Malden Island
The next test series consisted of a single trial known as Grapple X. To save time and money, and as HMS "Warrior", "Alert" and "Narvik", were unavailable, it was decided to drop the bomb off the southern tip of Christmas Island rather than off Malden Island. This was just from the airfield where 3,000 men were based. This required another major construction effort to improve the facilities on Christmas Island, and some of those that had been constructed on Malden Island had to now be duplicated on Christmas Island. Works included 26 blast-proof shelters, a control room, and tented accommodation. To provide some means of chasing away intruders, the destroyer was allotted. HMNZS "Rotoiti" and "Pukaki" reprised their role as weather ships. A cargo ship, the SS "Somersby" was chartered to bring tentage and stores to Christmas Island. Monitoring equipment was set up on Malden Island and Fanning Island, and the observation posts on Penrhyn Island and Jarvis Island were re-established. Oulton noticed that: