Effect of refraction and field of view of acrylic viewports of shallow water spherical pressure hull

Abstract

A shallow water spherical hull for manned submersible has been designed and developed by National Institute of Ocean Technology, India. During the design phase, a detailed study was carried out concerning the conical acrylic viewports, to understand the limit of aperture, field of view through viewports, field of view of seafloor, and reflection. It is also important to understand the effect of refraction due to acrylic and sea water, which is significant for making engineering judgements while collecting samples from the seabed. This study recommends having larger diameter viewports and larger angles between the primary and secondary viewports. A limitation would be that increasing the diameter of the viewport would increase the size of the viewport flange. Highlights The layout of the observation windows, field of view, field of view of the sea floor, and refraction effects are studied Effect of refraction due to acrylic and sea water, which is significant for making engineering judgements while collecting samples from the seabed The distortion depends on the viewing angle, thickness of the viewport window, and object distance inside the sea water Minimum overlapping regions in the fields of view of viewports need to be maintained so that two crews can see the objects together which fall in the common field of view