Marine Corps Enlisted Jobs: Machinist's Mate

This NEC is responsible for maintaining a ship's propulsion

Hispanic soldier saying pledge of allegiance
Blend Images - Hill Street Studios/Erik Isakson/Getty Images

The Navy Enlisted Classification system, called the NEC system, supplements the enlisted rating structure in identifying personnel on active or inactive duty and billets in manpower authorizations. NEC codes identify a non-rating wide skill, knowledge, aptitude, or qualification that must be documented to identify both people and billets for management purposes. 

If a Navy police officer such as an MA or Master at Arms receives specialized training as a machinist's mate, he or she would be awarded this NEC.

From that point on, the sailor could be assigned to the duties of this position. 

Job Duties of a Machinist's Mate 

A machinist's mate is generally responsible for maintaining, repairing, and running the ship's engine and corresponding machines and equipment. This might include boilers, pumps, and heat exchangers. Machinist's mates can work on submarines or surface vessels, but they spend much of their time in the engine rooms in either case. Skills can be learned through on-the-job training or in special training classes. 

Some machinist's mates might qualify for work on nuclear propulsion systems. Certain submarine machinist's mates are enlisted from the ranks of hull maintenance technicians and attend a two-month training class to transition to this role as well as that of the emergency welder. 

NECs for the Machinist's Mate Community Area

These are the NECs for the machinist's mate community area:

  • MM-4201 Cryogenics Technician, Overseas Shore Based Equipment Operator/Maintainer (APPLIES TO: MM)
  • MM 4204 Steam Propulsion Maintenance Supervisor (APPLIES TO: MM)
  • MM 4206 Shipboard Engineering Plant Program Manager (APPLIES TO: MM, EM, EN, IC, GSE, GSM, GS)
  • MM-4208 Automated Electrolytic Oxygen Generator (AEOG) Maintenance Technician (APPLIES TO: MM, EM, ET)
  • MM-4222 NAMTS Pump Repair (APPLIES TO: MM, EN, GSM)
  • MM-4223 NAMTS Air Conditioner and Refrigeration (APPLIES TO: MM, EN)
  • MM-4225 NAMTS Boiler Repair Technician (APPLIES TO: MM)
  • MM-4230 SSN/SSBN Auxiliary Equipment Operator (APPLIES TO: MM)
  • MM-4231 SSN/SSBN Auxiliary Equipment Technician (APPLIES TO: MM)
  • MM-4232 SSN/SSBN Weapons Equipment Operator (APPLIES TO: MM)
  • MM-4233 SSN/SSBN Weapons Equipment Technician (APPLIES TO: MM)
  • MM-4234 SSN 774 Class Advanced Auxiliary Equipment Technician (APPLIES TO: MM)
  • MM-4235 SSN 751-773 Submarine Vertical Launch System Tube Maintenance Technician (APPLIES TO: MM, FT)
  • MM 4246 SSN/SSBN Diesel Engine (Fairbanks Morse) Maintenance Technician (APPLIES TO: MM)
  • MM 4247 SSN 719 - 725 and 750 Submarine Vertical Launch System Tube Maintenance Technician (APPLIES TO: MM, FT)
  • MM 4252 Electrolytic Oxygen Generator (Model 6L16) Operator (APPLIES TO: MM, EM, IC)
  • MM-4254 Oxygen Plant Operator/Maintenance Technician (APPLIES TO: MM)
  • MM 4283 High and Low-Pressure Cryogenic Technician (APPLIES TO: MM)
  • MM 4291 Refrigeration and Air Conditioning Systems Technician (APPLIES TO: MM, EN)
  • MM 4295 UNREP Equipment Mechanic (APPLIES TO: MM, EN)
  • MM 4296 Shipboard Elevator Hydraulic/Mechanical System Mechanic (APPLIES TO: MM, EN, TM, GM, AO)
  • MM-4502 Boiler Repair Technician (APPLIES TO: MM)
  • MM-4508 Electronic Automatic Boiler Controls Console Operator (APPLIES TO: MM)
  • MM-4509 Electronic Automatic Boiler Controls Maintenance Technician (APPLIES TO: MM)
  • MM-4513 Automatic Combustion Control (General Regulator) Maintenanceman (APPLIES TO: MM)
  • MM-4533 Automatic Combustion Control Console Operator (General Regulator) (APPLIES TO: MM)
  • MM-4540 NAMTS Valve Repair Technician (APPLIES TO: MM, EN )
  • MM-4541 NAMTS Hydraulics Repair Technician (APPLIES TO: MM, GSM, EN )
  • MM-4542 NAMTS Outside Machinist (APPLIES TO: MM, EN )