telling the time

["Sulu' wa'" <kli@doublezero.uklinux.net>]

On http://www.geocities.com/teresh_2000/kliadda.html (the addenda to Klingon grammar) it discusses 
telling the time by means of hours. Two examples it gives are
rep cha'maH		twenty hours (8 p.m.)
rep loS wejmaH		four hours thirty (4:30 a.m.)
and this is supposedly canon (from startrek.klingon). But this seems to have a problem: is {rep wa'maH wej} 
ten hours three or thirteen hours (10:03 or 13:00 respectively). In an informal situation, you might expect it to 
be the latter, but for military operations and many other situations, it is ambiguous.
Am I missing something obvious, or am I justified? Is there a way to tell which this is, or to make it clearer?
Please enlighten me.
--
'u'wIj vuSmey Del HolwIj vuSmey
 - Ludwig Wittgenstein (almost)