Navigation Rules vs Shellback
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
- COLREGs and Inland Navigation Rules
- Annotated table of contents
- Search function
- Favorites page
- Email sharing
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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
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.
- 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
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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
Verdict
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
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.
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.
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.
| Parameter | Navigation Rules | Shellback |
|---|---|---|
| Price | $3.99 | Free — better |
| Rating | 4.8 (389 ratings) — better | 3.2 (38 ratings) |
| Positive reviews | 85.7% of reviews — better | 45.2% of reviews |
| Number of ratings | 389 — better | 38 |
| Update frequency | Every 4 months — better | Every 11 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 9.3 — better | 15.0 |
| Further details — not scored | ||
| Size | 35 MB | 89 MB |
| Age rating | +4 | 12+ |
| Developer | Calculated Industries | Program Executive Office for Enterprise Information Systems, Sea Warrior Program |
Customer experience
Navigation Rules
Shellback
User reviews
Navigation Rules
From 389 App Store ratingsWhat 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 ratingsWhat 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 moreShow fewer
- 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 moreShow fewer
- 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 moreShow fewer
- 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
Navigation Rules
No in-app purchases
Shellback
No in-app purchases




