1984 – SV Takuyo – The Hydrographic Department, Maritime Safety Agency, Japan (JHOD) deployed the newly commissioned 2,600-ton survey vessel Takuyo (HL 02) to the Challenger Deep 17–19 February 1984.[8] Takuyo was the first Japanese ship to be equipped with the new narrowbeam SeaBeam multi-beam sonar echosounder, and was the first survey ship with multi-beam capability to survey the Challenger Deep. The system was so new that JHOD had to develop their own software for drawing bathymetric charts based on the SeaBeam digital data.[9] In just three days, they tracked 500 miles of sounding lines, and covered about 140 km² of the Challenger Deep with multibeam ensonification. Under chief scientist Hideo Nishida, they used CTD temperature and salinity data from the top 4,500 metres (14,764 ft) of the water column to correct depth measurements, and later conferred with Scripps Institution of Oceanography (including Fisher), and other GEBCO experts to confirm their depth correction methodology.