Waypoints, Routes, and Routing Concepts
qtVlm uses three distinct objects — Routings, Routes, and Pathways — and understanding the difference is essential before you calculate your first weather route.
Points of Interest (POIs)
Everything in qtVlm starts with a position on the chart. Points of Interest (POIs) are how you mark specific locations — departure points, destinations, intermediate waypoints, hazards to avoid, or any position you want to reference later. They're the building blocks for all routing and navigation work.
Creating a POI is simple: right-click on the chart and select Create POI. A dialog appears where you can name the point, adjust the coordinates (the right-click position is pre-filled), and add notes. You can also enter coordinates directly if you have precise latitude/longitude values from a cruising guide or passage plan.
POIs persist between sessions — they're saved in qtVlm's internal database. You can import POIs from GPX files (the standard GPS exchange format), which means waypoints from your chartplotter, other navigation software, or online passage-planning resources can be brought directly into qtVlm. Similarly, you can export POIs to GPX for transfer to other devices.
Organize POIs into groups by right-clicking a POI and assigning it to a category. Common groups include 'Departure Points,' 'Destinations,' 'Hazards,' and 'Bolt Holes.' This keeps your chart uncluttered when you accumulate dozens of points over time.
Create POIs for your common departure and arrival ports. Having them pre-set saves time when you want to run a quick routing — you can select existing POIs as start and end points rather than clicking on the chart each time.
How do you create a Point of Interest in qtVlm?
Routings: The Weather-Optimized Calculation
A Routing in qtVlm is the raw output of the weather routing algorithm — a calculated optimal path from start to end that accounts for the GRIB forecast and your boat's polar diagram. It's the most important object in the software and the one you'll work with most.
A Routing is created through Routing → Create Routing (or by right-clicking and selecting the routing option). You specify a start point, an end point, a departure time, and the software uses the loaded GRIB data and polar to calculate the fastest route. The result is displayed as a colored line on the chart, often with isochrone fans showing the algorithm's expansion pattern.
Crucially, a Routing is a raw calculation — it may contain hundreds of tiny course changes, one at each algorithm time step. This makes it theoretically optimal but impractical to sail as-is. Nobody can steer a course that changes heading every 30 minutes. That's why the next step is converting the Routing to a Route (covered in the next lesson).
You can create multiple Routings with different departure times, different start/end points, or different settings, and compare them side by side on the chart. This is how you evaluate weather windows and departure timing — run the same route for several departure times and see which produces the shortest, safest, or most comfortable passage.
Think of a Routing as the algorithm's answer to 'what's the absolute best path?' It's a starting point for planning, not a finished product. The next steps — converting to a Route and simplifying — turn it into something you can actually sail.
Why can't you sail a Routing directly as-is?
Routes: The Simplified Sailing Track
A Route in qtVlm is a simplified, practical version of a Routing — a sequence of waypoints connected by straight-line legs that you can actually steer. Converting a Routing to a Route is the critical step that turns a theoretical calculation into a usable sailing plan.
After calculating a Routing, you convert it via Routing → Convert to Route. qtVlm creates a Route that follows the Routing's path but with far fewer waypoints — enough to capture the key course changes without the impractical granularity. You then simplify the Route further using Route → Simplify to reduce the number of waypoints to a practical level.
The simplification dialog offers two modes: Maximum simplification reduces waypoints to the absolute minimum while staying within a specified distance of the original Routing (useful for bluewater routes where 10-mile deviations don't matter), and Optimum simplification finds a balance between waypoint count and fidelity to the original path. After simplification, you can manually drag individual waypoints to fine-tune the Route.
Finally, you Optimize the Route via Route → Optimize Route, which recalculates the timing along the simplified path. This updates the ETA, leg durations, and expected conditions along each segment. The result is a Route with perhaps 6-12 waypoints that captures the essence of the weather-optimal path in a form you can actually navigate.
Always Optimize after Simplifying. Simplification changes the path, which changes the timing and conditions along the route. Without re-optimizing, the ETA and leg details are stale — based on the pre-simplification path. Optimize recalculates everything along the new, simplified path.
What does the Simplify function do to a Route?
Pathways: Constrained Route Sequences
A Pathway is a sequence of waypoints that the routing algorithm must pass through — forced intermediate points that constrain the route calculation. Pathways solve a common real-world problem: you know you need to pass through a specific channel, round a specific headland, or avoid a specific area, but you still want weather-optimized routing between those constraints.
Create a Pathway through Routing → Pathways → Create Pathway, then add waypoints in order. When you calculate a Routing with a Pathway attached, the algorithm finds the optimal weather route from start to waypoint 1, then from waypoint 1 to waypoint 2, and so on to the destination. Each leg is individually weather-optimized while respecting the mandatory passage points.
Pathways are essential for routes that pass through narrow channels, navigate around headlands, transit traffic separation schemes, or need to stop at intermediate ports. Without a Pathway, the routing algorithm treats the ocean as a free space and will route through land, across shipping lanes, or over shoals if the wind makes it faster. Pathways keep the algorithm honest.
The combination of Pathways with the routing algorithm is where qtVlm becomes truly powerful for real-world passage planning. A coastal route from San Francisco to Los Angeles, for example, might use a Pathway with waypoints at Point Reyes, Pigeon Point, Point Sur, and Point Conception — ensuring the route stays safely offshore at each headland while the algorithm optimizes the segments between them.
Don't over-constrain your Pathways. Each mandatory waypoint forces the router through that exact point, removing its ability to optimize around it. Use Pathways for genuine constraints (channels, headlands, separation schemes) and let the router find the best path between them.
When should you use a Pathway in qtVlm?
Summary
POIs are created by right-clicking the chart — they serve as start/end points for routing and can be imported/exported as GPX files.
A Routing is the raw weather-optimized calculation with hundreds of tiny course changes — theoretically optimal but impractical to sail directly.
A Route is a simplified, practical version of a Routing — converted, simplified (Maximum or Optimum), then optimized to update timing.
Pathways are mandatory waypoint sequences that constrain the routing algorithm — essential for coastal routes with channels, headlands, and narrow passages.
The three-object model (Routing → Route → Pathway) gives you both algorithmic optimization and real-world navigational constraints.
Key Terms
- POI
- Point of Interest — a named position on the chart used as a departure point, destination, or reference, created by right-clicking
- Routing
- The raw output of the weather routing algorithm — a theoretically optimal path with many fine course changes at each time step
- Route
- A simplified, practical version of a Routing — reduced to a manageable number of waypoints that can be steered and navigated
- Pathway
- A sequence of mandatory waypoints that the routing algorithm must pass through, constraining the route to follow a specific corridor
- Simplify
- The process of reducing a Route's waypoint count while staying within a specified distance of the original Routing path
- GPX
- GPS Exchange Format — a standard XML file format for exchanging waypoints, routes, and tracks between navigation software and devices