OVERVIEW: The T1 Mod 1 is a heavyweight, wire-guided, steam-propelled torpedo developed as a postwar upgrade of the German G7a (TI) torpedo. It was intended to improve mid-course guidance by incorporating manual wire control without modifying the original propulsion system.

DETAILS: "T1" is the postwar designation applied to the German G7a torpedo, and "Mod 1" refers to the addition of wire-guidance capability. The G7a was originally introduced in 1934 as a steam-driven torpedo using a wet-heater propulsion system and gyroscopic steering. During the Cold War, Norway and Denmark retrofitted remaining G7a stocks with a manual wire-guidance system that allowed steering corrections after launch, typically by mounting a wire spool and adding control electronics. The propulsion, speed (up to 44 knots), and warhead remained unchanged from the original G7a. This upgrade extended operational relevance into the 1990s for coastal defense and training.

TYPE: Heavyweight Steam-Propelled Wire-Guided Torpedo

FUNCTION: The T1 Mod 1 is launched from 533 mm torpedo tubes on submarines or coastal platforms. It uses steam propulsion and gyroscopic stabilization for basic trajectory, with manual wire-guidance allowing mid-course correction before transitioning to unguided terminal run.

NOTE:
IOC: 1934 (G7a), late 1960s (T1 Mod 1)
Manufacturer: Germany (original G7a by Kriegsmarine; wire-guided upgrade by Norway and Denmark)
Operators: Norway, Denmark
Platforms: Norwegian coastal torpedo batteries, Kobben submarines, and fast attack craft

SOURCE:
Wikipedia G7a torpedo: https://en.wikipedia.org/wiki/G7a_torpedo ; Sightraider Herdla Battery: https://www.sightraider.com/herdla-torpedo-battery-defending-bergen-in-wwii-and-the-cold-war/ ; Forsvarsmuseet Norway Coastal Defense history: https://forsvaretsmuseer.no/armehistorie/herdla-batteri