Optional "Course Solution Function is Unique to Force 4

Using the Force 4 "Solve Course" Function to Analyze and Compare Defined Courses
Force 4 provides a UNIQUE function called "Solve Course." This looks at each leg and computes the distance (range) and a heading which corrects for currents along the way. The result also gives time for the leg, arrival time at each waypoint and totals for distance and time for the entire course.

This computation depends on the assumed speed of the boat, for which there are two options: (1) assume a fixed speed over the water (motorboat solution); or (2) estimate speed for each leg by calculating the angle to the wind (TWA) and using the boat's performance characteristics (polars). You can fix boat speed (or wind speed and direction) for the entire course or leg by leg (see below). Or, you can use a wind model (grib file) to take into account wind variations in time and location.

Compared to a routing solution, the difference is that, with a router, the program computes an "optimal" solution to the destination; whereas with "Course Solution" you start with an idea for route, defined by a defined course or "quick" course, and test how long it will take, then compare this to another possibility. Force 4 saves the different solutions and you can recall and compare them on the same page.

You start with the form below. Make your selections and then click 'Apply' to begin the computation. To use a Wind Model, click the button for 'Use Wind Model' and pick a Model from the list that appears. To change the model, click on the text box to the right of that button to get the list.

courses6.gif (41935 bytes)
The solution for a course appears as shown below, giving details for each leg and totals for the entire course. All solutions for a given day are saved in a text file coded with that date (shown in title bar of solution form). You also save this particular solution to a file of your choice and/or print it, using the buttons at the bottom of the form. Click 'List Marks' to see the list of marks (waypoints) and their coordinates. Click 'Summary' to see total time and distance for all courses computed that day. This is a good way to compare time and distance for alternative courses, or different assumptions about starting time and wind conditions.
courses7.gif (29383 bytes)
If you click the button to 'Set Boat/Wind Values on Each Leg' you will see the form below (assuming fixed wind input, otherwise the form just asks for boat speed on each leg). With a wind model, continuous wind adjustments are calculated.
courses8.gif (40953 bytes)

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