Machinist’s Mate – Submarine, Auxiliary (MMA): Navy Reserve

Submarines stay hidden. Underwater, repair options are limited.

As a Navy Reserve Machinist’s Mate – Submarine, Auxiliary (MMA), you keep the boat’s support systems running. You maintain hydraulics, air systems, pumps, valves, and other auxiliary gear. Your work helps the submarine run safely and stay ready for duty.

Ready to dive deeper? Keep reading.

Job Role and Responsibilities

Machinist’s Mate – Submarine, Auxiliary (MMA) in the Navy Reserve maintains and repairs mechanical systems aboard submarines. They operate air, hydraulic, and emergency systems that keep the submarine mission-ready.

MMA personnel in the Navy Reserve perform technical support for active-duty submarines. They operate and repair auxiliary equipment undersea.

Daily Tasks

Submarine ITRs handle a wide array of essential technical duties each day. These responsibilities require not only mechanical skill but also precise attention to operational integrity and safety protocols.

Key daily tasks include:

• Operating onboard systems such as hydraulics, refrigeration units, air circulation, and ventilation mechanisms
• Performing routine maintenance on auxiliary machinery and critical damage control equipment
• Troubleshooting technical issues, identifying faults in mechanical systems, and executing necessary repairs
• Overseeing system operations, supervising equipment functionality, and maintaining accurate technical records

This role blends hands-on engineering with real-time problem-solving, demanding both physical coordination and mental agility.

Specific Roles

MMAs serve in technical positions aboard submarines, each assigned specific Navy Enlisted Classifications (NECs). These roles define their responsibilities and areas of expertise.

Mission Contribution

MMA personnel sustain the submarine’s mechanical readiness. They keep life-support and emergency systems operational undersea. Their work secures the vessel’s endurance and survivability.

Technology and Equipment

MMAs operate air compressors, diesel engines, refrigeration units, and hydraulic tools. They work with submarine-specific damage control systems and classified machinery.

Work Environment

Machinist’s Mates (Auxiliary) work in a tight, structured setting where equipment problems can affect the whole boat. The culture is procedure-driven. Space stays limited. The mission sets the pace.

Setting and Schedule

MMAs spend most of their time in mechanical compartments and support spaces. These areas can feel crowded, so careful movement and constant awareness matter. Most work stays indoors, and the schedule shifts when the submarine goes underway.

• Primary location: Submarines and shore facilities that support submarines
• Physical conditions: Confined spaces, tight quarters, loud machinery
• Work rhythm: Rotating shifts, including nights and weekends
• Deployment model: Longer patrols with limited time ashore

Daily work can follow a steady routine, then change fast when a system acts up or the boat shifts to a new operating plan.

Leadership and Communication

Clear direction keeps work safe and consistent. MMAs operate within a defined chain of command, and they follow engineering instructions closely.

• Orders move through senior enlisted leadership and engineering supervisors to the MMA team
• Communication stays technical and procedure-based, with time limits when systems fail
• Feedback often comes through formal reviews and after-action discussions

This structure limits confusion and supports repeatable performance.

Team Dynamics and Autonomy

The work relies on small teams, but each person still owns their actions and results. MMAs coordinate tasks, share updates, and back each other up during troubleshooting.

• Small teams handle specific equipment and maintenance tasks
• Independent diagnostics and repairs are common once a plan is set
• Underway issues can require quick decisions by the person closest to the problem

Teamwork stays constant, and personal accountability stays just as strong.

Job Satisfaction and Retention

The job can feel straightforward in a good way. You see the impact in systems that run, alarms that stay quiet, and equipment that holds up during long stretches at sea.

• Retention often stays moderate
• Many MMAs value the skill growth and direct mission support
• Long deployments and isolation can lead to burnout for some Sailors

For people who like hands-on mechanical work and clear standards, this environment can be a solid fit. For others, the tight spaces and long underway periods can wear down motivation over time.

Training and Skill Development

Initial Training

MMAs complete Navy Recruit Training followed by specialized technical instruction.

Advanced Training

Opportunities exist for NEC-specific and leadership courses. MMAs may qualify for advanced technical schools in damage control, atmosphere control, or diesel systems.

The Navy supports development through rate-specific C-Schools and leadership academies.

Physical Demands and Medical Evaluations

Physical Requirements

MMAs meet Navy Reserve physical fitness standards and perform physically demanding tasks daily. Work requires frequent lifting, climbing, crawling, and working in confined spaces aboard submarines.

Physical Readiness Test (PRT) – Navy Reserve

Medical Evaluations

MMAs must pass a Navy physical exam and submarine duty medical screening.

Periodic medical evaluations include audiograms, cardiovascular assessments, and fitness-for-duty exams.

Submarine-specific clearances require pressure and respiratory capability testing.

Deployment and Duty Stations

Deployment Details

Navy Reserve MMAs deploy for periods between 3 and 12 months. They crew submarines during patrols and extended undersea operations.

