MMAMachinist's Mate Auxiliary(MMA Navy Rating)
Machinist''s Mate Auxiliary (MMA) is the submarine non-nuclear mechanical specialty. MMAs own everything aft of the reactor compartment that isn''t primary propulsion: high-pressure air, hydraulics, atmosphere control (CO2 scrubbers, O2 generators, H2 burners), the trim and drain systems, ship''s service turbine generators'' auxiliaries, weapons-handling hydraulics, the outboard plant, and the atmosphere-analysis equipment that keeps the crew alive on long submerged runs.
MMA is a non-nuclear submarine rating distinct from MMN (Machinist''s Mate Nuclear), which runs the primary plant. MMA sailors are the boat''s mechanical generalists — they diagnose and repair across dozens of auxiliary systems and stand watch as Auxiliaryman of the Watch (A-Gang), Chief of the Watch, and Diving Officer of the Watch.
The pipeline runs from Basic Enlisted Submarine School in Groton into MMA ''A'' School, also at Naval Submarine Base New London. Work is physically demanding, hot, and tight-quartered. Civilian translation is strongest toward industrial mechanic, HVAC-R, and maritime engineering trades.
Overall
Quick Stats
- ✓Vision: Corrects to 20/20
- ✓Normal color perception
- ✓Normal hearing
- ✓No speech impediment
Security Clearance
Secret~$3K–$15K civilian sector value
Requires a National Agency Check with Local Agency Check and Credit Check (NACLC). Processing typically takes 1–3 months and is initiated early in your training pipeline.
ASVAB Requirements
AFQT Minimum
50
Who This Is Best For
Best for hands-on mechanical candidates who want submarine duty without the nuclear pipeline, and who are looking toward industrial-mechanic, HVAC-R, or maritime trade careers afterward.
+Pros
- ✓Strong civilian career transition
–Cons
- ✗Significant sea duty
Real Opinions
+Positive
“I kept the air clean. If you want to live under the water in a steel tube that's closed on both ends for months at a time, you need people like me.”
“Proudest work of my life with some of the best men I have ever known.”
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0 charsRecruiter vs Reality
What the recruiter says vs. what it's actually like.
🫡 Recruiter says
“A-Gang keeps the sub habitable — you'll be the hero of the boat.”
MMAs run oxygen generators, CO2 scrubbers, hydraulics, HP air, diesel, and sanitary systems. Retired A-Ganger: "We were in charge of the shit tanks too. If you really want to see grown men cry, shut down those babies for a few hours."
🫡 Recruiter says
“Great for a mechanical civilian career — HVAC, refrigeration, diesel.”
The Navy-to-civilian translation is real, but MMA systems are sub-specific (EAB, CAMS, O2 gens). Generic HVAC/refrigeration employers may not recognize Navy training without extra certs. Civilian diesel/marine-mechanic certs are the most direct path.
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Horror Stories
Real stories people have shared about this rate. Swipe to browse.
“A-Gang owns the sanitary system, and that means A-Gang owns what happens when it fails. There is no polite way to describe blowing sanitaries wrong or clearing a blocked line on a submarine, and every A-Ganger has a story about it. It is the part of the job that never appears in a recruiting conversation and the part that new MMAs talk about for the rest of their lives.”
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0 charsRelated Reading
Guides on picking a rate, ASVAB, bonuses, promotion, and life after the Navy.
Getting Started
How do you choose the right Navy rate for you?
Choosing a Navy rate means weighing your ASVAB scores, lifestyle preferences, civilian career goals, and willingness to deploy or go to sea. Start by identifying which ratings you qualify for, then narrow the list by what matters most to you.
Getting Started
What is the ASVAB and what scores do you need?
The ASVAB is a multi-aptitude test that determines which Navy ratings you qualify for. Your sub-test scores combine into line scores, and each rating has minimum line-score requirements. Higher scores open more options.
Career & Pay
Which Navy rates have the biggest enlistment bonuses in 2026?
Active Component (Active Duty) only. Per the CNRC GENADMIN dated 24 July 2026, the biggest source-rate bonus is $40,000 — Nuclear Field on FY26 ship dates ($75,000 EB cap). Special Warfare Boat Operator (SB) follows at $35,000, then EOD and SEAL (SO) at $30,000, and Aviation Rescue Swimmer (AIRR) and Cryptologic Technician Maintenance (CTM) at $25,000. Special Operations Future Sailors who clear the elevated PST standards add a flat $20,000 EBPST. Most rates cap at $50,000 total EB. The Loan Repayment Program adds up to $65,000 on top, separately. Reserve component (SELRES) bonuses are governed by a different message and are not covered here.