's-eye.