[UNDERWATER DEMOLITION TEAM UDTs / U.S. NAVY SEALs SWIMMER PROPULSION UNITS SPUs ]

Description:

This rare, silent footage shows important early propulsion units and mobility inventions developed by U.S. Navy Underwater Demolition Teams or UDTs, now known as the U.S. Navy SEALs. The film likely dates to about 1952, although it could be slightly later. It begins with footage of UDTs operating an Aerojet underwater vehicle commonly known as a Swimmer Propulsion Unit or SPU (:14). At (:20) UDTs are seen on the exterior of the the WWII submarine USS Quillback (SS-424) as it surfaces. Quillback was a Tench-class boat used extensively by the UDTs for training, and was the first to conduct swimmer retrieval through a torpedo tube. At :30, rare footage of the Swimmer Propulsion Unit Mark II is shown. These SPUs featured propellers (the unit shown at 2:00 clearly has twin counter-rotating props) and had diving planes for airplane like maneuvers underwater. The Mark II was essentially a one-man sub was fitted with a CO2 propulsion system, in addition to the pedal-drive system. A steady-state speed of three knots for three miles could be achieved with the pedal-drive system. Using C02, the SPU was capable of four knots for 15 minutes. At 1:23, the Mark V Swimmer Propulsion Unit is shown. This was sort of like an underwater bicycle, with a pole and saddle connected to counter-rotating propellers driven by bicycle pedals and gears. A fixed speed and efficiency for the vehicle of four times that obtainable with swim fins was claimed. At 2:04, a Mark II and Mark V are shown operating in close proximity.

Complete Record: This rare, silent footage shows important early propulsion units and mobility inventions developed by U.S. Navy Underwater Demolition Teams or UDTs, now known as the U.S. Navy SEALs. The film likely dates to about 1952, although it could be slightly later. It begins with footage of UDTs operating an Aerojet underwater vehicle commonly known as a Swimmer Propulsion Unit or SPU (:14). At (:20) UDTs are seen on the exterior of the the WWII submarine USS Quillback (SS-424) as it surfaces. Quillback was a Tench-class boat used extensively by the UDTs for training, and was the first to conduct swimmer retrieval through a torpedo tube. At :30, rare footage of the Swimmer Propulsion Unit Mark II is shown. These SPUs featured propellers (the unit shown at 2:00 clearly has twin counter-rotating props) and had diving planes for airplane like maneuvers underwater. The Mark II was essentially a one-man sub was fitted with a CO2 propulsion system, in addition to the pedal-drive system. A steady-state speed of three knots for three miles could be achieved with the pedal-drive system. Using C02, the SPU was capable of four knots for 15 minutes. At 1:23, the Mark V Swimmer Propulsion Unit is shown. This was sort of like an underwater bicycle, with a pole and saddle connected to counter-rotating propellers driven by bicycle pedals and gears. A fixed speed and efficiency for the vehicle of four times that obtainable with swim fins was claimed. At 2:04, a Mark II and Mark V are shown operating in close proximity.