Steward, with 11 boundaries and a six, carried on after key batsman Mark Fraser holed out trying to hit spinner Jessica Watkin over the fence, with Trent Hemi taking the catch on the boundary.
Hemi would finish with 2-39 from his 10 overs, while Nick Harding was conservative, conceding just 35 from his maximum overs.
However, the light covers went out immediately in the innings break as the spitting rain set in and ended play for the day.
Across the field on Tasman Tanning No2, Property Brokers United didn't mind playing water polo style for a few overs to pick off the remaining runs for a five-wicket win over Matt Burke Engineering Marton Saracens.
Six United bowlers picked up wickets as Marton collapsed to 124 all out.
Only Dan Ford (20) made another middle-order fight, supported by Bryant Galpin (20), while Jono Hicks (25) had a small flourish at the end.
United opener Tom Lance (67 not out) then carried his bat through, with support coming from Robbie Power (29).
Although their team floundered a little to be 64-5 in the 15th over, captain Gerrard Hobbs (15 not out) steadied the ship to give Lance the opportunity to polish things off in the wet.