A family has purchased a property next to a golf hole. They want to be able to safely utilize their backyard, especially when children are playing. They asked how high to build nets along their property line so that their backyard is protected.
The owner provided the GPS location of their property along with the coordinates of the various tees that golfers would use. The owner also provided some photos of their property from the golf course along with views golfers would have lookin up the fairway.
In the above Google Earth image, the coloured lines mark the distances from the 3 different tees to the property in question.
Given the distances, golf shots are then simulated with various trajectories such as:
1. right swinger pulling shots that travel straight towards the property
2. right swinger hooks shots that start out down the fairway and curve left towards the property.
3. left swinger pushes shots that travel straight towards the property.
4. left swinger slices shots that start out down the fairway and curve left towards the property.
At the location of the property line (intersection of the 3 coloured lines in the image above), one calculates the height, speed and trajectory angle of the golf ball in order to determine the minimum net height required to prevent balls from entering the yard.
Below is a sample graph of the trajectories for different club swing speeds appropriate for the analysis.
Note that the vertical scale of the graph has been omitted. The vertical and horizontal scales are not the same.
The solid, black, vertical line represents a possible fence. The orange horizontal line represents the depth of the yard that requires protection. Note in this graph that 90 mph trajectories could clear the fence and land into the back of the yard. Thus, for such trajectories hit by this group of golfers, the net would need to be higher.
What can also be analyzed is the likely frequency of such shots.
One can calculate a containment percentage based on the height of the netting. Different heights would contain different percentages of shots.
25 yd height contains 90% of shots
30 yd height contains 95% of shots
35 yd height contains 98% of shots
See sample images below showing the scatter of Tees Shots and the scatter of iron shots to a green. These scatter diagrams are based on the most substantial amateur golfer data base available. One can calculate what percentage of shots will end up outside the "normal cone" of scatter.