GPT vs Depthly
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
GPT
Real-time marine safety tracking with smart alerts and offline support. This system ensures full visibility and control over your team, even without internet access, and logs all activity for traceability.
- Real-time tracking map
- Advanced alert system (boundary, collision, lost signal)
- Offline operation support
- Black box data logging
- Simulator mode for training
- Smart team management
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Short Description Real-time marine safety tracking with smart alerts, offline support & black box data. Full Description GPT App is the control center for the Gpacers Poseidon Tracking and Rescue System — a patented safety solution designed for marine professionals and water sports users. It integrates real-time positioning, intelligent alerts, offline operation, and black box recording using radio, GPS, internet, and LEO satellite networks. Whether you're diving, sailing, or managing offshore operations, GPT ensures full visibility and control over your team — even without internet access. Key Features: Smart Monitoring Map -- Track team members, passersby, and alert zones in real time. Coordinates, directions, and distances are updated instantly, with intuitive icons for every status. Advanced Alert System -- Boundary Alert: Triggers when a member exits the designated safe zone. -- Collision Alert: Warns of potential collisions within a 120° forward zone. -- Lost Signal Alert: Countdown-based personnel check: activates if no signal is received within 5 minutes. Flexible Connectivity Supports on-site (radio-based) and remote (internet/satellite) data transmission. Operates reliably even without Wi-Fi or mobile networks. Geofencing and Coordinate Settings Customize safety zones and choose between device, receiver, or manual origin settings for accurate tracking. Black Box Function Automatically logs all activity data — like a flight recorder — for full traceability and incident analysis. Simulator Mode for Training Includes a built-in simulator for safe, hands-on training without real-world deployment. Smart Team Management Classify participants as Members or Passersby. View Absent Members and automatically update status when signal is received. Multilingual UI Optimized for international users with language support and intuitive design. Ideal For • Scuba & freedivers • Water sports instructors & operators • Offshore personnel & patrol teams • Marine rescue coordinators • Research expeditions Hardware Requirement This app requires GPT-compatible hardware (e.g., transmitters, receivers, monitoring stations). Visit www.gpacers.com for more info.
Depthly
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Know how deep the water is before you get there. Depthly turns your iPhone into a pocket depth chart for the sea. Aim the crosshair anywhere on the map, tap once, and read the depth of the seabed at that exact spot. No sonar hardware, no cables, and nothing to install on your boat. BUILT FOR PEOPLE ON THE WATER Whether you sail, fish, cruise, paddle or dive, the question is always the same: how deep is it here? Depthly answers it in one tap, using published bathymetric survey data that covers seas around the world, with especially detailed coverage of European waters. TAP TO SOUND Take a sounding anywhere on the chart. Every measurement is saved as a pin with the depth, the exact position in decimal or degrees and minutes, the nearest place name and the time it was taken. Build your own private chart of the places that matter to you: anchorages, fishing marks, shallow passages, dive sites. DEPTH CONTOURS ON ANY MAP Generate depth contour lines for the area on your screen, at the interval you choose, drawn over a marine chart, a satellite view or a standard map. See at a glance where the bottom shelves, where the deep channel runs and where it gets thin. SEABED PROFILES Pick two points and Depthly draws the cross section of the seabed between them, with the total distance, the deepest and shallowest points and the average depth. Perfect for checking a passage, planning a dive or understanding a fishing ground. WORKS COMPLETELY OFFLINE Download the chart and the depth data for a whole cruising area before you leave the marina. Out on the water, with no signal at all, soundings, contours and profiles keep working exactly as they do at home. Your charts do not need the internet once they are on your phone. RECORD YOUR TRACKS Record your route while you are underway. Depthly logs your position and fills in the depth beneath you along the whole track, even if you were offline at the time. Review the track later on the map, see the seabed profile under your route, and keep a log of every trip. TAKE YOUR DATA WITH YOU Export tracks and seabed profiles as GPX or CSV files that open in chartplotters, mapping tools and spreadsheets. Depths are written the way chartplotters expect, so your recorded data slots straight into the rest of your navigation setup. TRUSTED SOURCES Depth data comes from EMODnet Bathymetry and GEBCO, the leading public bathymetric surveys. Depthly is a planning and reference tool: always use official charts and your own judgement for navigation. FREE TO USE, PRO IF YOU WANT MORE The free version includes five depth soundings every day, all map styles and unlimited track recording. Depthly Pro unlocks unlimited soundings, depth contours, seabed profiles, offline areas, GPX and CSV export and iCloud track sync. Pro is available as a monthly or annual subscription, or as a single lifetime purchase. The annual plan starts with a seven day free trial. Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period, and can be managed or cancelled in your App Store account settings at any time. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://blayasoft.com/privacy.html Drop a pin on the sea and know what is under it. Download Depthly and take your first sounding today.
Screenshots
Verdict
The clearest difference is in-app purchases: GPT at none against Depthly's 3. On price, ads, device support and iOS requirement 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
Both are free to download. Depthly sells 3 in-app purchases, starting at $3.99 per month. GPT asks for nothing beyond the download.
| Parameter | GPT | Depthly |
|---|---|---|
| Price | Free | Free |
| Positive reviews | 66.7% of reviews | — |
| Update frequency | Every 2 weeks | — |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.2 | 16.0 — better |
| Further details — not scored | ||
| Size | 51 MB | 23 MB |
| Age rating | 4+ | 4+ |
| Developer | Yu Lung WANG | Ivan Blajic |
In-app purchases
GPT
No in-app purchases
Depthly
- Monthly Premium$3.991 Month
- Annual Premium7 Days trial$8.991 Year
- Lifetime Premium$24.99







