All vessels need to be equipped with main steering gear and auxiliary steering gear (often called emergency steering). The steering gear ar-rangement, function and capacity of steering gear, and strength of steering gear components are subjects to design approval. There are also strict requirements for material, workshop, and shipboard testing. //DNV-RU-SHIP Pt.4 Ch.10 Sec.2-4 and 8

Main and auxiliary steering gear power unit shall restart automatically when power is restored after a power failure and be capable of being brought into operation from the navigating bridge. The power supply shall be arranged with redundancy and means of main and emergency power supply. Typically, each power unit is provided with separate circuit fed from the main switchboard. Additional emergency supply is arranged for one of the power units from emergency switchboard or another alternative independent power source.
Alternatively, one of the power units can be fed only from the emergency switchboard. The emergency supply shall have capacity for minimum 10 minutes of continuous operation. For bigger vessels alternative power supply shall be provided automatically within 45 seconds and have capacity for 30 minutes continuous operation. //DNV-RU-SHIP Pt.4 Ch.10 Sec.5
The main steering gear shall have capacity to turn the rudder from 35 degrees on one side to 30 degrees on the other side within 28 seconds at maximum ahead service speed. Minimum required turning angle is 35⁰ both sides. For ram type steering gear this is normally also the maximum permissible turning angle.
The capacity for emergency steering gear shall be enough to turn rudder from 15⁰ on one side to 15⁰ on other side within 60 seconds at minimum 7 knots (or half of the maximum ahead service speed, whichever is greater). //DNV-RU-SHIP Pt.4 Ch.10 Sec.2

Last modified: Thursday, 4 May 2023, 4:13 PM