TomDougherty Posted November 8, 2025 Report Posted November 8, 2025 Following WWII, the US had a large number of relatively new diesel fleet submarines. Although these were very successful in the Pacific War, the technology and development of the German Type XXI U-boats pointed to a future in which more capabilities would be necessary. The US Navy embarked on a program to modify and upgrade some of the newer fleet submarines. The overall program was termed Guppy (Greater Underwater Propulsion Program, with the Y added). This meant streamlining the submarines by removing deck guns and adding a "step sail" in early conversions, upgrading batteries (and in some of the modifications such as Guppy II, doubling the battery cells) and adding a snorkel. The snorkel meant that the diesels could be run while submerged, recharging the batteries. These conversions (Guppy I, Ia and II) were carried out in the 1950's. With a lag in nuclear attack submarine building in the early 1960's, a small number of Guppy II submarines were selected for a further upgrade, termed Guppy III. These submarines already had the doubling of battery cells, and as an initial step, a new sail, termed the High Atlantic sail was fitted. This was an improvement on the earlier "step sails" which had the bridge watch crew at a lower level (see my earlier build of Becuna on this forum). In Atlantic storms, crews on the step sail would get soaked with cold water from waves coming over the bow. The Atlantic sail got the watch crew up higher off the deck. In addition, the submarines were cut apart forward of the sail, and a 15 foot long "plug" was added to create space for a dedicated sonar room. Also added was the BQG-4 PUFFS passive ranging sonar, which are the three "fins" on the deck. With PUFFS, the length of the submarine was used as a baseline to triangulate a bearing to a target by the time of arrival of the sonar signals at the 3 PUFFS sonar receiver units. The GUPPY III submarines filled the gap for patrols until the SSN program accelerated with the Permit and Sturgeon classes. In the early-mid 1970's, all of the diesel GUPPY III class were retired, some 30 years after they were initially built as WWII fleet submarines. This resin kit was from the now defunct Yankee ModelWorks. It depicts USS Clamagore in its GUPPY III configuration. Clamagore was the last remaining GUPPY III and was a museum boat in South Carolina. However the museum could not maintain upkeep and it was scrapped in 2022. I was fortunate in visiting in 2018 and took plenty of photos with my Nikon DSLR for reference.
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