Comparison

Navigation Rules vs Shellback

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Navigation Rules

Access the complete International Regulations for Preventing Collisions at Sea (COLREGs) and Inland Navigation Rules. This app provides a searchable, annotated version of boating regulations, ideal for quick reference and sharing information.

Highlights
  • COLREGs and Inland Navigation Rules
  • Annotated table of contents
  • Search function
  • Favorites page
  • Email sharing
Features
Read full description

Navigation Rules contains a complete copy of the International Regulations for Preventing Collisions at Sea, 1972 (COLREGS), including amendments and the Inland Navigation Rules, in effect for all inland waters, including the Great Lakes. App is COLREGs most recent version dated - June 28th, 2019. This app includes an annotated table of contents and a search function to help the reader quickly find the rule and related references. A Favorites page allows quick access to commonly referenced pages. Use the email function to share a page with others. If you are a boater you need to know this information. You might also be interested in our other boating apps: - Boater’s Pocket Reference - Boating Calcs - Seamanship - Ship Captain's Medical Guide

About

Shellback

This app provides US Naval Surface Force personnel with offline access to essential information. It includes manuals and resources for administration, medical, operations, personnel management, safety, and navigation rules. Content is updated annually for relevance.

Highlights
  • Offline access to SURFOR information
  • Admin/Training manuals
  • Medical readiness resources
  • Operations and navigation training
  • Personnel management documents
  • Safety information and lessons learned
  • Rules of the Road quiz
Features
Read full description

What is the Shellback app? Shellback, formerly known as eDivo, is a free mobile app developed to support US Naval Surface Force (SURFOR) personnel in an easy-to-access offline environment. What is a Shellback? In naval tradition, a Shellback is a nickname for a Sailor who has crossed the Equator and thus transitioned from a novice Sailor, or Pollywog, to an experienced Sailor. Why do I need Shellback? Shellback provides Sailors the ability to download key SURFOR information on their own portable devices and access it while underway without the need for an internet connection. Shellback provides the most relevant and current information to SURFOR Sailors in one location. Content is scheduled for annual updates. What type of info can I find in Shellback? The information in Shellback is separated into several main categories: -Admin/Training: Contains the Correspondence Manual and the SURFOR Training and Readiness Manual. -Medical: Includes the Manual of the Medical Department, information on medical and physical readiness, mental health, Medical Evaluation Board procedures, the Disability Evaluation System, family member readiness, and more. -Operations: Includes information and training on bridge management, navigation basics, watch team tools, crew endurance, operating procedures for air-capable ships, Air Certification for Naval Surface Force Ships, and manuals for amphibs, maintenance, and other general ship operation resources. -Personnel Management: Provides documents on Navy personnel policy and administration. Also includes legal handbooks and manuals, resources for Surface Warfare Officers, and a variety of general personnel management resources. -Safety: Provides documents related to lessons learned, mishap reporting, notices, safety-related awards, and general safety resources. -Rules of the Road: This quiz tests a Sailor’s knowledge of maritime navigation rules.

Screenshots

Navigation Rules4 screens
Shellback3 screens

Verdict

The call

The clearest difference is price: Shellback at Free against Navigation Rules's $3.99. Navigation Rules's advantage is rating (4.8 vs 3.2) and review sentiment (86% vs 45%). On ads, in-app purchases, monetization model and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Shellback is free to download; Navigation Rules costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Navigation Rules holds the better App Store score, 4.8 against 3.2. That said, the two scores are not equally well evidenced: Navigation Rules has 389 ratings behind it against 38, so its average is the more settled of the two. Written reviews point the same way: 86% of Navigation Rules's written reviews are positive against 45% of Shellback's.

UpkeepUpdate frequency

Navigation Rules ships an update every 4 months, Shellback every 11 months. The most recent releases landed on November 7, 2026 and November 4, 2026 respectively.

