1.5  Define the Parameters for the Search

Each mission will require an analysis of the requirements and determination of the appropriate settings to use during the search to achieve the objectives.

The following settings are recommended for a drowning victim search (assuming a 1.8 m (6 ft) person) and are based on the experiences accumulated during a number of successful recoveries. Searches for other size objects or area clearing or mapping may require different settings to optimize the chances for success in those situations.

• Sonar range: 18 m (60 ft) ~ 10 X object size
• Camera angle: ~ 5 - 10 degrees down
• Vehicle pitch: ~ 5 - 10 degrees nose down
• Define pattern perimeter: as determined by confidence in the information about point last seen and local geography and water conditions (still water of swift current)
• Define pattern orientation: Traversing longer pattern transects is generally better than shorter ones. Some consideration should be given to the launch point relative to the pattern, but the mission can be navigated through the pattern in either direction.
• Define transect spacing: 18 m (60 ft) ~ the sonar range, allowing approximately 25% overlap.
  This recommendation is based on using a wide angle sonar with a horizontal beam angle of 120 - 130 degrees. If using a high frequency sonar with a horizontal beam angle of 45 degrees, the recommended transect spacing should be reduced to about 35% of the sonar range to maintain adequate coverage.

These settings can be made during the steps that follow for setting the Waypoint Defaults, Placing a Region and Setting the Coverage.

The above guidelines are recommended starting points and can be modified as appropriate for the operation.

The region size and shape is defined by the user.

Project Type	Recommendation
Wide Area Search	The region should be centered on the best information available for the location of the object. The less certainty of the object's location, the larger the search area may need to be.
Clearing or Mapping an Area	Defined by the perimeter of the area to be cleared or mapped.

For very large search areas, the area can be broken down into smaller overlapping regions.