The ship port hole or also known as the ship side scuttle by some is most likely round in shape, port holes are found on an array of different craft besides marine vessels but they seem to be more obvious on marine vessels. Space craft, air craft, armed vehicles among some vehicles all have the port hole, which leads to raise the most asked question concerning the port hole! Why are they always round in shape?
The design was adopted during the initial ship building years when the industrial revolution was taking place, before then sailors below deck faced problems due to congestion and a dire solution had to be found to give the sailors below deck better conditions to work in. During the industrial revolution steel and glass began replacing wood in ship construction. Steel offered strength thus sparking the creation of larger vessels while glass offers transparency.
It was soon adapted in to ship building as pioneering ship builders as well as captains understood the situations that ship personnel below deck had to endure while on long voyages. With this clear glass had to adopted and used onboard marine vessels lower decks where the personnel mostly worked and slept. Extensive calculations had to made, that maintained the ships integrity since glass is brittle and can brake under pressure during bad weather.
The engineers realized that glass grew weaker when more surface area was exposed the presser and actually had the opposite effect when the glass was made smaller. This was a first development to the adoption of glass ship port holes in the pioneering ships but soon a major problem was discovered when ships were our at sea. The glass portholes were strong enough to withstand the pressure exerted on the by the waves but the glass ceiling agent was not strong enough and would buckle under pressure.
In depth investigation in to this problem discovered that sharp edged glass was affected more and that lead to the discovery that the sealing agent was weakened when it was used on a 90° angles glass or any sharp edges. This was soon solved by the introduction of rounded edges that would provide a firmer grip round the whole glasses edges with no weakened gaps left out.
This was the initial advantage that was discovered
but as time passed other important developments and discoveries were made associated to the round glass, as port holes began being adopted in to the air craft industry, air presser was beginning to play havoc in the sky since the glass would shatter under intense atmospheric pressure and developers had to improvise new designs the would maintain the transparency of the glass as well and improved the strength.
Initially the shape of the glass played a major role of strengthening the glass. Convex shaped glass would strengthen the glass tenfold way beyond the requirements of aviation but with the introduction of space travel a glass ship port hole had to endure fare higher vacuum pressers in space. This lead to the development on laminated re-enforced glass which is still being developed for space craft including satellites and cameras onboard them since they are require to withstand the vacuum pressers in space.