Complex sentence: Normally water hits the head and shoulders and immediately breaks, creating turbulence, however with the additon of the tripwire the water is forced to keep its flow consist along the entire surface of the swimmer.
Split into simpler sentences: Normally water hits the head and shoulders and immediately breaks, creating turbulence. However, with the addition of the tripwire, the water is forced to keep its flow consistent along the entire surface of the swimmer.