They also deploy to submarine tenders and forward maintenance units. Their mission is to maintain readiness, repair systems, and sustain combat capability at sea.

Deployments cover both Atlantic and Pacific theaters. MMAs operate aboard submarines in contested waters and strategic patrol zones.

Shore assignments send them to submarine bases, repair yards, and forward-deployed facilities.

Location Flexibility

Submarine Reserve MMAs receive orders based on fleet demands. Groton, Kings Bay, Bangor, Pearl Harbor, Guam, and Diego Garcia are common assignments.

Reservists request duty stations through official channels, but the fleet dictates placement. MMAs serve where submarines are stationed and where repairs are needed.

Career Progression and Advancement

Career Path

Navy Reserve MMAs follow a defined path from apprentice to senior technical leader.

Promotion and Growth Opportunities

MMAs advance based on performance evaluations, time-in-rate, and exam scores. Leadership courses and advanced NEC qualifications improve promotion chances.

Chief Petty Officer (E-7) marks a key leadership milestone, unlocking supervisory and departmental command roles.

Specialization Opportunities

MMAs can pursue specialized NECs, such as:

• 4230: Submarine Auxiliary Systems Technician
• 9502: Instructor
• 4805: Diesel Engine Inspector
• 4206: Atmosphere Control Equipment Technician

The complete list was provided in an earlier section.

Role Flexibility and Transfers

MMAs may transfer into related mechanical or engineering roles within the Navy Reserve.

Lateral moves to damage controlman or engineering technician positions are common. Requests follow Navy Reserve guidelines and require command approval.

Performance Evaluation

MMAs are evaluated through Enlisted Advancement Worksheets (EAW) and periodic command reviews.

Leadership, technical skills, and system readiness drive advancement decisions. Consistent, high-performance ratings enable promotion and specialized duty assignments.

Salary and Benefits

Financial Benefits

Reserve pay is based on your pay grade, years of service, and the type of orders you are on. DFAS publishes the 2026 reserve drill pay table.

The examples below use 2 years or less of service, a standard drill weekend (4 drills), and 14 days of annual training.

Estimated annual total assumes 12 drill weekends (48 drills) and 14 days of annual training. Taxes, allowances, and special pays can change the total.

When you are on active duty orders, you are paid using the 2026 active duty basic pay table and may qualify for allowances like housing (BAH) and food (BAS). See the BAS rates.

Other pay items can apply based on your assignment and qualifications:

• Career Sea Pay: If you are assigned to qualifying sea duty while on active orders, you may receive career sea pay.
• Submarine Duty Incentive Pay: Qualified Sailors assigned to submarine duty can receive monthly submarine pay while on active orders.

Additional Benefits

• Healthcare: TRICARE Reserve Select is available for many drilling Reservists, with premiums and eligibility that can change by plan year.
• Retirement: Retirement points and a Reserve retirement for qualifying service (often described as 20 good years).
• Education: GI Bill and other education benefits may be available based on eligibility and service.
• Other benefits: Commissary and exchange access, VA home loan eligibility, and other benefits based on status and time in service.

Risk, Safety, and Legal Considerations

This job is technical, but it also carries real risk. MMAs work around machinery that can injure people and damage the boat if handled wrong. They also work under strict Navy rules that leave little room for improvising.

Job Hazards

MMAs work near moving equipment and pressurized systems every day. Many tasks involve heat, noise, and tight spaces, so small mistakes can cause serious harm.

• Rotating shafts, pressurized lines, and chemical systems are part of routine work
• A wrong step on hydraulics, air, or ventilation equipment can trigger bigger failures
• Fires, flooding, and toxic air events carry higher consequences on a submarine
• At sea, outside help can be delayed or not available

Each system supports the crew. Each system can also hurt people if it fails or if someone handles it unsafely.

Safety Protocols

Safety procedures are required, not optional. MMAs follow written steps and get supervision when the job calls for it.

• Lockout/tagout is used before maintenance on systems that can energize or move
• Damage control drills train the crew for fire, flooding, and air hazards
• PPE is required for technical work, based on the task and the hazard
• NAVOSH standards guide tool use, maintenance steps, and documentation
• Supervisor oversight helps confirm compliance and corrects problems early

The goal is simple. Prevent injuries. Prevent equipment damage. Keep the submarine safe.

Security and Legal Requirements

Submarine work involves sensitive spaces and strict accountability. Many billets also require formal screening.

• A Secret clearance may be required. Reviews can include finances, background, and conduct
• Medical and mental health screening helps confirm fitness for submarine duty
• Reservists must follow lawful orders, including mobilization when directed
• Some assignments may involve higher-risk locations and operating conditions

Failure to follow orders or procedures can lead to discipline under the UCMJ, depending on the situation and the severity.

Impact on Family and Personal Life

Family Considerations

Submarine Reserve duty can strain family life. The schedule stays set, and the Navy may not allow regular communication during some periods.

