This drill looks like sighting, but I do not use this drill to teach sighting. I do use it so triathletes get an idea of how hard it is to get the head fully out of the water high enough to take a breath through the mouth while looking straight ahead (it’s hard). The main use of this drill is to force an athlete to pull extra hard in order to generate enough force to keep the head up. The force vector coming off the arms points in the wrong direction – more down to keep the head up than backwards to move the body forward, but the magnitude of the vector is large. When an athlete then puts their head in the water after doing this drill and pulls just as hard with the proper force vector, they should swim quite fast. I sometimes use Tarzan drill as a precursor to sprinting.