You know you've spent too long in type IX's when you...
Actually grow a beard whilst playing
Get annoyed that a convoy has interrupted your cup of tea / book
Start including imaginary crew in your patrol reports
Hesitate to crash dive because that aeroplane might mean you don't have to suffer the return voyage
Let a cargo ship pass you because you might see a BIG cargo ship in a few weeks
last but not least.....
Start believing that you use less fuel submerged
