John -

I had to read your post twice before I realized how "one-oh-five" could mark a dog twenty seconds over.It might help if you included the "obvious" sentence that you've left out, that "one-oh-five" could be interpreted as 105 seconds when only heard, not written out.

If the volunteers are from the club, do they also have dogs competing? If their dogs get scored incorrectly a few times, they'd probably be more careful. ;)

Maybe have a session with the volunteers with examples of how confusing it could be - you could call out times to the volunteers and have them interpret what you meant. Then tell them the "correct" answer. Sometimes seeing the problem first hand is what it takes to correct it.

Or develop a format of always using minutes and seconds, even if the score is then "O minutes, 59 seconds".

It's not feasible for practice meets, but the bigger trials have a large digital clock that the judge (and the audience) can see, eliminating any confusion.

Unless you just wanted a math answer to the question, in which case the time will always be 40 seconds over the real time if the score is between one minute (60 seconds) and two minutes (120 seconds) and 80 seconds over if the dog runs over two minutes, say, in 2:02 (122 seconds, not 202 seconds).

I'm not sure what you mean by the "most plausible" error - one the judge won't catch on his own? I would suppose that the closer to one minute the dog runs, if the judge is watching at all, he would realize that the timer meant 1:02, not 102, and that for the slower dogs, the error might not be detected.

Still clear as mud.

campfire