46 CFR 143.585: Propulsion, steering, and related controls on towing vessels
Last reviewed: October 14, 2026
This section sets general requirements for propulsion, steering, and related controls. It requires an alternate means of control, communication, a means to stop engines and steering motors, alarms, and backup power. It also requires the control system to be designed to handle a single failure.
What it says
There must be an alternate means to control the propulsion and steering system, and it must be independent of the primary control required by § 143.225.
46 CFR 143.585(a)“There must be an alternate means to control the propulsion and steering system which must:”
The alternate control must be readily accessible and suitable for prolonged operation.
46 CFR 143.585(a)(3)“Be readily accessible and suitable for prolonged operation.”
There must be a means to stop each propulsion engine and steering motor from each operating station.
46 CFR 143.585(c)“There must be a means to stop each propulsion engine and steering motor from each operating station.”
The propulsion control system required by § 143.225 must be designed so that, if any single component fails, propeller speed and direction of thrust are maintained or reduced to zero.
46 CFR 143.585(e)“propeller speed and direction of thrust are maintained or reduced to zero.”
An audible and visual alarm must actuate at each operating station when the propulsion control system fails, and in the other cases listed in this paragraph.
46 CFR 143.585(g)“An audible and visual alarm must actuate at each operating station when:”
The two sources of electricity required by § 143.555(a)(3) and (b)(8) must be able to power the loads needed to maintain propulsion, steering, and related controls for not less than 3 hours.
46 CFR 143.585(j)“must be capable of powering electrical loads needed to maintain propulsion, steering, and related controls for not less than 3 hours.”
The second source of supply required by § 143.555(a)(3) must start automatically to help restore or maintain power when the main power source fails.
46 CFR 143.585(k)“must automatically start to help restore or maintain power to propulsion, steering, and related controls when the main power source fails.”
After a power failure, electrical motors used to maintain propulsion and steering must restart automatically when power is restored, unless remote control starting is provided at the operating station.
46 CFR 143.585(m)“electrical motors used to maintain propulsion and steering must automatically restart when power is restored, unless remote control starting is provided at the operating station.”
Common questions
Do alarms have to be separate from the propulsion control system?
Yes. Alarms must be separate and independent of the control system required by § 143.225.
“Alarms must be separate and independent of the control system required by § 143.225.”
How long must backup electrical sources power propulsion and steering controls?
The two sources of electricity must be capable of powering the needed loads for not less than 3 hours.
“must be capable of powering electrical loads needed to maintain propulsion, steering, and related controls for not less than 3 hours.”
What is required for controls that rely on stored energy like compressed air or batteries?
Propulsion, steering, or related controls directly reliant on stored energy must have two independent stored energy systems that can maintain the vessel's propulsion, steering, and related controls.
“must have two independent stored energy systems, such as compressed air cylinders, battery banks, or hydraulic cylinders,”
Do rudder angle alarms have to avoid nuisance alarms?
Yes. The alarm for a mismatch between ordered rudder angle and actual rudder position must have an appropriate delay and error tolerance to eliminate nuisance alarms.
“This alarm must have an appropriate delay and error tolerance to eliminate nuisance alarms.”
The text of 46 CFR 143.585
Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR
General requirements for propulsion, steering, and related controls on vessels that move tank barges carrying oil or hazardous material in bulk
(a) There must be an alternate means to control the propulsion and steering system which must:
(1) Be independent of the primary control required by § 143.225;
(2) Be located at or near the propulsion and steering equipment; and
(3) Be readily accessible and suitable for prolonged operation.
(b) There must be a means to communicate between each operating station and the alternate propulsion and steering controls.
(c) There must be a means to stop each propulsion engine and steering motor from each operating station.
(d) The means to monitor the amount of thrust, rudder angle, and if applicable, direction (ahead or astern) of thrust must be independent of the controls required by § 143.225.
(e) The propulsion control system required by § 143.225 must be designed so that, in the event of a single failure of any component of the system, propeller speed and direction of thrust are maintained or reduced to zero.
(f) On a towing vessel with an integrated steering and propulsion system, such as a Z-drive, the control system required by § 143.225 must be designed so that, in the event of a single failure of any component of the system, propeller speed and direction of thrust are maintained or the propeller speed is reduced to zero.
(g) An audible and visual alarm must actuate at each operating station when:
(1) The propulsion control system fails;
(2) A non-follow up steering control system fails, if installed; and
(3) The ordered rudder angle does not match the actual rudder position on a follow-up steering control system, if installed. This alarm must have an appropriate delay and error tolerance to eliminate nuisance alarms.
(h) Alarms must be separate and independent of the control system required by § 143.225.
(i) A means of communication must be provided between each operating station and any crewmember(s) required to respond to alarms.
(j) The two sources of electricity required by § 143.555(a)(3) and (b)(8) must be capable of powering electrical loads needed to maintain propulsion, steering, and related controls for not less than 3 hours.
(k) The second source of supply required by § 143.555(a)(3) must automatically start to help restore or maintain power to propulsion, steering, and related controls when the main power source fails.
(l) Propulsion, steering, or related controls that are directly reliant on stored energy, such as compressed air, battery power, or hydraulic pressure, must have two independent stored energy systems, such as compressed air cylinders, battery banks, or hydraulic cylinders, that are capable of maintaining the vessel's propulsion, steering, and related controls.
(m) After a power failure, electrical motors used to maintain propulsion and steering must automatically restart when power is restored, unless remote control starting is provided at the operating station.
Sections it refers to
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.