MM

MM Community Overview
MM Career Path

General Description

Machinist's Mate (Surface) (MM) Machinist's Mates 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. They may also operate and maintain compressed gas producing plants.

What They Do

The duties performed by MMs 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; controlling operation of turbogenerators used to produce electrical power; leaning, 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

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. MMs may be required to perform some heavy physical work. They must be able to work closely with others and, in some cases, with limited supervision.

Requirements ASVAB (Waivers are considered on a case-by-case basis)

VE + AR + MK + AS = 188 or VE + AR + MK + AO = 193

NOTE TEMPORARY ASVAB SCORE IN EFFECT UNTIL 30 SEPTEMBER 2025 ARE AS FOLLOWED VE + AR + MK + AS = 180 or VE + AR + MK + AO = 185

Must have normal hearing

Normal hearing required. Frequencies: 3000hz 4000hz 5000hz 6000hz Average hearing threshold level in these four frequencies must be less than 30db, with no level greater than 45db in any one frequency. If hearing level exceeds these limits, the applicant is enlistment ineligible for the rating.

Helpful links and information

Navy COOL Information (click for Bibliographies, credentialing, and other opportunities)
Surface Engineering (Propulsion - EN/GS/MM) ECM/TECHAD E-mail Contact
Surface Engineering (Auxiliaries - DC/EM/HT/MR) ECM/TECHAD E-mail Contact

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