Scorecard6 real differences · 4 level
Navigation Rules versus Shellback: the parameters behind the verdict, then further details
ParameterNavigation RulesShellback
Price$3.99Free — better
Rating4.8 (389 ratings) — better3.2 (38 ratings)
Positive reviews85.7% of reviews — better45.2% of reviews
Number of ratings389 — better38
Update frequencyEvery 4 months — betterEvery 11 months
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS9.3 — better15.0
Further details — not scored
Size35 MB89 MB
Age rating+412+
DeveloperCalculated IndustriesProgram Executive Office for Enterprise Information Systems, Sea Warrior Program

Customer experience

Navigation Rules

All ratings386 ratings
Positive96.4%
Neutral2.6%
Negative1.0%
Written reviews63 reviews
Positive85.7%
Neutral6.3%
Negative7.9%

Shellback

All ratings38 ratings
Positive52.6%
Neutral5.3%
Negative42.1%
Written reviews42 reviews
Positive45.2%
Neutral19.0%
Negative35.7%

User reviews

Navigation Rules

From 389 App Store ratings

What we love

  • 👍 Easy to navigate and user-friendly interface
  • 📚 Comprehensive reference material for navigation rules
  • 🚀 Quick access to rules on-the-go
  • 🎓 Excellent study tool for maritime exams and licenses
  • 📖 Well-organized table of contents and structure

Room to improve

  • 🐛 Poor navigation between rules requires multiple menu presses
  • 📄 Walls of text with limited visual content
  • 🎨 Inconsistent formatting in some sections (e.g., 8F(iii))
  • ❌ Limited additional features beyond basic text content
  • 🔄 Clicking definitions forces users to search for original page again

Shellback

From 38 App Store ratings

What we love

  • 👍 Great all-in-one tool
  • 👍 Useful for all ranks
  • 👍 Good reference tool
  • 👍 Handy for quick lookups
  • 👍 Contains essential references

Room to improve

  • outdated information
  • ❓ ROR quiz lacks correct answers
  • ❓ Uniform regulations not loading
  • ❓ App crashes on feedback
  • ❓ Outdated PFA instruction

Bugs and requests

Navigation Rules

Reported bugs

4 issues
  • Formatting inconsistency in rule 8F(iii)
  • Navigation issues when jumping between non-sequential rules
  • Definition links don't provide easy return to original page
  • Typos present in content

Requested features

7 requests
  • Quiz or test functionality for self-assessment
  • Easier rule-to-rule navigation without menu cycling
  • More visual illustrations and diagrams throughout
  • Back button functionality when accessing definitions
  • Option to separate international and inland rules
Show 2 more
  • Interactive flashcards for light signals
  • Additional bells and whistles beyond basic manual content

Shellback

Reported bugs

8 issues
  • App crashes when trying to enter feedback
  • Uniform regulations documents do not load
  • App crashes on iOS system update
  • App won't open after update
  • App won't download completely
Show 3 more
  • Female uniform regulations don't open
  • Sections highlight but do not open
  • App won't download on new phone

Requested features

25 requests
  • Add more content to the app
  • Provide correct answers for ROR quiz
  • Show COLREGs rule for ROR questions
  • Add underway mode to download all refs
  • Include aviation community instructions
Show 20 more
  • Add Navy Correspondence Manual
  • Include MILPERSMAN
  • Add JJDIDTIEBUCKLE
  • Improve CDB gouge
  • Add reminder tool to calendar
  • Add hyperlinks to current instructions with offline option
  • Include full versions of instructions and training
  • Add more check list instructions
  • Add a more general app version
  • Add more instructions to current app
  • Add Correspondence Manual
  • Add MILPERSMAN
  • Add JJDIDTIEBUCKLE
  • Improve CDB gouge
  • Add reminder tool to calendar
  • Add hyperlinks to current instructions with offline option
  • Include full versions of instructions and training
  • Add more check list instructions
  • Add a more general app version
  • Add more instructions to current app

In-app purchases

None

Navigation Rules

No in-app purchases

None

Shellback

No in-app purchases

Questions

Is Navigation Rules free?
Navigation Rules costs $3.99, with no in-app purchases.
Is Shellback free?
Shellback is free to download, with no in-app purchases.
Which has better reviews, Navigation Rules or Shellback?
Navigation Rules is rated higher. Navigation Rules averages 4.8 out of 5 from 389 ratings, while Shellback averages 3.2 from 38 ratings.
Do Navigation Rules or Shellback have ads?
Neither Navigation Rules nor Shellback shows ads.
Which is updated more often, Navigation Rules or Shellback?
Navigation Rules ships an update every 4 months, and Shellback every 11 months. Most recently, Navigation Rules was updated on November 7, 2026 and Shellback on November 4, 2026.

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