ALIA Expedition
Report on the Submersibles Pisces IV/V

Of all the tools that oceanographers use to examine the ocean and the many objects of interest within it, only the submersible actually allows them to look at the ocean. The R/V, or Research Vessel, Kaimikai O Kanaloa has two submersibles, Pisces IV and Pisces V, which they use to lower themselves into the ocean’s depths. Though both were built in the 1970’s, they have been since upgraded with all new sensors and control equipment, allowing them to very effectively study the ocean’s floor. The Hull or main structure of the submersible is a steel sphere, this is the most sound shape for underwater objects, since the immense pressure is distributed equally around the object, giving it the power of an arch, but in every direction. The Pisces can comfortably descend to 2000m, which allow scientists to comfortably examine places like the crater floor at Vailulu’u, which lies approximately a kilometer beneath the ocean. The pressures at such depths are truly great, they can, and always do, crush styrofoam cups that crew members attach to the outside of the submersible. It is impressive to see the forces of the ocean turn a large cup into a thimble.

Such pressures can easily make life difficult should the ocean find a path into the submersible, to avoid such a disaster all elements of the submersible are carefully designed. The edges of the hatch are shaped like a cone, so the external pressure of the ocean actually forces the hatch to have a tighter and tighter seal with the submersible. Likewise, a simple hinge on the hatch would not be acceptable, if you examine a door as it closes you will notice that it approaches at an angle, and then has a gap between it and the frame. Since a gap around the edge of a submersible’s hatch would be clearly disastrous, imagine, or try, opening the door and filling the gap that existed when it was closed. Because the door has a thickness, and it is pivoting around a single point, the door will jam and now fail to close (hopefully you didn’t try this experiment with some sort of permanent addition to the doorframe). It is for this reason, that the submersible has a more complicated hinge system, allowing it to close by traveling straight into its frame. On top of this, there is a ‘classic’ spinning hatch wheel that tightens down the hatch and prevents it from being bumped out of place, or accidentally opened from the inside or out. 

One of the most interesting controls on the submersible is the controller for the robotic arm on the outside of the sub. It is controlled by a little mock-up of the arm, which acts like a complicated joystick. Each joint on the control stick, has a little device in it which measures the angle in which it is positioned, this is then interpreted by a computer, and the actual arm on the outside of the sub moves accordingly. Even the rate of the movement is replicated, within some safety limits, so that an experienced user feels as though the arm is an extension of them.

Pisces IV and V are a sophisticated way of delivering people to the depths of the ocean, and in many ways, in terms of alien view, exposure to harsh elements, and excitement resemble manned missions into space.