I think things would be much safer if tournament sites would just follow USAWS's recommendations. Our site gets accused of having the buoys too small and too low. Well... I follow the rule book and their recommendation. We also fill them with about 1/4 water. Considering switching to Wally buoys next year.
Every site I go to, they buoys are much bigger and much higher. Ours are not too small; everyone else's are too big! The rule book quote is below. Notice what they recommend. Make a template that matches their recommendation. If the nipple is 1-2" out of the water, pull them down! The height (3.9") is half of the width (7.8"). So the water line should split the nipple if the buoys are 7.8".
Skier and Gate buoys shall be generally spherical in shape and 20 - 28 cm
(7.8” to 11") in diameter (20 cm (7.8”) recommended), and fastened so that
they have 10 - 17 cm (3.9” to 6.75") of height out of the water (10 cm (3.9”)
recommended). They shall be of lightweight, pliable material with a smooth,
exposed surface.