Not often seen, these helms were not originally meant to be sold. They were failures in the experiments conducted by the Arcane when attempting to build the first helms. Due to requests by various customers, the Arcane have since made them available.
The stationary helm, as the name suggests, is not capable of propelling a ship at any speeds. If the ship it is attached to enters the gravity plane of a larger object, it will fall towards the gravity plane; it cannot keep itself afloat. It only works when it creates its own gravity plane.
What it does do is allow the helmsman to rotate the ship about its axis in any manner. Although this sounds less than impressive, it has several advantages over normal helms for this purpose. First, it does it at twice the speed, and requires no rigging to do so. Second, it is much cheaper; one quarter the cost of a minor helm. Third, the level of the spellcaster in the chair is irrelevant; a first level wizard is just as effective as a twenty first level wizard. And finally, they can work with larger ships, up to 200 tons
Not surprisingly, stationary helms are rare. They aren't really even useful as a backup helm. They are most commonly seen on weapon platforms that float free around larger stations. The elves, for example, have several stationary helm equipped platforms positioned around each of their sphere bases (i.e. like Lionheart).
