As per SOLAS, Chapter ll.-l construction
A rudder stock of over 120 mm diameter in way of the tiller, excluding strengthening for navigation in ice; and so designed that they will not be damaged at maximum astern speed; however, this design requirement need not be proved by trials at maximum astern speed and maximum rudder angle.
The auxiliary steering gear shall be:
- Of adequate strength and capable of steering the ship at navigable Speed and of being brought speedily into action in an Emergency;
- Capable of putting the rudder over from 15 degree on one side to 15 degree On the other side in not more than 60 seconds with the ship at its Deepest seagoing draught and running ahead at one-half of the Maximum ahead service speed or 7 knots, whichever is the Greater; and
- Operated by power where necessary to meet the requirements of Paragraph 4.2 and in any case when the administration requires A rudder stock of over 230 mm diameter in way of the tiller, Excluding strengthening for navigation in ice.
Main and auxiliary steering gear power units shall be: arranged to restart automatically when power is restored after a power failure; and be capable of being brought into operation from a position on the navigation bridge. In the event of a power failure to any one of the steering gear powers units, an audible and visual alarm shall be given on the Navigation Bridge.
Where the main, steering gear comprises two or more identical power units, an auxiliary steering gear need not be fitted, provided that: