Well, I'd scrap what you have and start over. The logbook format that
you have is suitable for operators and managers to write, for example,
the status of the plant and equipment at hourly intervals, but it does
not suit what you're trying to do.

Instead I'd make up a sheet with 6 columns, as:
A. Date
B. Start Time
C. Stop Time
D. This Run
E. Daily Running Time
F. Total Run Time by Day

Columns A through C should be obvious. I'd format the first column for
"date" however you want that to appear. Columns B & C I'd format for
however you want to enter your "o'clock" times, and D-E-F I'd format
for "h:mm" to show hours and minutes of operation.

Formula in column D:D is (at D2, and copied down however many rows):
=IF( AND( ISNUMBER( C2), ISNUMBER( B2)), C2 - B2, IF( ISNUMBER( B2),
NOW() - B2, ""))

Formula in column E:E is (also at E2, and copied downward):
=IF( ISNUMBER( D2), IF( A2 = A1, D2 + E1, D2), "")

Formula in column F:F is (same method):
=IF( A2 = A3, "", E2)

You can hide column E:E. You need to have it compute, but you don't
need to display it.

This does not have error-trapping (start times after stop times, dates
in incorrect sequence, etc.), so it's not a real "application", but you
can develop that stuff. Your sheet arrangement above is entirely
unsuitable, but an arrangement like this will let you show plant
operations for months and months ... on a single worksheet.

And your actual hours of operation in your example are 9:30, not 9:00.

Chris