• Long absences and irregular mobilizations can disrupt home routines
• Some underway periods can limit contact for long stretches
• Many families use support services, such as readiness resources and counseling, to manage separation
• Reservists still juggle two lanes: Navy obligations and civilian work or school

This lifestyle affects the Sailor and the people at home. Planning and support help, but the strain is real.

Relocation and Flexibility

Reserve service often stays closer to home, but it still follows Navy needs.

• Many Reservists drill near their home unit. Mobilization can send them to submarine bases or overseas sites
• Moves can happen on short notice, and timelines can change
• Geographic stability is possible, but the contract requires flexibility

Home life can stay steady for long periods. Activation can change that fast.

Post-Service Opportunities

Transition to Civilian Life

MMA training can transfer well to civilian work that values mechanical skill, safety habits, and careful maintenance.

• Common fields include marine engineering, diesel work, HVAC, and industrial maintenance
• Some veterans move into power plants, shipyards, or defense contracting
• Many skills carry over with limited retraining, depending on the job and any required licenses

Transition Assistance Programs

The Navy offers programs that help Sailors plan a move to civilian work.

• Transition workshops can cover job search steps and hiring expectations
• VA counseling and education benefits can support career changes
• Navy COOL (Credentialing Opportunities On-Line) links Navy training to civilian certifications and licenses
• Many programs also offer resume help, interview practice, and job placement support

Civilian Career Prospects

Qualifications and Eligibility

Basic Qualifications

ASVAB Requirements

Application Process

1. Meet with a Navy Reserve recruiter. Discuss eligibility and MMA rating options.
2. Take ASVAB, PiCAT, or AFCT. Verify line scores for MMA qualification.
3. Complete MEPS processing. Medical exam, background check, and security interview.
4. Receive clearance screening. Must qualify for Secret clearance.
5. Choose MMA rating and NEC path. Based on line scores and service needs.
6. Sign enlistment contract. Finalize Reserve agreement.
7. Ship to Recruit Training Command. Complete boot camp, BESS, and “A” School.

Selection Criteria and Competitiveness

MMA applicants compete across several categories:

• ASVAB Line Scores: Higher scores improve selection chances.
• Mechanical Aptitude: Prior trade, vocational, or mechanical work strengthens application.
• Submarine Eligibility: Pass submarine duty physical and psychological screening.
• Fitness Standards: Must meet Navy PRT minimums.
• Leadership Potential: Documented leadership roles enhance competitiveness.

Additionally, Reservists with civilian technical certifications, such as welding, HVAC, or diesel mechanics, increase promotion and billet assignment potential.

Is This a Good Job for You? The Right (and Wrong) Fit

Ideal Candidate Profile

This role fits people who like hands-on mechanical work and stay steady when the pace jumps. You work in tight spaces. Standards stay high. The boat still needs the job done right.

Technical and Personal Traits

Machinist’s Mates (Auxiliary) need physical capability and strong focus. Performance matters most when systems fail or time is short.

• Comfort with tools and mechanical systems is required
• Attention to detail matters, even during stress
• Endurance, patience, and discipline support long patrols and long maintenance days
• Physical strength and mental toughness help in loud, confined spaces
• Tolerance for isolation supports submarine operations and limited personal space

Preferred Backgrounds

These backgrounds can make the transition easier:

• Automotive repair and diagnostics
• HVAC installation or maintenance
• Diesel engine service and overhaul work
• Industrial machinery operation or repair
• Heavy equipment work in construction or manufacturing

People often do well when they enjoy troubleshooting, respect routine, and work effectively in small teams.

Potential Challenges

This job can test both body and mind. Submarine work can feel intense, repetitive, and strict at the same time.

• Confined spaces with heat, vibration, and mechanical noise
• Disrupted sleep from watch schedules and long shifts
• Ongoing fatigue during high-tempo periods
• Limited family contact during some underway periods
• Stress from isolation and mission pressure in close quarters

Misalignment Indicators

This role may be a poor fit if you:

• Need open space and a flexible work setup
• Dislike hands-on labor, machinery, or routine troubleshooting
• Avoid stressful settings or higher-risk work
• Require frequent family contact or regular privacy

Submarine duty works best when you commit early and stay consistent.

Career and Lifestyle Alignment

MMA skills can support civilian work that values mechanical reliability and safety habits. Many people apply this experience in shipyards, power plants, and industrial facilities. Some also pursue maritime maintenance, defense contracting, or other mechanical specialties.

This rating can also build leadership habits. MMAs learn how to direct work, respond during failures, and keep a team calm during high-pressure events.

More Information

If you wish to learn more about becoming an Machinist’s Mate – Submarine, Auxiliary (MMA) in the Navy Reserve, contact your local Navy Enlisted Recruiter. They will provide you with more detailed information you’re unlikely to find online.

You may also be interested in the following related Navy Reserve Enlisted jobs:

• Information Systems Technician – Submarine, Radio (ITR)
• Torpedoman’s Mate (TM)