Passive Underwater Fire Control Feasibility System

USS Harder (SS-568) with the three distinctive shark-fin PUFFS domes

Fin and central section of HMAS Onslow. The three orange covers on the casing are protective sheathes over the submarine's Micropuffs sonar

Passive Underwater Fire Control Feasibility System (or Study) (PUFFS) was a passive sonar system for submarines. It was designated AN/BQG-4 and was primarily equipped on United States Navy conventional submarines converted to GUPPY III or otherwise modernized in the 1960s. It was also equipped on the nuclear-powered USS Tullibee (SSN-597). A version known as "Micropuffs" was fitted on Oberon-class submarines for the Royal Australian Navy, and as Type 2041 on Upholder/Victoria-class submarines for the British Royal Navy. This class still serves in the Royal Canadian Navy, where Micropuffs is known as BQG-501.^[1] The system was notable for three tall, fin-like domes topside, except on Micropuffs installations. The system was retained on several submarines transferred to foreign navies. It was associated with long-range passive detection of targets for the Mark 45 nuclear torpedo and other torpedoes as well. Most submarines backfitted with it were also lengthened 12-16 feet to accommodate additional electronics and plotting rooms. It was also planned for Thresher and Sturgeon-class nuclear submarines, but was not fitted on them except Micropuffs experimentally on Barb and Haddock.^[2] With the exception of the four Canadian Upholder/Victoria class submarines, all PUFFS-equipped submarines have been disposed of or preserved as museum ships.

See also

• Greater Underwater Propulsion Power Program (GUPPY)

References

• Alden, John D., Commander (USN Ret) (1979). The Fleet Submarine in the U.S. Navy: A Design and Construction History. London: Arms and Armour Press. ISBN 0-85368-203-8. 
• Sub vs Sub, Cdr R Compton Hall, Orion Books, 1989