JP 3-50 National Search and Rescue Manual Vol I - US Navy

B. General Operational Considerations
1. Speed must be maintained to cope with sea conditions. While
small boats usually search at under 15 knots, hovercraft
search at 30 to 80 knots, and large vessels search at 10 to 30
knots. Vessels will be unable to maintain such speeds in
rough seas. High speed in some cases will affect SRU
stability.
2. Radius of action is determined by SRU ability to proceed to
the scene, remain on scene as long as required, and return to
base with sufficient fuel reserve. Small boat endurance is
limited to about 10 hours, SAR patrol boat duration is
normally a maximum of 100 hours, and SAR vessel duration can
be 30 days or more.
3. Maneuverability is essential for SAR operations in crowded
harbors, near irregular shorelines, and in high-density
surface traffic areas.
4. Seaworthiness, the ability to operate in adverse sea
conditions, is important. Generally, larger SRUs have the
better seaworthiness, seakeeping qualities, and weather/sea
penetration capability. As sea conditions become more
extreme, an SRU must decrease speed to reduce pounding and
crew fatigue, and may be unable to maintain a desired course.
SAR boats are usually limited to 4-foot seas and 25-knot
winds, while larger boats can operate in more extreme wind and
sea conditions.
5. Depth of water in which a vessel can safely operate must be
compared with the depth of water at the scene of distress.
The average draft of a SAR boat is 4 to 6 feet, with some only
1 foot; a SAR patrol boat, 6 to 12 feet; a medium-size SAR
vessel, 12 to 16 feet; large SAR vessels, 16 to 25 feet.
Supertankers and other deep draft vessels may draw 80 feet or
more.
6. Lookout capability is determined by SRU
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