During the late 1990s, a combination of low recruitment and retention rates across the RAN resulted in the number of trained submariners falling below 40% of that required. As an attempt to retain submariners, the RAN offered a one-off A$35,000 bonus in 1999. Other measures introduced around the same time included priority transfer of volunteers for submarine training and rotating submariners between sea and shore assignments to relieve them from continual sea service and prevent burnout. A year later, these measures had increased submariner numbers to 55% of requirements.