A rising tide lifts all boats. Specifically, 3 hours after low tide, all the boats in the harbor are 7 feet higher than their low-tide positions. And 4 hours after low tide, the boats sit 9\frac{1}{3} feet above their low-tide positions. Since high tide comes (about) 6 hours after low-tide, what will the day's "tidal range" be, the overall difference in height between high tide and low tide?