Navy Enlisted Classification

The Navy Enlisted Classification (NEC) system supplements the rating designators for enlisted members of the United States Navy. A naval rating and NEC designator are similar to the Military Occupational Specialty (MOS) designators used in the U.S. Army and U.S. Marine Corps and the Air Force Specialty Code (AFSC) used in the U.S. Air Force.
The U.S. Navy has several ratings or job specialties for its enlisted members. An enlisted member is known by the enlisted rating, for example, a Machinist's Mate (or MM or by the enlisted rate, for example Petty Officer First Class (or PO1). Often Navy enlisted members are addressed by a combination of rating and rate. In this example, this machinist's mate petty officer first class may be addressed as Machinist's Mate 1st Class (or MM1).
However, the NEC designator is a four-digit code that identifies skills and abilities beyond the standard (or outward) rating designator. According to the Military Personnel Manual (MILSPERMAN) 1221-010, the NEC designator facilitates personnel planning, procurement, and selection for training; development of training requirements; promotion, distribution, assignment and the orderly call to active duty of inactive duty personnel in times of national emergency or mobilization.
For example, a person holding the MM-3385 is a nuclear-trained machinist's mate for surface ships, and a person with an MM-3355 is a nuclear-trained machinist's mate for submarines.
In the U.S. Navy's officer ranks, the naval officer designator serves a similar purpose.
01 Deck Department.
0160 - Causeway Barge Ferry Pilot PO2-MCPO
0161 - YTB/YT Tugmaster PO1-MCPO
0164 - Patrol Boat Coxswain SN-PO1
0167 - LCAC Operator CPO-MCPO
0169 - Causeway Barge Ferry Coxswain PO3-PO1
0170 - Surface Rescue Swimmer SN-MCPO
0171 - Landing Craft Utility Craftmaster PO1-MCPO
0172 - LCAC Loadmaster SN-PO1
0181 - Navy Lighterage Deck Supervisor PO3-PO1
0190 - Force Protection Boat Coxswain PO3-PO1
0199 - Boatswain's Mate Basic
02 Navigation Department.
0202 - Assistant Navigator PO1-MCPO
0215 - Harbor/Docking Pilot PO1-MCPO
0299 - Quartermaster Basic
03 Operations Department.
0302 - AN/SYS-2 Integrated Automatic Detection and Tracking (IADT) Systems Operator SN-CPO
0304 - LCAC Radar Operator/Navigator PO2-CPO
0318 - Air Intercept Controller PO2-PO1
0319 - Supervisory Air Intercept Controller PO1-MCPO
0324 - ASW/SUW Tactical Air Controller (ASTAC) PO2-MCPO
0327 - Sea Combat Air Controller (SCAC) SN-CPO
0328 - ASW/ASUW Tactical Air Control (ASTAC) Leadership CPO-MCPO
0334 - HARPOON (AN/SWG-1A) Engagement Planning Operator PO3-MCPO
0336 - Tactical/Mobile (TacMobile) Operations Control (OPCON) Operator SN-CPO
0340 - Global Command and Control System Common Operational Picture/Maritime 4.X (GCCS COP/M 4.X) Operator SN-MCPO
0342 - Global Command and Control System Common Operational Picture/Maritime (GCCS COP/M) Operator SN-MCPO
0345 - Joint Tactical Ground Station (JTAGS)/Multi-Mission Mobile Processor (M3P) System Operator/Maintainer PO3-CPO
0346 - AEGIS Console Operator Track 3 SN-MCPo
0347 - Ship Self Defense System (SSDS) MK1 Operator SN-PO1
0348 - Multi-Tactical Digital Information Link Operator (TADIL) PO3-MCPO
0349 - SSDS MK 2 Advanced Operator SN-CPO 
0350 - Interface Control Officer (ICO) PO1-MCPO
0356 - Global Command and Control System-Maritime (4.1) Increment 2 (GCCS-M 4.1 Inc 2) Operator SR-MCPO
