Professional Weather Routing
What is a Professional Weather Routing is ?
Routing functions are only available the software is configurated as professional version and have the
PERFORMANCE OR ROUTING modules.
Routing is the calculation of the optimum course. The two most important factors involved in achieving the optimum course are the weather forecast and speed of the sailboat. Other influences include tidal and ocean currents that may cause the boat to drift significantly, depending upon the strength of the current.
MaxSea offers "true routing", which uses an algorithmic method to determine the optimum route
The program incorporates routing functions that which allow you to calculate the optimum course for your yacht given the forecasted conditions.
Note: the Routing functions are to be found under the [Performance] menu.
What is a Professional Weather Routing is ?
Routing functions are only available the software is configurated as professional version and have the
PERFORMANCE OR ROUTING modules.
Routing is the calculation of the optimum course. The two most important factors involved in achieving the optimum course are the weather forecast and speed of the sailboat. Other influences include tidal and ocean currents that may cause the boat to drift significantly, depending upon the strength of the current.
MaxSea offers "true routing", which uses an algorithmic method to determine the optimum route
The program incorporates routing functions that which allow you to calculate the optimum course for your yacht given the forecasted conditions.
Note: the Routing functions are to be found under the [Performance] menu.
Before Calculating a Professional Weather Routing
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To use the Routing function you must do the following:
1 - Opening a polar file
Your ship’s potential performances are saved as speed polars. Contact your MaxSea distributor for information on how to obtain polars for your particular boat.
The first time the program is launched, you are asked to select a polar file; this is the file that will loaded automatically each time MaxSea is started.
•If you wish to change the polar file select [Open Polar Curves File] from the [Performance] menu.
•Select the desired file from the list and click on Open.
2 - Opening a weather file
see entitled Weather module to learn how to manage weather files.
You should select a weather file which covers both the start-point for the routing (the ship’s present position) and the desired course.
The start date for the routing must also fall within the dates covered by the weather file.
If the weather dates are outside the current date, a dialog box appears and warns you that the present route plan will start precisely at the first weather file's date.
In the case the start waypoint is situated outside the geographic zone covered by the weather file two possibilities:
1.The start waypoint is too far from the last weather file point. A dialog box appears and warns you that the last waypoint is outside the geographic zone weather file. The routing can not be launched at this time.
2.The start waypoint is situated in an interval close enough to the last available weather file point.
The routing is launched from an interpolation of the nearest weather data. The interpolation interval data depends of the weather file data precision.
The following example shows you how the interpolation calculation is done:
In case the distance between two data points from the weather data file is equal in 50M, the interpolation calculation will be done on the last available weather data. The values will decrease since this last value (10 N from the following example) until 0 N.
In the case the arrival waypoint is situated outside the geographic zone covered by the weather file:
Professional Weather Routing
At this moment the routing will stop at the end of weather file data.
In the case the arrival waypoint is situated outside the weather file's data:
The Route plan will reach to the target waypoint and a label is displayed on the chart which indicates the end of weather file's data. The isochron curves will be drawn in different colors to show the difference.
3 - Displaying tidal current
Display and activate the Tidal current layer on the chart if needed (by clicking on Tidal Current
button, select Active Current Data and choose which Tidal Current layer you want to add in your routing calculation ).
4 - Choosing the course start-point
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This is your yacht’s present position, so nothing needs to be done here.
Note: it is possible to display your competitor’s yacht as well as your own (refer to the next paragraph, Launching a competitor’s routing ).
5 - Choosing a target waypoint or several waypoints ( MaxSea allows routing on several waypoints)
Plot a waypoint or several waypoints on the chart (refer you to the "Active Route" chapter for more information)
Calculating a Route
Once you have plotted an active route and opened the corresponding files , select the [Calculate Routing] from the [Performance] menu.
A dialog box appears and allows you to configure the Routing parameters (refer to the next paragraph Modifying routing parameters ).
By default the Routing parameters are the following:
Study angle : -60 to 60°
Number of isochrons to display : 60
Isochron interval : 2 hours
Efficiency : 100%
Displaying Pro Routing on the Chart
The routing’s startand finish-points, together with its start-date, will be displayed as well as some additional parameters which can be modified in the different input texts (refer you to the following "Modifying routing parameters" paragraph).
Then Click on OK to validate the parameters shown and launch the routing.
Isochrons will be displayed on the chart and note that you can interrupt the display of isochrons at any point by clicking the mouse button.
Professional Weather Routing
Once the last isochron has been drawn (the total number having been determined in the routing parameters, as outlined in the next paragraph Modifying routing parameters to change it), the program calculates the optimum course for reaching or getting nearer to the selected waypoint .
From a waypoint
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Isochrons are displayed on the |
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chart as alternate yellow and |
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purple curves. Each numbered |
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isochron is drawn every 2 hours |
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(this parameter value is defined by |
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default) on the chart (yellow |
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drawing lines) and in the case the |
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routing is calculated on several |
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days the date is displayed for each |
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24 hours on the chart (purple |
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drawing lines). |
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All route plans indicated by |
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isochrons are optimal route plans |
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(drawing in black); they simply |
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show route plans in accordance |
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with varying criteria ( bearing more |
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to the north, more to the south, etc.) |
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and thus with varying proximities to |
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the target waypoint. |
• |
Once the last isochron has been |
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drawn the program calculates the |
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optimum route plan (drawing in |
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red) for reaching the selected |
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waypoint. |
From several waypoints (multi-waypoint routing)
If you have plotted several waypoints on the chart and launched the Routing.
