Torped 613 (TP613) is a heavyweight torpedo still in use by the Swedish Navy. It is wire-guided and has a passive sonar sensor that sends back information through the wire. The torpedo was developed in the 1970s as a cooperation project between Denmark, Norway and Sweden. Testing was done during the period 1981-1983. Like the older Swedish Torped 61 introduced in the mid-1960s, it is driven by alcohol and hydrogen peroxide, which gives long range and a minimum exhaust trail. The torpedo is planned to be replaced by the more modern Torped 62. Short history of the TP61-series torpedoes: