What are different search patterns as per IAMSAR ?

Different search patterns:

EXPANDING SQUARE SEARCH

• Most effective when the location of the search object is known within relatively close limits.
• The commence search point is always the datum position.
• Often appropriate for vessels or small boats to use when searching for persons in the water or other search objects with little or no leeway.
• Due to the small area involved, this procedure must not be used simultaneously by multiple aircraft at similar altitudes or by multiple vessels.
• Accurate navigation is required; the first leg is usually oriented directly into the wind to minimize navigational errors.
• It is difficult for fixed-wing aircraft to fly legs close to datum if 5 is less than 2 NM.