0399 - Operations Specialist Basic
1523 - AN/SPN-35 Amphibious Air Traffic Control Radar Technician
04 Sonar Technician (Submarine/Surface).
0402 - AN/SQQ-89(V)2/9 Active Sonar Level II Technician/Operator Petty Officer -Chief
0410 - AN/SLQ-48(V) Mine Neutralization Systems (MNS) Operator/Maintenance Technician SN-MCPO
0411 - AN/SQQ-89(V)4/6 Sonar Subsystem Level I Operator SN-PO1
0414 - AN/SQQ-89(V)3/5 Active Sonar Level II Technician/Operator PO3-SCPO
0415 - AN/SQQ-89(V) 2/3/4/6/7/8/9/12 Passive Sonar Level II Technician/Operator PO3-SCPO
0416 - Acoustic Intelligence Specialist PO1-MCPO
0417 - ASW Specialist CPO-MCPO
0425 - AN/BQQ-6 TRIDENT LEVEL III Master Operation and Maintenance Technician PO2-MCPO
0430 - Underwater Fire Control System MK-116 MOD 7 Anti-Submarine Warfare Control System Operator PO2-MCPO
0450 - Journeyman Level Acoustic Analyst PO2-MCPO
0455 - AN/SQQ-89(V) 4/6 Active Sonar Level II Technician PO3-SCPO
0461 - AN/BSY-2(V) Advanced Maintainer PO3-MCPO
0466 - Journeyman Surface Ship USW Supervisor PO2-SCPO
0501 - Sonar (Submarines) Leading Chief Petty Officer PO1-MCPO
0505 - Integrated Undersea Surveillance System (IUSS) Analyst SN-SCPO
0506 - Integrated Undersea Surveillance System (IUSS) Maintenance Technician SN-SCPO
0507 - Integrated Undersea Surveillance System (IUSS) Master Analyst PO2-SCPO
0509 - AN/SQQ-89 (V) Adjunct Subsystem Level II Technician PO3-SCPO
0510 - AN/SQS-53D Sensor Subsystem Level II Technician/Operator SSN-CPO
0511 - AN/SQQ-89(V) 11/12 Sonar Subsystem Level I Operator SN-PO1
0512 - AN/BSY-1 and AN/BQQ-5E Combined Retained Equipment Maintenance Technician PO3-SCPO
0518 - Sonar Technician AN/BQQ-10(V) Operator/Maintainer PO3-SCPO
0520 - Sonar, Combat Control and Architecture Equipment Technician PO2-SCPO
0521 - AN/SQQ-89(V)15 Sonar System Level I Operator SN-PO1
0522 - AN/SQQ-89(V)15 Sonar System Level II Technician PO3-MCPO
0523 - AN/SQQ-89(V)15 Sonar System Journeyman PO2-SCPO
0524 - AN/SQQ-89A(V)15/(V)15 EC204 Surface Ship USW Combat Systems Senor Operator SN-PO1
0525 - AN/SQQ-89A(V)15 Surface Ship USW Combat Systems Maintenance Technician PO3-SCPO
0527 - AN/SQQ-89A(V)15/(V)15 EC204 Surface Ship USW Combat Systems Journeyman PO2-CPO
0530 - AN/BQQ-10(V) TI-10/12 Operator/Maintainer PO3-SCPO
0540 - AN/SQQ-34C (V) 2 Aircraft Carrier Tactical Support Center (CV-TSC) Operator PO3-SCPO
0541 - AN/SQQ-34C (V) 2 Aircraft Carrier Tactical Support Center (CV-TSC) Maintenance Technicians PO3-PO1
0550 - Integrated Undersea Surveillance System (IUSS) Passive Sensor Operator (PSO) SN-SCPO
0551 - Integrated Undersea Surveillance System (IUSS) Supervisor PO2-SCPO
0552 - Integrated Undersea Surveillance System (IUSS) Low Frequency Active (LFA)/Compact Low Frequency Active (CLFA) Operator SN-SCPO
0553 - Integrated Undersea Surveillance System (IUSS) SURTASS Mission Commander CPO-MCPO
08 Weapons Department.
0746 - Advanced Undersea MK-46 Maintenance Weapons Smith (SN-SCPO)
0812 - Small Arms Marksmanship Instructor (PO2-MCPO)
0814 - Crew Served Weapons (CSW) Instructor (PO2-MCPO)
0857 - 25mm Machine Gun System (MGS) MK 38 MOD Gun Weapon System (GWS) Technician (SN-PO1)
0870 - MK 46 MOD 2 Gun Weapon System (GWS) Technician (SN-SCPO)
0878 - MK-75 Operator/Maintainer (SN-CPO)
0879 - 5"/54 Caliber Gun System MK-45 MOD 1 and 2 Operator/Maintainer (SN-SCPO)
0880 - 5”/62-Caliber MK 45 MOD 4 Gun Mount Maintenance (SN-SCPO)
0979 - MK-41 VLS Baseline IV Through VII Technician (SN-MCPO)
0981 - MK-41 VLS Maintainer Technician (SN-MCPO)