1st vs Sea Depth
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
1st
Control your boat's engine and security features remotely. Receive man overboard alerts and manage access for others. Enhances safety and security for boaters.
- Theft Deterrent control
- Man Over Board alerts
- Time-limited access granting
- Proximity-based engine disabling
- Emergency contact notifications
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The 1st Mate app puts you in control of your vessel by interacting seamlessly with the 1st Mate system installed. You can easily control Theft Deterrent features, see Man Over Board alerts and give time limited access to your loved ones, or even the service guy. 1st Mate from Mercury and Quicksilver is the world's first engine-integrated man overboard and proximity-based theft deterrent system. Utilizing a highly styled wearable for up to 8 people, 1st Mate turns the engine off or sounds an alarm during a man overboard event (MOB), and optionally sends notifications to emergency contacts. If the proximity of the fob is not in range, the system disables or puts engine in guardian mode. All these functions are covering boaters most important needs, namely safety and security.
Sea Depth
Visualize detailed underwater terrain with high-resolution bathymetric charts. Gain deeper insights into seafloor structure, contours, and terrain for offshore activities. Includes optional data overlays and waypoint management for enhanced situational awareness.
- High-resolution shaded-relief bathymetry
- Detailed depth contours with intelligent labeling
- Optional data overlays (pipelines, bottom composition)
- GPX waypoint import/export
- Drift Test tool
- Offline chart access
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SeaDepth delivers professional-grade bathymetric charts for anglers looking to add a new level of detail and insight offshore. Built using high-resolution survey data and advanced shaded-relief techniques, SeaDepth reveals underwater structure, contours, and terrain that traditional charts often fail to show. The result is a clearer, more intuitive view of the seafloor - helping anglers and captains better understand offshore environments before and during time on the water. In addition to detailed depth visualization, SeaDepth offers optional data overlays, intelligent contour labeling, waypoint interoperability, and analytical tools that enhance situational awareness offshore. Key Features • High-resolution shaded-relief bathymetry • Detailed, clearly labeled depth contours • Intelligent contour interval scaling by depth range • Pipeline overlay (Gulf of America) • Bottom composition overlays highlighting seafloor characteristics • GPX waypoint import and export for interoperability with other platforms • Drift Test tool to observe drift direction and speed over time • Offline chart access for use beyond cellular coverage • Smooth zooming and panning optimized for offshore use Depth Contours with Intelligent Labeling SeaDepth uses a graduated contour labeling scheme designed to provide maximum detail where it matters most, while maintaining clarity and performance in deeper depths: • 1-foot contour intervals from 1 to 500 feet • 10-foot contour intervals from 500 to 2,500 feet • 80-foot contour intervals from 2,500 feet to abyssal depths This approach delivers high-resolution insight in shallow and mid-depth areas while avoiding visual clutter in deepwater environments. Overlay Intelligence SeaDepth allows users to enable optional overlay layers such as pipelines and bottom composition data in supported regions, including the Gulf of America. These overlays provide additional context and help users interpret bottom features and structural edges with greater confidence. All available overlay layers are included at no additional charge. Waypoint Management (GPX Support) SeaDepth supports importing and exporting waypoints using the GPX file format, making it easy to move data between SeaDepth and other compatible marine devices, charting software, or planning tools. This allows users to maintain consistent waypoint libraries across platforms. SeaDrift-Drift Test Feature The built-in Drift Test feature helps users evaluate drift behavior by tracking movement over time. This is especially useful when assessing current and wind influence to have more productive drifts. Built for Offshore Reliability Charts, overlays, and waypoint data are stored locally on the device, allowing SeaDepth to function reliably offshore where connectivity may be limited or unavailable. Performance and usability are optimized for real-world offshore conditions. Disclaimer SeaDepth is intended as a supplemental planning and visualization tool only. It is not a substitute for official nautical charts, onboard navigation systems, or prudent seamanship. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is rating: 1st at 5.0 against Sea Depth's 4.4. 1st also leads on in-app purchases (none vs 10). Sea Depth's advantage is update cadence (every 5 days vs monthly). On price, review sentiment, ratings volume and ads 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. Sea Depth sells 10 in-app purchases, starting at $99.99 per year. 1st asks for nothing beyond the download.
1st holds the better App Store score, 5.0 against 4.4. Both are backed by a comparable volume of ratings — 10 and 14 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
1st ships an update monthly, Sea Depth every 5 days. The most recent releases landed on October 6, 2026 and October 18, 2026 respectively.
| Parameter | 1st | Sea Depth |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (10 ratings) — better | 4.4 (14 ratings) |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 10 | 14 — better |
| Update frequency | Monthly | Every 5 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 15.0 | 15.0 |
| Further details — not scored | ||
| Size | 124 MB | 106 MB |
| Age rating | 4+ | 4+ |
| Developer | Mercury Marine LLC | Seadepth Charts, LLC |
Customer experience
1st
Sea Depth
In-app purchases
1st
No in-app purchases
Sea Depth
- Premium Charts Access7 Days trial$99.991 Year
- Western GOA 50%$150.00
- Eastern GOA 30%$209.99
- Cental GOA 20%$239.99
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- Eastern GOA 20%$239.99
- Cental GOA$300.00
- Western GOA$300.00
- Eastern GOA$300.00
- Florida-West Coast$300.00
- South Florida/Northern Bahamas$300.00








