September 4, 2006: The U.S. Navy is taking it's oldest, and only diesel-electric, submarine out of service. The USS Dolphin (AGSS-555) is a research sub that entered service in the late 1960s. It can dive to a depth of 3,000 feet. Displacing only 950 tons (about half the size of diesel electric combat subs), it has a crew of 66. The Dolphin just underwent a $50 million, three year, round of repairs and upgrades (2002-5), but the sub costs $18 million a year to maintain, and the navy can no longer justify the expense. Since the end of the Cold War, the Dolphin has been used more for civilian science projects. Again, the high cost of maintaining the Dolphin will probably prevent any civilian scientific organizations from stepping forward to pick up the tab.
Over the last thirty years, the Dolphin was used as a test bed for many new submarine technologies. However, because of its unique design (especially the internal structure), it could not operate much like a conventional diesel-electric combat sub. However, the diesel-electric power plant did leave the navy with some sailors and officers familiar with this technology, despite the rest of American subs being nuclear powered.