Useful tool for Inshore regatta
Routing on Coastal Course is not a function that may come to mind during Inshore regatta. And yet, it helps a lot!
Here are a few keys in order to use it as a tool of anticipation and a precious help in tactics at sea.
2 requirements are mandatory before launching a routing calculation on Courses:
1/ Create a course
Tutorial to create courses in ADRENA available here.
Spi Ouest France 2015 competitors can download all WP and Courses here.
2/ Collect weather forecast data
For inshore racing, it is necessary to get weather forecast data as accurate as possible in order to make the most of the routing. 4 suppliers are integrated in ADRENA navigation software:
- Navimail: data available for a fee but very precise on the coasts: GRIB at 0.25°
- Predictwind: high resolution data available for a fee: precise GRIBS of 1km and 8km available on some areas
- Squid : high resolution data available for a fee (CEP, GCWF)
Some models of these suppliers take into account local sea breeze as well as coastal effects and are well known for their tremendous accuracy and reliability.
- NOAA : Free weather forecast worldwide: GRIB at 0.25°
Launch the routing before the race:
Departure-Destination Tab:
The “Course” button enables to choose among the courses already created the one to use for the routing. The software displays the list of waypoints belonging to the course so that you can select the 1st waypoint to go through.
NB : During the creation of a course, it is important to indicate which marks are left out so that the software can calculate the most direct trajectory.
Calculation Settings Tab
In a coastal routing, segments between two waypoints can be quite short and currents influence more important. As a consequence, it is better to reduce the isochrones duration in order to obtain a more accurate routing.
E.g.: On the above picture, the routing in blue with a step of 90 min and the routing in green with a step of 20 min present a difference of 26 min on the finishing line.
Warning: reducing the isochrones duration involves an extension of the calculation delay.
Gribs-Wind Tab
Select one or several GRIB files that you have already loaded.
Additional fields enable to load waves or winds GRIB files. If you have currents GRIB files, load them in “Forecast? Currents? Load currents GRIB”.
It can be interesting to use several wind GRIB files during the same routing: for example, when we have more precise GRIB near the coasts and more general GRIB offshore. In this case, route calculation favors the following elements in this order:
- Most precise GRIB (geographical resolution)
- GRIB in which the time step is the shortest
- Most recent GRIB
- GRIB from the highest rank in the list
Example of a difference of resolution between two GRIB files (fine mesh in blue and large mesh in green).
Trick:In a coastal routing, it is interesting to force the wind in strength and direction in order to assess the currents influence. The button in the option “Constant Wind” enables to force the wind measured by the CPU.
Relaunch the routing in a race:
In this case, the boat sailed past too far from the portside mark (WP30). Thus, the navigator validated the WP31 waypoint manually thanks to the button .
Then, the routing is relaunched by using the current time (“Now” button) and the current boat’s position as the starting point (“Here” button). In the course, we have to select next waypoint for the routing (in this case: WP31).
Gribs-Wind Tab
When sailing, if you notice that the wind conditions are not in line with the predictions, it is possible to force the wind or to verge on the GRIB.
The “Go to GRIB from” enables to force the wind at the beginning of the routing and to “glide” gradually towards the GRIB predictions.
To do so, tick the box “Go to GRIB from” then click on in order to get the wind back directly from the CPU. Then, indicate the length of time in which you want the current wind conditions to move towards the predicted ones.
At the beginning of the routing, the wind will be the one that you have forced. After the specified length of time, the wind will be the GRIB one. In between, the wind will move gradually from the forced wind to the GRIB wind (in speed and direction).
For offshore or inshore regattas, ADRENA gives the opportunity to anticipate new situations and supplies appropriate tools in order to adapt and update routing to the real regatta conditions.
