Command, and is primarily focused on supporting the activities of the Sixth Fleet. The SDV suffered from reliability concerns early in its lifespan. LCDR Doug Lowe, a member of SDV Team 1 in the 1980s, reported that his team's SDVs were operational less than 50 percent of the time. However, reliability improved with usage: LCDR Lowe later commanded SDV Team 2 in the 1990s and reported that his subs were ready more than 90 percent of the time. The main failure of the SDV is its poor mobility. The SDV can only be effectively deployed from specially modified submarines and surface ships. Although it can be transported by C-130 airplanes, the relative scarcity of vessels capable of deploying an SDV limits its usage. Submarines are the preferred means of deployment, as enemies can see a surface ship deploying an SDV with a crane, further limiting the SDV's mobility and usage. Modifying a surface ship to launch and recover the SDV through an underwater door, like the Italian Navy had done for its human torpedoes in WWII, would have helped alleviate this problem. The Special Boat Service of the United Kingdom Special Forces operates three Mark 8 Mod 1 vehicles. Operators United States Navy: Navy SEALs SEAL Delivery Vehicle Team 1 (SDVT-1) SEAL Delivery Vehicle Team 2 (SDVT-2) Royal Navy: Special Boat Service Gallery See also Chariot manned torpedo Human torpedo References External links Video of a SEAL Delivery Vehicle in use Military.com article USS Nautilus Museum exhibit Submarines of the United States Navy United States Navy SEALs Wet subs Midget submarines