Hydrax

The Hydrax was a human-crewed ship from the 22nd century. After venturing through a CVE, it became a permanent fixture on a planet in E-Space and was known as the Tower.

Technology
The Hydrax was equipped with a complex computer system. It had features such as scanners which could present views of a target. They were capable of seeing through surfaces like an x-ray machine. The ship had three scout ships, each with a steel bolt on top. (TV: State of Decay, PROSE: Lucifer Rising)

Crew
When the Hydrax entered E-Space, the ship's primary crew consisted of Captain Miles Sharkey, Navigational Officer Lauren MacMillan and Science Officer Anthony O'Connor. All three were turned into Vampires by the Great Vampire in preparation for the Time of Arising. (TV: State of Decay)

History
In 2127, en route from Earth to Beta Two in the Perugellis sector, the Hydrax was drawn into a CVE and through into E-space by the King Vampire. He placed it on a planet and went into hiding beneath it.

The Hydrax became a castle. It stood upright for a thousand years and rock built up around it, making it appear that it was on a hill. The detached computer system was taken by the rebels. Kalmar got it working and used its scanner function to observe the Hydrax and the surrounding area.

The Fourth Doctor fired off one of the scout ships and used its descent to impale the King Vampire's heart with its steel frontage — i.e. making the craft a huge stake. The King Vampire's death resulted in the deaths of the former crew, whose lives were dependent on him. (TV: State of Decay)

Design
The Hydrax designs were drawn up by Christine Ruscoe. The original concept showed a greater link between the ships various sections. Filming for the Hydrax's exterior took place at Mont Saint Michel. This location was chosen by Ruscoe as she believed that it looked like a spaceship.

Once this was decided upon, the period design had to be chosen. Ruscoe looked into Romanesque and medieval castles, and features from both found their way into the final design. These designs were intended to be pre-gothic to give a greater feeling of age.

Designs for the interior came from the BBC library. Ruscoe found a previously produced decorative door that she found use for as part of the throne room set.