Friday, June 18, 2021

Sharing Routes Between OpenCPN and qtVlm

OpenCPN and qtVlm are the two most popular navigation programs in the world, with thousands of international users. They are free programs, both with options to make donations to help cover expenses and support the developers. They each have both PC and Mac versions, along with other options, including mobile versions.

Each has its own unique and powerful features, many of which we don't find elsewhere, or maybe only in high-end commercial products. Because they are both sound, working tools with unique strengths, we use both in our online navigation and weather training courses at Starpath. 

Common to both, of course, is the option for user-created routes made up of a sequence of waypoints. Essentially any navigation program, not just these two, include this operation in some form, which is indeed a requirement of the International Maritime Organization (IMO) for an approved navigation program. If you are not following a route, you are not navigating; you are just out sailing. And essentially all navigation programs offer a way to export a final route in the form of a GPX file, which can in turn be imported into other navigation programs.

But OpenCPN and qtVlm have jointly gone a step beyond this in that each includes the functionality to just copy a route from the chart screen and paste it onto the chart screen of the other program. The reason this is so valuable is tied to the way each program creates the routes. Each has specific strengths you may want to take advantage of for the route creation, even though you choose to navigate that route in the other program. 

qtVlm, for example, is oriented toward sailboat navigation under sail. It offers several fast, easy ways to create a sailing route based on the vessel's polar diagram and a loaded grib file of forecasted wind—tools that do not require running a full isochronal routing computation. But those tools are not a bonus when you know you must be under power for most of the voyage.

OpenCPN, on the other hand, offers more convenient waypoint placements and adjustments, with quick chart display changes, so it offers a faster way to make a fine tuned route through a complex waterway that will be traversed under power.

Thus we may want to use one or the other programs for setting up our route, depending on the conditions, and then having the route in hand, we want to paste it into the other program.  In very broad terms, OpenCPN is likely best choice for complex routing under power and qtVlm is the best choice for figuring a route that must be followed mostly under sail.

In the common case of wanting to sail as much as possible, but knowing we have to go under power along parts of a complex route, maybe many days long, then we might want to create and fine tune the route in OpenCPN then paste it into qtVlm to see how much of it we might actually sail when we learn the actual wind forecasts when we are there.

Also, there are different protocols for following an activated route in the two programs, as well different simulation options, and different interactions with AIS targets. So even if we are set on actually using one over the other once underway, it could be we learn a lot about navigation of the route by simulating the following of the route in each of the programs.

Another example of cross program navigation, without even considering the distinctions between power and sail,  could be the choice to use OpenCPN for routine chart navigation to take advantage of its convenient interface of controls and chart display, while running qtVlm simultaneously to monitor and evaluate the weather along the route since it has so many powerful and unique weather related features. This type of operation greatly benefits from the ability to copy and paste a route from one to the other program.

So we are lucky that these two programs have collaborated to let us just right click a route, copy it, and then paste it into the other program, as if we had made it there.

And, while here, may I take the opportunity to thank the developers of both programs for the fine products they have made available to the public. This is a huge benefit to mariners worldwide. 

Later, individual mariners may choose one of the long-tested commercial products such as Expedition, Coastal Explorer, LuckGrib, and TimeZero. These products have earned their top of the line ranking. We use all of these ourselves in various applications, as do top navigators worldwide. But we cannot overlook the valuable role of the two free programs we discuss here for the introduction and training they provide mariners on the power of echart navigation.

Below is a video demonstration of the process.


Mihael said...

Sorry for my english.
qtvlm is a paid program for android.
25 years ago I was engaged in numerical weather forecast. / Then there was a perestroika ... / I know where are bugs. I found them. In the traditional place at the intersection of the main meridian. Instead of thanking me for testing, I know out that all has been tested 1000 times. Maybe I'm already old. But it always seemed to me that it is better to wash the previous than to give birth to new. Endlessly adding new sophisticated features to programs without fixing old bugs is a path to collapse. And there are examples of this.

David Burch said...

Mihael, very sorry to hear that you had troubles with qtVlm in the past, but I would guess that they have resolved these over these years, and indeed if any linger you can contact them at for prompt help. I agree with your basic sentiment about any software, but the sharing routes covered here is actually one of the very old features—it was just new to me. However, in my mind they have indeed made several extremely valuable new additions to the program over the past months, with several more on the horizon. We used, for example, the powerful new simulation options of qtVlm to investigate the grounding of the Ever Given in the Suez Canal ( ). If there are specific issues you can point to please let me know and we will have look. I hope to post a summary soon of the new features we find so valuable.