https://peertube.dngr.us/videos/watch/3e656dce-dd01-4fbb-9f8a-5762e13b01ae Join this channel to get access to perks: https://www.youtube.com/channel/UCddem5RlB3bQe99wyY49g0g/join Help us preserve, scan and post more rare and endangered films! Join us on Patreon. Visit https://www.patreon.com/PeriscopeFilm Visit our website www.PeriscopeFilm.com 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. Motion picture films don't last forever; many have already been lost or destroyed. For almost two decades, we've worked to collect, scan and preserve the world as it was captured on 35mm, 16mm and 8mm movies -- including home movies, industrial films, and other non-fiction. If you have endangered films you'd like to have scanned, or wish to donate celluloid to Periscope Film so that we can share them with the world, we'd love to hear from you. Contact us via the weblink below. This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD, 2k and 4k. For more information visit http://www.PeriscopeFilm.com Source: https://www.youtube.com/watch?v=vEkhYcx0Ps4 Mirrored from Periscope Film (https://www.youtube.com/@PeriscopeFilm) Thu, 11 Jun 2026 06:24:34 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://peertube.dngr.us https://peertube.dngr.us/lazy-static/avatars/41a6fee9-7f57-42d0-a5fc-5db4f1af2e31.png https://peertube.dngr.us/videos/watch/3e656dce-dd01-4fbb-9f8a-5762e13b01ae All rights reserved, unless otherwise specified in the terms specified at https://peertube.dngr.us/about and potential licenses granted by each content's rightholder.