On 26 March 1913, Lindemann traveled with his parents to Flensburg for his medical examination at the Naval Academy at Mürwik. The strong financial background of his parents made him a suitable applicant for the Imperial Navy, as the costs associated with a naval education in 1909 were 800–1,000 Marks per year for eight years. By comparison, a metal worker earned 1,366 Marks annually and a teacher 3,294 Marks. Only 5 percent of the German population at the time earned more than 3,000 Marks annually. However, the doctor certified him as fit only for limited duties (), as pneumonia in childhood had left him unfit for service in U-boats. After a second examination, he was accepted on probation, and Lindemann became one of the 290 young men of "Crew 1913" (the incoming class of 1913). He was officially enlisted in the Imperial Navy as a (midshipman) on 1 April 1913.