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Navy NEC · Support

T21B Served SSN/SSBN/SSGN Assistant Navigator (ANAV)

Current service use not established

This code is listed in the directory. Inclusion alone does not confirm current service use.

A Navy Enlisted Classification: a skill designation sailors hold in addition to their rating.

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Overview

Served submarine assistant navigators oversee daily celestial computations, prepare input for the Commanding Officer’s Night Orders, and obtain and maintain hydrographic data, charts, publications, advisories, and operational information. They review navigation logs and reports for accuracy and completeness, address errors or omissions, and serve as subject matter experts for navigation inspections and schoolhouse curriculum updates and applications.

Core Skills

  • Solar and lunar event calculation oversight
  • Hydrographic data and navigation publication maintenance
  • Navigation log and report accuracy review
  • Navigation inspection subject matter expertise

Civilian Career Paths

Career associations are editorial assessments of the cited evidence, not an official crosswalk unless the evidence explicitly says so. O*NET supplies civilian occupation information, not proof of a military match. Related experience does not confer civilian qualifications. Tasks and tools below describe civilian work, not military training.

Merchant vessel mate

Maintaining hydrographic data, navigational charts and operational advisories provides a foundation for the navigation-information work of a merchant vessel mate.

How to prepare: Request an official sea-service transcript with vessel particulars, underway time and assigned duties for NMC evaluation; a DD-214 is not acceptable sea-service evidence. Entry depends on USCG-evaluated sea time, the appropriate MMC endorsement, TWIC, and applicable citizenship, medical, drug-testing, training and examination requirements; open-ocean service also requires USCG-verified STCW training.

What the civilian work involves
  • Consult maps, charts, weather reports, or navigation equipment to determine and direct ship movements.
  • Prevent ships under navigational control from engaging in unsafe operations.

Surveying and Mapping Technicians

Maintaining navigational charts and hydrographic information, alongside reviewing navigation records for errors, transfers to map updating and accuracy checks.

How to prepare: Complete a practical ESRI ArcGIS software exercise that updates a map layer and documents errors, corrections and changed information, then use it as a work sample for mapping-focused technician applications.

What the civilian work involves
  • Check all layers of maps to ensure accuracy, identifying and marking errors and making corrections.
  • Monitor mapping work or the updating of maps to ensure accuracy, inclusion of new or changed information, or compliance with rules and regulations.
  • Produce or update overlay maps to show information boundaries, water locations, or topographic features on various base maps or at different scales.
Civilian tools and software (examples)
  • ESRI ArcGIS software

Notes & Sources

Evidence for this guidance (8 documents)
  1. NAVPERS 18068F Vol II (NEOCS, Jul 2026 edition): NEC T21B

    [1] NEC entry "T21B - Served SSN/SSBN/SSGN Assistant Navigator (ANAV)"; cached text line 10674; NAVPERS 18068F Vol II, 2026-07 edition

    Supports: Solar and lunar event calculation oversight, Hydrographic data and navigation publication maintenance, Navigation log and report accuracy review, Navigation inspection subject matter expertise, Merchant vessel mate (O*NET 53-5021.00), Surveying and Mapping Technicians (O*NET 17-3031.00)

  2. O*NET: Captains, Mates, and Pilots of Water Vessels

    [2] O*NET 30.3 occupational data

    Supports: Merchant vessel mate (O*NET 53-5021.00)

  3. USCG National Maritime Center: Military to Mariner (military sea service credit)

    [3] Military Service Requirements section; public page retrieved through Jina Reader 2026-09-23

    Supports: Merchant vessel mate (O*NET 53-5021.00)

  4. USCG National Maritime Center: Apply for Merchant Mariner Credential

    [4] Original, Raise of Grade, and STCW application steps; public page retrieved through Jina Reader 2026-09-23

    Supports: Merchant vessel mate (O*NET 53-5021.00)

  5. Bureau of Labor Statistics: Water Transportation Workers

    [5] How to Become; training, licenses and related experience; updated August 27, 2026, checked September 23, 2026

    Supports: Merchant vessel mate (O*NET 53-5021.00)

  6. USCG: 46 CFR 10.232 military sea-service evidence and credit

    [6] Paragraphs (a) and (d)(1), official eCFR snapshot September 21, 2026; retrieved September 24

    Supports: Merchant vessel mate (O*NET 53-5021.00)

  7. USCG: 46 CFR 11.201 officer-endorsement requirements

    [7] Paragraph (a), official eCFR snapshot September 21, 2026; retrieved September 24

    Supports: Merchant vessel mate (O*NET 53-5021.00)

  8. O*NET: Surveying and Mapping Technicians

    [8] O*NET 30.3 occupational data

    Supports: Surveying and Mapping Technicians (O*NET 17-3031.00)

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