The multi-waypoint routing allows to define an optimal route plan of from the boat position to the active waypoint then from this waypoint to the following waypoint and so till the end of the course.
In this case the arrival waypoint is situated outside the weather file's data:
At this moment the Route plan reaches to the target waypoint and a label is displayed on the chart which indicates the end of weather file's data. The isochron curves are drawn in different colors make the difference.( the yellow color becomes a green color) to
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The routing is calculated by the program using a set of extremely powerful algorithms. It allows you to display the general options. It also takes into account any current file which is subsequently opened (tide or ocean current).
The form of the displayed isochrons is particularly important for an overall evaluation of both options and risk. For example, an isochron which is swollen in the north and fleeing in the south means that options in the north are generally favorable; an isochron with a pronounced tip indicates a very favorable course, but one which must be followed strictly (thus having a high risk factor); a flat form, on the other hand, indicates that the chosen route is not particularly favorable.
These elements can all be taken into account when deciding on tactics (with regards to other competitors) as you can chose both where to position the yacht in comparison with the optimum route and the risk to be taken, for example by noting the position of a competitor (refer to the next paragraph, Optimal routing ).
Notes:
1 - it is possible to display your competitor’s yacht as well as your own (refer to the next paragraph, Launching a competitor’s routing ).
2 - to calculate the routing, the program uses the polar which is currently active. However, you can choose to use another polar file and re-launch the routing. (Related topic: Opening a polar in the performance module chapter).
3 - isochrons can be displayed or hidden in order to improve the legibility of the chart; click on [isochrons] to check the option and click again to uncheck the option , as appropriate, from the [Performance] menu.
Professional Weather Routing
4 - all courses indicated by isochrons are optimal courses; they simply show courses in accordance with varying criteria (bearing more to the north, more to the south, etc.) and thus with varying proximities to the target waypoint.
If a routing has been plotted and you then decide to launch a second routing (once you have changed the weather file or opened a different polar, or to plot the course of one or more competitors, etc.), the program saves a track in the User file which corresponds to the initial routing and which contains all its parameters (times at certain points in the passage, wind force and direction, etc.). sees User data and High level functions for the management of such data (for example, how to remove a track) and access information at any point on the plotted course (by double-clicking at the desired point with the Finger tool).
Initializing Weather Routing
To access to the modifying routing parameters select the [Calculate Routing] function from the
[Performance] menu
The Initialization Dialog is displayed and allows you to enter the desired parameters in the corresponding input texts.
1 - Position and Date zone: allows you to change the date study
2 - Graph zone allows you to define your graph Depending on :
The Angle Study : Routing is carried out either side of the great circle; you can specify, to the nearest 10°, the minimum angle (to be shown as a negative figure to the left of the great circle) and the maximum angle (a positive figure to the right of the great circle). Values of -60° and +60° are adequate in most cases (default value.)
Isochron Number :The program will display the number of isochrons specified in accordance with steps entered in the routing parameters. The length (in time) of the study you are going to make will be equal (in hours) to the number of steps multiplied by the interval between isochrons (see the next paragraph).
Interval between Isochrons: The time interval specified dictates the level of accuracy of your study; a value which is half the value specified for time intervals in the weather file should be correct (4 or 6 hours in the case of typical files based on 12 hour intervals). The time interval is unlimited till the end of the weather file and the isochron interval can be reduced down to 1 minute. "00 d 02 h 00 mn"by default the interval number is equal to 2 hours. In very changeable weather conditions you may need to use a value which is a quarter of the one specified in the weather file in order to obtain a very precise study.
Efficiency: The efficiency can be modified to take into account speeds which are different from those contained in the speed polar (in the case of a sea which is particularly hard to navigate, problems with the sails, the crew being tired, equipment not working properly, etc.)
3 - Calculation Zone: allows you to choose which
Click on the OK button once you have made your modifications to launch the routing (see the previous paragraph Launching a routing ).
Customizing Routing
Show & Hide isochrons on the chart
Isochrons may be displayed and removed at your will in order to improve the legibility of the chart:
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simply choose [Display isochrons] from the [Performance] menu to show isochrons ( "Display isochrons" item is checked) or, as appropriate choose again this option to hide isochrons ( "Display isochrons" item is unchecked).
"Display isochrons" item selected |
"Display isochrons" item is |
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unselected) |
Plot a color to a route plan
Before launching a route plan select a color from the Toolbar and then launch a routing. The routing track will be drawn with the selected colors.
In this case Pink color was selected before launching a routing.
Delete a Route plan
To delete the optimal route plan and its corresponded isochrons, you have to simply hide the weather file by clicking on
the weather button 
, at this moment the program saves the track in the active Layer(PDF) file which corresponds to the initial routing and which contains all its parameters (times at certain points in the passage, wind force and direction, etc.).
