Master vs CBDR
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Master
Learn maritime navigation rules with an interactive system designed for effective retention. This app breaks down complex regulations into manageable sections with visual aids and mnemonics. It revisits incorrect answers and provides instant graphical feedback, making the learning process intuitive and efficient.
- Interactive learning system
- Step-by-step rule guidance
- Mnemonics and memory aids
- Interactive visuals
- Graphical feedback on answers
- Practice section with progress tracking
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Master-Nav is a progressive COLREGS learning system developed by a Master Mariner. The COLREGS are notoriously difficult to learn and retain — Master-Nav makes it significantly easier through an interactive system built around how your brain actually works. Instead of guessing through random question banks, Master-Nav guides you step by step through every rule from start to finish. Wrong answers are revisited until the rules stick — properly. Complex regulations are broken down into learnable chunks — bite-sized sections supported by mnemonics, memory aids and interactive visuals designed around how the brain actually retains information. Every incorrect answer is shown graphically alongside the correct one — immediately clear, no confusion. And with a single tap, the relevant COLREGS rule is accessible from any question at any time. Master-Nav covers COLREGS Parts A to D — General, Steering & Sailing, Lights & Shapes and Sound & Light Signals — plus Annex IV Distress Signals. Over 1000 questions in multiple formats, with a dedicated Practice Section that tracks right, wrong and unanswered so you always know where to focus. COLREGS — the easy way.
CBDR
This app trains junior deck officers and watchstanders in essential radar watch skills, including contact evaluation, COLREGS classification, and generating contact reports. It features a live radar scope, generated scenarios for various navigation situations, and drills for recognition and maneuvering.
- Live radar scope with vectors and trails
- Generated navigation scenarios
- COLREGS classification
- Contact report scoring
- Maneuvering board drills
- Recognition drills
- USCG Rules of the Road test bank
- Offline group testing
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CBDR is a training app for junior deck officers. Eight subjects cover radar, Rules of the Road, maneuvering boards, navigation calculations, positioning, tides and currents, shiphandling, and vessel identification. RADAR. Practice contact assessment, CPA, relative motion and contact reports. Use the scenario library or build a picture with up to six contacts. Edit positions, courses and speeds, then share the scenario by code or QR. Give a report by voice with on-device recognition, or type it. Eleven radar explainers cover the signal, the receiver controls and propagation, and a tuning simulator lets you clear a poor picture while checking that weak returns survive. RULES. Practice with the 954-question Rules of the Road bank and read the governing Navigation Rules passages in the app. Optional Guided Practice directs questions toward material that needs more work. Lights, shapes and sound-signal drills include their rules and explanations. MANEUVERING BOARD. Work nine Pub 1310 problem types with step-by-step constructions, including CPA avoidance, stationing, limiting range, bearings-only TMA, advance and transfer, and wind. Practice a generated problem or enter your own values. CALCULATIONS. Work time, speed and distance, compass conversion, mental minute rules, visibility, anchoring, time zones, ETA and speed of advance. Problems that allow a calculator include one; mental-only exercises are labeled. POSITIONING. Step through visual and radar fixes, soundings, celestial navigation, inertial navigation, GPS, running fixes, dead reckoning, and set and drift. Illustrated plots introduce each construction step by step, with focused labels and interactive controls. Study Aids to Navigation with an animated range and recognition practice. Search the bundled Chart No. 1 plates. Star Finder identifies navigational stars from the camera's star pattern without asking for, computing or storing your position. TIDES AND CURRENTS. Explore animated lessons on tides, reversing flow in San Diego Bay, rotary currents, and hydraulic flow in the Cape Cod Canal. Zoom into the displays and use the clocks, current meter and Moon dial to examine the models. The teaching days are illustrative. A separate lookup retrieves NOAA and Canadian Hydrographic Service station predictions, with saved datasets available offline and export options. SHIPHANDLING. Animated lessons show how a propeller works, how a rudder works, the pivot point under acceleration, restraint and tugs with a live throttle, and twisting off a pier. Man-overboard recoveries step through the Anderson, Williamson and racetrack turns, each opened by its use case. Hydrodynamic effects cover bank cushion and suction, interaction alongside an oiler, and squat, with pressure fields around the hulls. The squat lesson uses an Arleigh Burke class profile and enlarged sonar-dome clearance, with worked clearance and water-speed examples. VESSEL IDENTIFICATION. Recognize ship classes and vessel types from silhouettes, photographs, or both. This feature is marked Beta. Source and license credits accompany the images. CLASSROOM. Host and join group tests using QR or text codes, entirely offline. Return results by QR and export the instructor's record as PDF or CSV. Hosted exams reveal answers after the test is finished. Training works offline. The station-prediction lookup uses the internet when requested, including Apple's map service. No account, advertising, analytics or tracking. Training settings, optional question-level practice progress, custom scenarios and saved predictions stay on the device. There is no history of session scores.
Screenshots
Verdict
The clearest difference is price: CBDR at Free against Master's $1.99. CBDR also leads on rating (5.0 vs 4.7) and update cadence (weekly vs fortnightly). Master's advantage is ratings volume (94 vs 4) and chart position (#93 vs unranked). On ads, in-app purchases 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
CBDR is free to download; Master costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.
CBDR holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: Master has 94 ratings behind it against 4, so its average is the more settled of the two.
Master ships an update fortnightly, CBDR weekly. The most recent releases landed on September 22, 2026 and September 18, 2026 respectively.
| Parameter | Master | CBDR |
|---|---|---|
| Price | $1.99 | Free — better |
| Rating | 4.7 (94 ratings) | 5.0 (4 ratings) — better |
| Positive reviews | 96.9% of reviews | — |
| Number of ratings | 94 — better | 4 |
| Update frequency | Fortnightly | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Best chart rank | #93 — better | — |
| Devices | iPhone, iPod | iPhone, iPad |
| Requires iOS | 15.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 117 MB | 72 MB |
| Age rating | 4+ | 4+ |
| Developer | Peterjohn Chisholm | Sean Bowman |
Customer experience
Master
CBDR
In-app purchases
Master
No in-app purchases
CBDR
No in-app purchases







