For a discussion in Liners' List, I have been looking for the exact dates of the Yokohama Charters. This is what I have found here assembled in this Forum :
And also :
Apart from the starting date (27 or 30 March 1989), these two quotes seem to be in agreement (72 days in Yokohama).
The second Japanese charter was not Yokohama, but Osaka (December 1989 for 6 months), as mentioned by Ron Warwick.
Information provided by Michael Gallagher, Cunard ex historian that I posted in the topic
QE2 1980's Dates of World and extended cruises mentions the Japanese charters. When Michael is next on the forum he may be able confirm whether the ship sailed to Yokohama or Osaka in December 1989 :
Extract from 1980's World Cruise topic:
13 January –27 March 1989: ‘Round South America and Circle Pacific’ extended Cruises 74 days, 27 ports
South America: 37 days, 15 ports
(13 Jan – 19 Feb)
Pacific: 37 days 12 ports
(19 Feb – 27 March)
Note: A shorter than usual World Cruise in order to position QE2 in Yokohama for a 72-day charter (30 March – 9 June). Upon completion of charter, QE2 sailed from Honolulu to Southampton: 25 days (9 June – 3 July).In March
QE2 experienced a sudden and severe South Pacific storm while on the Tahiti – Auckland leg of the voyage. 40-foot waves and 60-knot winds. 30 passengers had to be treated for injuries by the doctor and damage included a broken piano. The weather forecast had not predicted the storm so Captain Bennell could not avoid it.
26 November to 21 December 1989: QE2 undertook another extended cruise in 1989 to position her in Japan for the 180-day (28 December 1989 – 19 June 1990) Japanese charter. 27 days, 12 ports
Note: QE2 sailed from Honolulu to Yokohama without passengers (21 – 28 December 1989).