Navy Enlisted Job: Machinist's Mate

These sailors work with all manner of machines and parts

Fleet of military ships at sea in Arabian Gulf, May 2003
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Machinist's Mates (MMs) in the Navy are responsible for maintaining and operating a variety of complex machinery, and assisting machinists in keeping all Navy craft in top working order. Most of the work they do is conducted on machines and engine parts within the hulls of Navy ships and submarines.

For instance, these sailors operate and maintain steam turbines and reduction gears used for ship propulsion and auxiliary machinery such as turbogenerators, pumps, and oil purifiers. They also maintain auxiliary machinery outside of main machinery spaces, such as electrohydraulic steering engines and elevators, refrigeration plants, air conditioning systems and desalinization plants. And, they may also operate and maintain compressed gas producing plants.

Duties Performed by Navy Machinist Mates

Some of the more technical responsibilities of machinist's mates include:

  • aligning piping systems for oil, water, air, and steam, and controlling the operation of ship boilers and steam turbines used for ship propulsion and service systems
  • cleaning, adjusting, testing and performing other preventive maintenance on a ship's boilers, main engines, turbogenerators and other auxiliary machinery including steering engines, elevators, winches, pumps and associated valves
  • operating and maintaining desalinization plants (distilling plants) to make fresh water from sea water
  • maintaining refrigeration plants, air conditioning systems, and galley equipment
  • repairing or replacing valves, pumps, heat exchangers, compressors, steam turbines and hydraulic or pneumatic control devices
  • making entries in and analyzing machinery operating records and reports

Working Environment for Navy Machinist's Mates

Machinist's mates work within the hull of a ship in fire rooms, boiler rooms, engine rooms or shops. These locations are sometimes hot and noisy. Machinist's mates may be required to perform heavy physical work. They must be able to work closely with others and, in some cases, with limited supervision.

Qualifying as a Navy Machinist's Mate

After Navy basic training, these sailors spend eight weeks in technical training (or as the Navy calls it "A school") at the Naval Recruit Training Command in Great Lakes, Illinois.

To be eligible to serve as a Navy machinist's mate, you'll need a combined score of 195 in the verbal (VE), arithmetic (AR), mathematical knowledge (MK) and auto and shop (AS) segments of the Armed Services Vocational Aptitude Battery (ASVAB) tests. You also can qualify with a combined 200 on the VE, AR, MK and assembling objects (AO) segments of the ASVAB tests.

There is no Department of Defense security clearance needed for this job. Normal hearing is required, however, and will be tested prior to granting this rating. Vision must be correctable to 20/20 and normal color vision (no colorblindness) is required to serve as a machinist's mate.

Sea/Shore Rotation for Machinist's Mates

  • First Sea Tour: 54 months
  • First Shore Tour: 36 months
  • Second Sea Tour: 36 months
  • Second Shore Tour: 36 months
  • Third Sea Tour: 36 months
  • Third Shore Tour: 36 months
  • Fourth Sea Tour: 36 months
  • Forth Shore Tour: 36 months

Sea tours and shore tours for sailors that have completed four sea tours will be 36 months at sea followed by 36 months ashore until retirement.