Doing a 13u game (80' bases) alone, there was a sinking liner hit to straight-away center. The cf came charging in & made a great diving/scooping catch. Offensive coach disagreed with my call but is a former umpire and understood my being over 100' feet away wasn't going to bring the results he needed.

What's the best position for me to get to to make this call? Sprint towards 2nd or work down 3rd baseline to get an angle??

Well, I don't know about "official" mechanics, but I come down the third base line on such a call. My reason for this is twofold. First, I get a better angle, in my opinion. Second, I typically can see the runners better in their tags, if there are runners on base. And if I have a runner on third, I'm running down the third base line in foul territory so that I can see him as well.

Bottom line, you position yourself the best you can, so that you can see as much as you can. Yeah, you may miss a call on a catch in deep center because of the distance. Do the best you can do, and move on. Especially when you're working the big diamond alone!

Bob

Sinking liner to CF don't allow much time to sprint toward 2B. But going toward 3B line is not optimum either. I would move toward the right or left edge of the mound, depending on the direction of the ball, but not in a sprint, for a sinking liner. Better to be set for the catch than on the move.

100 feet in CF sounds easy. Try a fair/foul call into the sun down a line on a home run/foul ball.

Wrong way!
 

One man mechanics, sinking liner directly at the CF...
you go up the first baseline to the 45 foot mark, that's about as far as you can get (you can cheat a foot or two inside the line, but don't compromise the angle).

Several things are in play here: the angle is better than straight on. If the kid doesn't catch it, where will he be? Likely, either on first or going to second. With 80' bases, you are in a perfect position run downs, advance to 2 or a throw back to first. If you go down third and the play is at second or the throw back to first, your going to be guessing.

Hustle, get a good look and sell it.