TL;DR — The QMED Electrician/Refrigerating Engineer exam tests auxiliary machinery, lubrication systems, steering gear, pumps, heat exchangers, and related mechanical systems; key regulatory thresholds include the 28-second rudder-swing requirement for main steering gear and the mandatory independent auxiliary lube pump for pressure-lubricated main propulsion machinery.
What the Rule Says
Examination Scope
Before a QMED endorsement as Electrician/Refrigerating Engineer is issued, the applicant must demonstrate knowledge — by oral or other examination conducted only in English — of all subjects listed in 46 CFR §12.505(c). 46 CFR §12.505
For this rating, the mechanical and auxiliary systems subjects required include: auxiliary machinery, bearings, deck machinery, drawings and tables, heat exchangers, hydraulic principles, instrumentation principles, lubrication principles, maintenance procedures, measuring instruments, pipes/fittings/valves, pumps/fans/blowers, refrigeration principles, remote control equipment, and steering.
Note that several subjects required of other QMED ratings — such as watch duties, properties of fuel, ballast, bilge, desalination, potable water, sanitary/sewage, and most steam and motor propulsion subjects — are not required for the Electrician/Refrigerating Engineer. Knowing what is and is not on your exam list is itself exam-relevant.
Lubricating Oil Systems
The regulatory requirements for shipboard lubricating oil systems are found in 46 CFR §56.50-80. The following provisions are directly testable: 46 CFR §56.50-80
Design inclination standard. The lubricating oil system must be designed to function satisfactorily when the vessel has a permanent 15° list and a permanent 5° trim.
Independent auxiliary lube pump. When pressure or gravity-forced lubrication is employed for the main propelling machinery, an independent auxiliary lubricating pump must be provided.
Oil coolers. Oil coolers must be provided with two separate means of circulating water through the coolers.
Internal combustion engine exemptions. For internal combustion engine installations, the requirements for the independent auxiliary lube pump and the two separate cooling-water means for oil coolers do not apply to vessels in river and harbor service, nor to any vessel below 300 gross tons.
Coolant circulation — ICE. For internal combustion engines, two separate means must be provided for circulating coolant; one of those means must be independently driven and may consist of a connection from a pump of adequate size normally used for other purposes.
Oil filters — ICE. Oil filters must be provided on all internal combustion engine installations. On main propulsion engines fitted with full-flow type filters, the arrangement must allow filters to be cleaned without interrupting the oil supply — except that this is not required on vessels having more than one main propulsion engine.
Piping independence. Lubricating oil piping must be independent of other piping systems and must be provided with necessary coolers, heaters, and filters for proper operation. Oil heaters must be fitted with bypasses.
Dry sump diesel engines. Diesel engine lubrication systems must be arranged so that vapors from the sump tank may not be discharged back into the engine crankcase of engines of the dry sump type.
Steam turbine automatic shutdown. Steam turbine driven propulsion and auxiliary generating machinery depending on forced lubrication must be arranged to shut down automatically upon failure of the lubricating system.
Emergency lube supply — steam propulsion. Steam driven propulsion machinery must be provided with an emergency supply of lubricating oil that operates automatically upon failure of the lubricating oil system. The emergency supply must be adequate to provide lubrication until the equipment comes to rest during automatic shutdown.
Sight-flow glasses. Sight-flow glasses may be used in lubricating oil systems provided they can withstand exposure to a flame at a temperature of 927 °C (1,700 °F) for one hour without appreciable leakage.
Main and Auxiliary Machinery — General
46 CFR Part 58 contains requirements for the design and construction of main and auxiliary machinery installed on vessels. 46 CFR §58.01-1 The applicable standards established by the ABS Marine Vessel Rules may be used as the standard for design, construction, and testing of main and auxiliary machinery except as modified in Subchapter F. 46 CFR §58.01-5
For smaller vessels, 46 CFR §182.100 states that machinery and equipment installed on each vessel must be suitable for the vessel and its operation and for the purpose intended, and must be installed and maintained to afford adequate protection from fire, explosion, machinery failure, and personnel injury. 46 CFR §182.100
Auxiliary machinery of the internal combustion piston type must comply with the provisions of 46 CFR Part 182. Auxiliary machinery of the steam or gas turbine type receives separate consideration under Subchapter F as determined by the cognizant OCMI. Auxiliary boilers and heating boilers also receive separate consideration, except that heating boilers must be tested or examined every three years. 46 CFR §182.310
Steering Gear Systems
Steering gear is a required subject for the Electrician/Refrigerating Engineer QMED exam. The governing regulations are 46 CFR §58.25-5 and §58.25-10.
Definitions to know. The auxiliary steering gear is 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. The main steering gear is the machinery, including power actuating systems, and the means of applying torque to the rudder stock necessary for moving the rudder in normal service. A steering-gear power unit means: for electric steering gear, an electric motor and its associated electrical equipment including motor controller, disconnect switch, and feeder circuit; for electro-hydraulic steering gear, an electric motor, connected pump, and associated electrical equipment; for hydraulic steering gear, the pump and its prime mover. 46 CFR §58.25-5
Independence requirement. Each self-propelled vessel must be provided with a main steering gear and an auxiliary steering gear arranged so that failure of one will not render the other inoperative, and transfer from main to auxiliary can be effected quickly. Power-operated main and auxiliary steering gear must be separate and independent systems. 46 CFR §58.25-10
Steering gear independence from other systems. Steering gear must be separate and independent of all other shipboard systems, except: electrical switchboards from which they are powered; automatic pilots and similar navigational equipment; and propulsion machinery for an integrated system of propulsion and steering. No thruster may count as part of a vessel's required steering capability except on a vessel with an integrated system of propulsion and steering.
