Just throwing my two cents in...I think the tape measure would be the best way to go. It worked really well for the Brownie Troop Sh*t Fish Derby last year. The margin of error is slim and if it came down to it, you could figure the length out pretty acurately based on a picture. I'm sure by now, most everyone has some sort of digital picture taking device whether its on their cell phone or point and shoot camera. It's about time New Jersey shows it's tried and true with a Garbage Fish Tournament! Thanks Brian.