That is 15 now.
He is undefeated on 127 and will resume this morning with his side on 321 for six.
How the 37-year-old has avoided being picked up by the Black Caps with a record like he has is quite staggering really.
He went into yesterday’s Plunket Shield match against Otago at the University Oval with an average just north of 42.
He has bumped up that average with some very good outings against Otago throughout the years.
The right-hander has now scored five first-class centuries against the Volts, including a high score of 226.
Yesterday’s effort was up there in terms of quality.
He stroked 15 fours and a six but had to knuckle down as well.
He lost fellow opener Bayley Wiggins in the second over and Brad Schmulian nicked out for one.
When Dane Cleaver guided an inside edge on to his leg stump, Central was teetering at 66 for three.
But Tom Bruce joined Hay in the middle and took the attack back to Otago.
He played with controlled aggression and rattled off 50 from 53 balls.
Volts captain Hamish Rutherford came up with a plan to get rid of the dangerous player.
He located Dale Phillips at a short mid-on position and Jacob Duffy enticed Bruce into a drive.
Phillips made a nice grab low to his right to dismiss Bruce for 74.
It was good reward for Duffy who bowled tightly early on.
But with Hay cemented at the other end the Stags were able to build nicely.
He clipped an Angus McKenzie delivery off his pad to the boundary to bring up his ton.
It was a beautifully executed shot and there were plenty of those to pick from.
Ben Wheeler is at the wicket with him on 29 not out.
Duffy finished the day with three for 81 but the visiting side is in solid position.
At the Basin Reserve, Canterbury is 246 for six at stumps on day one. Henry Nicholls made 97 and Cameron Fletcher is 87 not out.
Former Otago quick Nathan Smith claimed three for 31 for Wellington.
