§ 58.25-5 General. ( a ) The following definitions apply to this subpart: *Ancillary steering equipment* means steering equipment, other than the required control systems and power actuating systems, that either is not required, such as automatic pilot or non-followup control from the pilothouse, or is necessary to perform a specific required function, such as the automatic detection and isolation of a defective section of a tanker's hydraulic steering gear.
*Auxiliary steering gear* means the equipment, other than any part of the main steering gear, necessary to steer the vessel in case of failure of the main steering gear, not including a tiller, quadrant, or other component serving the same purpose.
*Control system* means the equipment by which orders for rudder movement are transmitted from the pilothouse to the steering-gear power units. A control system for steering gear includes, but is not limited to, one or more— ( i ) Transmitters;
( ii ) Receivers;
( iii ) Feedback devices;
( iv ) Hydraulic servo-control pumps, with associated motors and motor controllers;
( v ) Differential units, hunting gear, and similar devices;
( vi ) All gearing, piping, shafting, cables, circuitry, and ancillary devices for controlling the output of power units; and
( vii ) Means of bringing steering-gear power units into operation.
*Fast-acting valve,* as used in this subpart, means a ball, plug, spool, or similar valve with a handle connected for quick manual operation.
*Followup control* means closed-loop (feedback) control that relates the position of the helm to a specific rudder angle by transmitting the helm-angle order to the power actuating system and, by means of feedback, automatically stopping the rudder when the angle selected by the helm is reached.
*Main steering gear* means the machinery, including power actuating systems, and the means of applying torque to the rudder stock, such as a tiller or quadrant, necessary for moving the rudder to steer the vessel in normal service.
*Maximum ahead service speed* means the greatest speed that a vessel is designed to maintain in service at sea at the deepest loadline draft.
*Maximum astern speed* means the speed that it is estimated the vessel can attain at the maximum designed power astern at the deepest loadline draft.
*Power actuating system* means the hydraulic equipment for applying torque to the rudder stock. It includes, but is not limited to— ( i ) Rudder actuators;
( ii ) Steering-gear power units; and
( iii ) Pipes, valves, fittings, linkages, and cables for transmitting power from the power unit or units to the rudder actuator or actuators.
*Speedily regained,* as used in this subpart, refers to the time it takes one qualified crewmember, after arriving in the steering-gear compartment, and without the use of tools, to respond to a failure of the steering gear and take the necessary corrective action.
*Steering capability* means steering equivalent to that required of auxiliary steering gear by § 58.25-10(c)(2).
*Steering gear* means the machinery, including power actuating systems, control systems, and ancillary equipment, necessary for moving the rudder to steer the vessel.
*Steering-gear power unit* means: ( i ) In the case of electric steering gear, an electric motor and its associated electrical equipment, including motor controller, disconnect switch, and feeder circuit.
( ii ) In the case of an electro-hydraulic steering gear, an electric motor, connected pump, and associated electrical equipment such as the motor controller, disconnect switch, and feeder circuit.
( iii ) In the case of hydraulic steering gear, the pump and its prime mover.
*Tank vessel,* as used in this subpart, means a self-propelled vessel, including a chemical tanker or a gas carrier, defined either as a tanker by 46 U.S.C. 2101(38) or as a tank vessel by 46 U.S.C. 2101(39).
( b ) Unless it otherwise complies with this subpart, each self-propelled vessel must be provided with a main steering gear and an auxiliary steering gear. These gear must be arranged so that— ( 1 ) The failure of one will not render the other inoperative; and
( 2 ) Transfer from the main to the auxiliary can be effected quickly.
( c ) Each substantial replacement of steering-gear components or reconfiguration of steering-gear arrangements on an existing vessel must comply with the requirements of this subpart for new installations to the satisfaction of the cognizant Officer in Charge, Marine Inspection.
( d ) Each non-pressure-containing steering-gear component and each rudder stock must be of sound and reliable construction, meet the minimum material requirements of § 58.25-75, and be designed to standards at least equal to those established by the ABS Marine Vessel Rules (incorporated by reference, see § 58.03-1).
( e ) The suitability of any essential steering-gear component not duplicated must be specifically approved by the Commanding Officer, Marine Safety Center. Where a steering-gear component is shared by— ( 1 ) A control system (e.g., a control-system transfer switch located in the steering-gear compartment);
( 2 ) The main and auxiliary steering gear (e.g., an isolation valve); or
( 3 ) A power actuating system and its control system (e.g., a directional control valve)—the requirements for both systems apply, to provide the safest and most reliable arrangement.
( f ) Steering gear must be separate and independent of all other shipboard systems, except— ( 1 ) Electrical switchboards from which they are powered;
( 2 ) Automatic pilots and similar navigational equipment; and
( 3 ) Propulsion machinery for an integrated system of propulsion and steering.
( g ) Except on a vessel with an integrated system of propulsion and steering, no thruster may count as part of a vessel's required steering capability.
( h ) Except for a tank vessel subject to § 58.25-85(e), each oceangoing vessel required to have power-operated steering gear must be provided with arrangements for steadying the rudder both in an emergency and during a shift from one steering gear to another. On hydraulic steering gear, a suitable arrangement of stop valves in the main piping is an acceptable means of steadying the rudder.
( i ) General arrangement plans for the main and auxiliary steering gear and their piping must be submitted for approval in accordance with subpart 50.20 of this subchapter.
[CGD 83-043, 60 FR 24776, May 10, 1995, as amended by USCG-2003-16630, 73 FR 65187, Oct. 31, 2008; USCG-2020-0634, 89 FR 50173, June 12, 2024]