Balto/Graham Tools

Graham Tools

The Graham Tools calculator

The Graham Tools provide search planning calculators based on the methods developed by Hatch Graham in his paper "How Long Is Your Shadow?" for canine search and rescue operations. They help handlers estimate scenting conditions, plan grid spacing for area searches, and compute coverage rates. The Probability of Detection values presented here are based on research so as to be able to tell search planners what might be expected. In a training use-case, you can use the tools to determine how long it might take to cover an area similar to what you might encounter during a certification test.

Opening the Graham Tools

1. Tap the Options menu in the toolbar
2. Select Graham Tools
3. The Graham Calculator screen will appear

The screen contains four sections that work together to plan an area search.

Section 1: Scenting Conditions

This section computes the estimated Probability of Detection (POD) based on the current conditions where the search will take place.

Location

Enter UTM coordinates for the search location in the format "12S 0379774E 3821798N", or tap the GPS button to use your current location. Balto validates the UTM format and shows red text if the format is invalid.

Date and Time

Enter the date and time for the search in YYYY-MM-DD hh:mm format, or tap the Now button to use the current time. This is used along with the location to compute the sun angle and shadow length.

Shadow Length

Balto automatically computes the expected shadow length in feet based on the location and time. This serves as a quick visual check — you can compare against an actual shadow you measure on a 6-foot stick to verify your inputs.

Check the Night box if the search is at night or in deep shade, which significantly affects scenting conditions.

Surface Type

Select the dominant ground cover from the dropdown. This adjusts wind speed based on the vegetation in the area.

Get Current Weather

Tap this button to fetch current weather conditions from the internet (when available) for the location coordinates. After the weather is fetched, a dialog displays temperature, humidity, wind speed and direction, and cloud cover at different altitudes. The wind speed and cloud cover dropdowns are automatically populated based on the weather data.

Wind Speed and Cloud Cover

These dropdowns are automatically set by Get Current Weather but can also be set manually. They feed into the POD calculation.

Estimated POD

Displays the estimated Probability of Detection at 100 meters based on the current conditions. This represents the percentage chance that a dog will detect a subject when working at 100m spacing.

Cumulative POD at Distances

A grid showing cumulative POD at decreasing grid spacings: 100m, 75m, 50m, 25m, and 12.5m. As grid spacing decreases (more thorough coverage), POD increases. Use this table to choose a grid spacing that meets your target detection probability.

Section 2: Required Grid Spacing for Target POD

This section calculates the grid spacing needed to achieve a target Probability of Detection.

Target POD

Set the target POD percentage using the slider or text field. Typically you'd choose a value that matches your mission requirements (e.g. 70%, 80%, or 90%).

Grid Spacing Result

Balto displays the required grid spacing in meters and in paces (based on your configured pace count in Settings). Use this spacing when planning your search lanes.

Section 3: Grid Area Time Calculator

This section helps you understand the relationship between acres covered, hours spent, walking speed, and grid spacing.

Acres

Set the area to be searched in acres using the slider or text field. Range is 1 to 200 acres.

Time (hours)

Set the time available for the search using the slider or text field. Range is 0.1 to 4.0 hours.

Speed (mph)

Set the realistic walking speed for the search terrain using the slider or text field. Range is 0.5 to 3.0 mph.

Grid Spacing Result

Balto calculates the grid spacing in meters (and paces) that fits within these constraints. If the spacing is too small for adequate POD, you'll need to either increase available time, increase walking speed, or reduce the area.

Using the Speed Monitor

The realistic speed value can be measured in the field using the Speed Monitor feature. Walk a typical section of the search area and use the average speed reading.

Section 4: Acres Per Hour

This section computes search productivity given speed and grid spacing.

Speed (mph)

Set the walking speed using the slider or text field.

Grid Spacing (m)

Set the grid spacing using the slider or text field.

Acres Per Hour Result

Balto displays the acres covered per hour for the given speed and spacing. Use this to estimate how long a search will take given the area and desired coverage.

Tips

• Run Get Current Weather just before the search to use the most accurate conditions in your POD calculations
• The pace count used for converting grid spacing to paces is set in Settings under Handler Information
• Save your scenting condition assessment as part of the exercise notes so you can reference it later when reviewing logs
• For best results in the field, set up your Section 1 inputs at the start of training, then use the other sections to plan specific exercises