When voyagers far out at sea need rescue, they are usually out of range of helicopters and even fixed wing rescue aircraft, such as Coast Gaurd HC-130 Hercules turboprops. So for "on the scene" assistance, the Coast Guard relies on merchant vessels that pariticipate in the Automated Merchant Vessel Reporting system (AMVER). Ships that have voluntarily signed up for AMVER have agreed to render assistance to other vessels in distress, whether these vessels in trouble are commercial ships or cruising sailboats.
The Maritime Executive web site has an excellent interview with Captain James Kelleher, the master of the 893-ft. containership Horizon Reliance. On February 8, 2012, Kelleher and his crew, while en route from the West Coast to Hawaii, picked up three sailors from a sailboat in distress, one of which was a nine year old boy. Kelleher gives a detailed report of the rescue that is well worth reading.