Havant had to spread the field far and wide as the 18-year old spin all-rounder lashed 139 in an innings changing 138-run partnership with Oscar Marshall (40) as Sway, from 141-4, totaled 281-5.
A three-wicket spell by Jon Waller (3-27) reduced Havant to 125-7 before Ben Turk hit back with a seven-sixes 129 for Havant, who closed with a respectable 249 all out.