Keep in mind that 3 centimeters equals just 1.2 inches. I suspect that could only be a few thousandths of a second. From Sports Day Top Stories: "... In this case, they could prevent some swimmers from records and Olympic and Olympic Trials dreams. And they're causing Texas A&M embarrassment.
The university hosted a Texas Senior Circuit meet at its Student Recreation Center Natatorium last Friday through Sunday, completing five of six sessions before meet organizers determined bulkheads in the pool were incorrectly placed and the course was three centimeters too short – measuring 49.97 meters instead of 50. ..." [Link]
Photo from the official website of Texas A&M athletics: [Link]