In March 1944, Tirpitz was emerging from a long period of repair. The Naval Staff diary records equipment replacements, accelerated work on diesel machinery and a programme of trials. These were practical steps towards restoring a ship, rather than a single declaration that all work was complete. YT-T18
A report on 17 March, following trials on 15–16 March, described armament and machinery as materially ready with an important exception: intolerable vibration in the cruising turbine. Remaining work was to continue. That exception belongs in the account alongside the progress.
Three different questions
Could the ship move? Could its weapons and machinery function reliably? Could the crew employ the whole ship effectively in an operation? The answers need not have changed together.
On 26 March, the translated diary discussed anticipated readiness with two propellers and a later stage involving three, alongside qualifications concerning auxiliary machinery and electrical generation. Its wording about the dates is awkward. It supports a staged recovery programme, but should not be converted into a precise completion certificate without checking the German original. YT-T18
On 31 March, the programme called for maximum-speed trials on 1 April and training from 2 April until the end of May. The long repair period and personnel changes, stated as 20 percent, helped explain why training remained necessary. Returning equipment to service did not instantly restore the experience of a settled crew working together.
The trial that did not happen on schedule
The ship’s account of the ensuing air attack says that the repeat maximum-speed trial and magnetic-protection measurement planned for 1 April were postponed by 48 hours because of the weather forecast. On 3 April, preparations to leave were under way when the warning of aircraft arrived. YT-T05
The planned 1 April trial therefore cannot be cited as a successful test completed before the attack. Equally, a ship preparing to leave for trials should not be described as wholly incapable of movement.
This is the condition in which Operation Tungsten found Tirpitz: recovering capability, with unfinished work and further crew preparation ahead. The attack would force another reassessment.