this system is intended for use during a regatta to indicate the distance between a sailboat and a race course marker buoy being rounded as part of the race . the system involves a transmitter on the buoy and a receiver on the boat . the buoy transmitter sends both a radio signal and an acoustic signal . the boat receiver detects both the radio signal and acoustic signal . the boat receiver measures the time delay between the radio and acoustic signals . this time duration is converted to a distance and the boat receiver displays the distance information .