Horatio Hackenbacker's submarine

A model submarine was owned by Brains. It had a sonic beam.

History
In an account dated to January 1965, Brains was performing an experiment using it in the Tracy Island swimming pool. During this experiment, Jeff warned him that Alan would soon be out for his swim, which Brains claimed would upset the sonic beam. Indeed, Alan arrived shortly after, throwing a towel from around his neck to the ground, and jumped in, causing a splash. Alan then apologised for ruining Brains' experiment. (TV: The Man from MI.5)

Other sources dated the activities of International Rescue to the 1990s, (PROSE: The Dying Days) the 2060s, (PROSE: Titan Declares War! et al.) and the 2080s. (PROSE: Captain Scarlet in Death Crash! et al.)