Main steering gear performance standard. The main steering gear must be capable of moving the rudder from 35° on either side to 35° on the other at maximum ahead service speed and deepest loadline draft, and from 35° on either side to 30° on the other in not more than 28 seconds under the same conditions. Power operation is required when the rudder stock diameter exceeds 12 centimeters (4.7 inches) in way of the tiller.
Auxiliary steering gear performance standard. The auxiliary steering gear must be capable of moving the rudder from 15° on either side to 15° on the other in not more than 60 seconds with the vessel at deepest loadline draft and running at one-half maximum ahead service speed or 7 knots, whichever is greater. Power operation is required when the rudder stock diameter exceeds 23 centimeters (9 inches) in way of the tiller.
When auxiliary steering gear is not required. No auxiliary steering gear need be fitted when the main steering gear includes two or more identical power units, subject to specific conditions for passenger vessels, cargo vessels, and vessels on international voyages. No auxiliary means of steering is required on a double-ended ferryboat with independent main steering gear fitted at each end.
Large vessels. In each vessel of 70,000 gross tons or over, the main steering gear must have two or more identical power units.
Rudder steadying. Except for tank vessels 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.
Why It Matters on the Exam
Exam questions on this topic cluster around three areas:
1. Numerical thresholds — The 28-second and 60-second rudder-swing requirements, the 15°/5° list/trim design standard for lube systems, the 927 °C sight-glass flame test, the 12 cm and 23 cm rudder stock diameter thresholds for power-operated steering, and the 300 gross ton and 70,000 gross ton vessel size cutoffs are all prime candidates for multiple-choice distractors.
2. System independence — Questions frequently test whether a candidate knows that lube oil piping must be independent of other piping systems, that main and auxiliary steering gear must be separate and independent, and that thrusters do not count toward required steering capability.
3. Automatic safety features — Steam turbine machinery with forced lubrication must shut down automatically on lube failure; steam propulsion machinery must have an emergency lube supply that operates automatically. These automatic-action requirements are frequently tested.
The Electrician/Refrigerating Engineer rating is specifically required to know steering as a shipboard equipment and systems subject, along with lubrication, compressed air, refrigeration, air conditioning, and heating/ventilation — but is not tested on ballast, bilge, potable water, or sanitary/sewage systems. 46 CFR §12.505
Common Pitfalls
Confusing the rudder-swing time limits. Main steering gear: 35°-to-30° in 28 seconds. Auxiliary steering gear: 15°-to-15° in 60 seconds. Candidates frequently invert these or misremember the angles. 46 CFR §58.25-10
Misapplying the ICE exemptions. The independent auxiliary lube pump and dual oil-cooler cooling-water requirements do not apply to ICE installations on vessels below 300 GT or in river and harbor service. Candidates sometimes apply the full requirement to all vessels. 46 CFR §56.50-80
Confusing the rudder stock diameter thresholds. Power operation of the main steering gear is required above 12 cm (4.7 in); power operation of the auxiliary steering gear is required above 23 cm (9 in). These are different thresholds for different gear.
Assuming thrusters count as steering. A bow or stern thruster does not count as part of required steering capability unless the vessel has an integrated propulsion and steering system. 46 CFR §58.25-5
Forgetting the bypass on oil heaters. Oil heaters in lube systems must be fitted with bypasses — a detail that appears in fill-in and multiple-choice formats.
Misidentifying the automatic shutdown trigger. The automatic shutdown on lube failure applies to steam turbine driven propulsion and auxiliary generating machinery. The automatic emergency lube supply applies to steam driven propulsion machinery. These are related but distinct requirements.
Quick Check
Q1: What is the maximum time allowed for the main steering gear to move the rudder from 35° on one side to 30° on the other, at maximum ahead service speed and deepest loadline draft?
28 seconds. 46 CFR §58.25-10
Q2: At what vessel angle of list and trim must the lubricating oil system be designed to function satisfactorily?
A permanent 15° list and a permanent 5° trim. 46 CFR §56.50-80
Q3: When is power operation of the auxiliary steering gear required based on rudder stock diameter?
When the diameter of the rudder stock exceeds 23 centimeters (9 inches) in way of the tiller, excluding strengthening for navigation in ice.
Q4: What must happen automatically when the lubricating system fails on steam turbine driven propulsion and auxiliary generating machinery?
The machinery must be arranged to shut down automatically upon failure of the lubricating system.
Q5: May a sight-flow glass be used in a lubricating oil system, and if so, what is the test standard?
Yes. Sight-flow glasses may be used provided they can withstand exposure to a flame at a temperature of 927 °C (1,700 °F) for one hour without appreciable leakage.
Q6: Does the requirement for an independent auxiliary lubricating pump apply to an internal combustion engine installation on a 250 GT vessel in coastal service?
No. For internal combustion engine installations, that requirement does not apply to any vessel below 300 gross tons.
Q7: Can a bow thruster be counted toward a vessel's required steering capability?
No, except on a vessel with an integrated system of propulsion and steering. [46 CFR §58.25