Apparently...

"A bunch of the first boats went to the original mark and did not realize the course had been changed until they saw a RC boat picking up the original mark."

Might be those new-fangled invisble Charlie flags...

EDIT: Whoops, we posted at the same time. Minature marks certainly make it tougher. The bigger issue is normally having all the marks the same color and shape, and trying to rectify it with a black band or something. That's OK on a lake, much different in rough, open water. BUT, the complaints are generally the same.

Mike