He led by example at Harry Barker Reserve yesterday, opening the batting and scoring 108 not out.
The left-handed batsman hit several boundaries through the covers and scored heavily behind square on the leg-side.
Shaw and opening partner Baxter Mackay (59), who scored prolifically through the covers himself, put on a stand of 126 runs for the first wicket.
No.4 Rowan Smith added an unbeaten 62, smashing a six at the end.
If Landmark Homes OBR were going to make headway in the match, they needed early wickets and, though Cody Andrews bent his back, the bowlers couldn't get much out of a docile deck.
OBR tried 10 bowlers — even wicketkeeper Josh Adams shed the pads and had a go — and all but Andrews (0-27 off 10 overs) and Amit Vyas (1-25 off five) leaked runs at the rate of at least six an over.
Shaw said he was happy with the start and HSOB pushed on to get maximum batting points from their innings.
OBR bagged just one bowling point from the day for taking two wickets and both sides collected two extra competition points for the match abandonment.
OBR captain Matt Cook said Shaw and Mackay did well to deny his team early wickets.
“It was hard work out there but we toiled away,” he said.
OBR were missing key personnel and players from their second 11 and Gisborne Boys' High School filled the void.
A deluge of rain came down at 4.20pm and the game was called off soon afterwards.
High School Old Boys 279-2 off 45 overs (Carl Shaw 108 not out, Rowan Smith 62 not out, Baxter Mackay 59) versus OBR 5-1 off 1 over. Match abandoned due to rain.