October 23, 2025 | Development Update

Have you ever started a voyage, anchored overnight due to weather, and then wanted to continue your passage plan from where you left off? Or maybe you closed the app mid-voyage and wanted to pick up your route from your current position? We’ve just added features to Mariner Studio that make this scenario not only possible, but incredibly simple.

The Problem: Rigid Route Planning

Traditional marine voyage planning tools have a limitation: routes always start from waypoint 1. This works great for a fresh departure, but real-world cruising is rarely that straightforward. Weather windows change, crews need rest, and sometimes you just need to anchor for the night and continue the next day.

Previously, if you were at waypoint 7 of a 63-waypoint passage and wanted to recalculate your ETAs (Estimated Times of Arrival) from your current position, you’d have to either manually work through the math or create an entirely new route starting from waypoint 7.

The Solution: Start From Any Waypoint

We’ve just completed a major enhancement to the Voyage Plan feature that gives you complete flexibility:

1. Choose Your Starting Waypoint

The voyage planning interface now includes a “Starting Waypoint” selector. Simply tap the dropdown and choose any waypoint along your route as your starting point. The system will calculate ETAs, weather conditions, and marine forecasts for all subsequent waypoints based on your selected starting position, departure time, and average speed.

This is perfect for:

• Multi-day passages where you anchor overnight
• Weather delays that require recalculating your arrival times
• Crew changes where you’re joining a vessel mid-passage
• Replanning after diversions or course changes

2. Auto-Detect Your Position with “Current Location”

Here’s where it gets really smart: we’ve added a “📍 Current Location” option to the starting waypoint selector. When you choose this option and tap “Calculate ETAs,” Mariner Studio uses your device’s GPS to automatically determine which waypoint you’re closest to and starts the voyage plan from there.

The app calculates the distance to every waypoint on your route using precise haversine formula calculations (accounting for Earth’s curvature) and selects the nearest one. You’ll see exactly which waypoint was chosen and the distance to it in nautical miles.

This feature is invaluable when:

• You’ve deviated from your planned route and want to rejoin it
• You’re picking up a saved route from a previous trip
• You want to start from the most convenient waypoint without manually checking distances

Technical Details for the Navigation Nerds

For those interested in the technical implementation:

• Distance Calculations: We use the haversine formula with Earth’s radius of 3,440.065 nautical miles for precise distance measurements
• ETA Calculations: The system calculates bearing and distance between each waypoint, then computes arrival times based on your average speed
• Weather Integration: Each waypoint’s ETA is used to fetch marine weather forecasts for that specific time and location
• GPS Integration: Leverages Core Location framework for accurate positioning

The route details view now shows only the waypoints from your selected starting point forward, keeping the interface clean and relevant to your actual voyage.

Real-World Example

Imagine you’re sailing from New York Harbor to Boston (63 waypoints). You depart on schedule but encounter fog at waypoint 6 near Block Island. You anchor overnight. The next morning, instead of creating a new route or calculating manually, you simply:

1. Open your saved “NY to Boston” voyage plan
2. Select “📍 Current Location” from the Starting Waypoint dropdown (or manually select waypoint 7)
3. Update your departure time to this morning’s time
4. Tap “Calculate ETAs”

Instantly, you have fresh ETAs for all remaining waypoints, along with updated weather and marine forecasts for each position based on your new arrival times.

We Build What You Need

This feature enhancement came directly from thinking about real-world cruising scenarios. If you have ideas for features that would make Mariner Studio more useful for your specific needs, don’t hesitate to reach out. We’re actively developing this app and responsive to user feedback. Your insights from the water are invaluable.

The voyage planning tool now gives you the flexibility to handle the realities of cruising: weather delays, overnight anchorages, and course changes. Because the best navigation app isn’t the one with the most features—it’s the one that adapts to how you actually sail.

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Mariner Studio is available for iOS and Android and includes comprehensive marine forecasting, tidal predictions, current station data, and advanced voyage planning tools. The app integrates with NOAA data sources to provide accurate, real-time marine weather information for North American coastal waters.

Have feedback or feature requests? Contact us at [email protected]

Keywords: marine voyage planning, GPS waypoint navigation, sailing route planning, marine weather forecasting, ETA calculator, coastal navigation app, cruising tools, passage planning software