Please can you help me solve this problem?

I want my sims, when they go to sea to be away for a long time, so I set Tuning - Hours per Day in the BCONs to 23. The idea is they go to sea at 8 a.m. and return at 7 a.m. the following day. However, my test sim goes to work OK but is then immediately returned, as though the game is reading +23 hours as -1 hour work day length. I know some of the Maxis careers have a working day that goes past Midnight, so I feel I must be missing something obvious.

I have attached a copy of the career in case anyone would like to look at it.

Thank you.

EDIT: On further experimentation, I seem to be OK up to 22 hours work day length, but not beyond. Is this normal?