It's a little counter-intuitive, but the answer is 21.
I looked at it from a real clock and wound it around manually.
Here's what I think is happening.
It crosses the hour hand roughly at the following times:
crossing crossing time
1 1:06
2 2:11
3 3:17
4 4:22
5 5:27
6 6:33
7 7:38
8 8:43
9 9:49
10 10:54
11 12:00
12 1:06
13 2:11
14 3:17
15 4:22
16 5:27
17 6:33
18 7:38
19 8:43
20 9:49
21 10:54
That's 21 crossings.