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Portholes are circular windows which are predominantly used as lateral windows on the side of a boat in the shipping industry (also for submarines), in order to let light or air in. The round shape serves for the improvement of characteristics such as waterproofing and pressure resistance against unwanted water exposure. Portholes are not only used in the shipping industry.

More fields of application of portholes can be found in the

1. Aircraft Industry

Whereas only rectangular windows were used at the beginning of aviation, the development has developed since the 1950s to round or oval portholes. There are two main reasons for this. Due to a higher flight altitude, on one hand turbulence in a lower atmosphere could be avoided. On the other hand, air density at altitudes is significantly lower, thus leading to reduced air resistance and as such lower fuel costs. This is why portholes were further developed for higher altitudes and here the shape offers much better protection, in order to compensate the pressure difference between the inner and outer space.

2. Aerospace

In aerospace, portholes also serve as windows. At the international space station for example, the porthole is used. Its shape serves again to improve important characteristics. In this case, this especially concerns the endurance toward extremely large temperature differences. This is why in aerospace other materials are used for the portholes, in order to make them endure extreme conditions. In part, portholes have also been used as “doors” to get in or out.

3. Washing Machines

In washing machines, the porthole has a long-lasting tradition. First and foremost it serves here as a hatch, but also as a window in order to be able to observe the washing procedure from the outside. Since today’s washing machines work automatically, this function is not really necessary anymore. In the washing machine, the porthole actually has a converse function than in the shipping industry. It protects the washing machine from the outside and should prevent water from leaking out.

4. Architecture

A lot of modern buildings use portholes nowadays. In these cases, the use is for the design and not to comply with special requirements, such as it is the case in other fields of application.

Portholes have versatile fields of application. Only the most important fields were mentioned previously. Of course, there are plenty more areas which can be discovered, where portholes can be used as object of purpose or design. In the automotive industry for example, in the 1950s, a small porthole was built into the hardtop of the Ford Thunderbird.

Where the first portholes came from

The first portholes were also used in seafaring, however they did not serve as light or air windows. According to the "Naval History and Heritage Command", the first portholes originated in the 14th century during the reign of Henry VI. The portholes served as windows, in order to be able to take out the cannons faster during battle. When not fighting, the portholes could simple be covered. During the course of time, real portholes have established themselves in seafaring due to their capacity as a result of their shape.

What materials portholes are made of

The classic portholes consist of a metal frame with a window. The window is made of glass or plastic as a rule. The metal frames are often composed of bronze, copper, iron, steel, aluminium or brass. As a rule, there is also a lever to open or close the window. Depending on the size of the porthole, they can attain considerable weight. For their use in the aircraft industry, in aerospace or under water, the requirements on portholes are essentially higher, reason why other materials are used here. Depending on the requirements, the curves and shapes (round, oval) of the portholes are different.

You want more information about the installation of the portholes. Watch our video on Youtube: