Richard Thursby wrote:
My game didn't quite get to the time control but it wasn't explained (I think) at the start how/when the extra 30 minutes would be added. Having seen the board next to me past move 40 and still having about the same time on the clock as my own board, I inferred that it would be added when one clock expired the first two hours.
This is rather a secondary question about digital clocks as to whether to use the move counter because it requires the players to press the clock after every move (and only then). I am sure I have seen this advanced as an argument not to use digital clocks because of confusion that can arise (and hence arguments).
According to the rules:
6.2a. When using a chess clock, each player must make a minimum number of moves or all moves in an allotted period of time and/or may be allocated an additional amount of time with each move. All these must be specified in advance.
6.3. Immediately after a flag falls, the requirements of article 6.2 a. must be checked.
Say the time control is 40 moves in 2 hours. You reach the time control at 2 hours, not 40 moves (hence time
control). So, only then should the time be added, i.e. if you've made more than 40 moves. The digital clock is therefore doing exactly what it's supposed to be doing. Digital clocks do not need a move counter, either you're writing your game down, or the arbiter is writing it down for you in a time scramble. So the arbiter knows how many moves have been made.
This is a poor argument against the use of digital clocks, because it's actually following the rules! When people in congresses start picking up clocks and rewinding them after they've made the right number of moves, they shouldn't be. In practice, it makes no difference. But that's why the clock is as it is.