Answer I found by Doug Steele, Microsoft Access MVP
I tried it and it told me in Hours, minutes, Seconds
FormatDecimalTime(16.83)
16.83 hrs = 16:49:48
at http://www.pcreview.co.uk/threads/converting-decimal-time-into-hh-nn-ss-time-in-access.2793160/
So use it something like...