Arvel Hernandez 
220a Hw.1

Speed of sound in air: 1.128 ft/ms (from The Science of Musical Sound
				     Pierce, john)

Speed of sound in water: 1.128 ft/ms  x 5 = 5.64 ft/ms 

First Impulse: approx. 215.88 ms

Second Impulse: approx. 228.08 ms

Time interval between impulses: 12.20 ms

Distance between boats: 5.64 ft/ms  x 12.20 ms = 68.81 ft appart

According to my (and calculator.com's) calculations the boats are
approximately 68.81 feet apart.