Crab,
The US Coast Guard sent pilots and other ranks to Lakehurst, New Jersey for Blimp Training in 1945....so yes...SAR can be done by other than a helicopter.
During WWII....the US Navy used Blimps for SAR and other duties.....the K Model had a 59 hour Fuel Endurance and carried Radar.
https://books.google.com/books?id=q9...%20sea&f=false