By the German's reckoning, there would be 33 golds in the room -- more than many countries have won in over a century of competing.
Chief coach of Britain's men's team, Grobler is a phenomenon -- even if many people outside of his sport would not recognise him if he knocked on their door wearing a name badge.
Arguably the most successful coach in British sport, if not the world, the former East German has mentored champions at every Olympics since Munich in 1972, excluding the boycotted 1984 Los Angeles Games.
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With Britain, he has personally coached gold medal-winning crews at every Games since 1992 -- the first two with five-times gold medallist Steve Redgrave and four-times champion Matthew Pinsent.
As he works towards a likely farewell in Tokyo in 2020 -- "I think I should be honest. I shouldn't discuss it now, but yes," he told Reuters when asked if it would be his last -- the 71-year-old is finding new ways to get the best out of his rowers.
"It would be totally wrong just to copy (past programmes)," he explained in an interview during a UK Sport event to launch an 'Athletes Futures' fair at the Bisham Abbey high performance centre.
"Of course, some things are the same, you will not change everything, but as a coach you have to adapt always to the new situation, to different athletes, to their habits and problems they have.
"You have to think about your programme so it's not just... doing the same thing every time again because the sport moves on," said Grobler, choosing his words carefully in heavily accented English.
"What was good yesterday will not be good for tomorrow," added the man who arrived in Britain in 1991 and was based with the Leander club in Henley-on-Thames, this year celebrating the 200th anniversary of its founding in 1818.
NEVER LOOK BACK
Grobler has a reputation as someone who does not look back, perhaps inevitable for someone who started out in the old East German system with its murky past, preferring to focus on the next challenge without sentimentality.
A famously hard taskmaster, he has had to be ruthless in deciding who gets the golden ticket and who misses out after years of sweat and toil. But there are signs of a slight softening.
"I'm getting older now," he smiled. "At the moment, as long as I'm in the business, I will say I have to look forward. I might when I finish, sit down and think 'hmm, it was a great time'.
"I was thinking now of inviting all my successful athletes, and that's quite a lot of Olympic gold medallists, and having a dinner. That's maybe a little bit of sentimental thinking before I have even finished, to do that.
"I have never been sitting down so much with them after the Olympics, because the show goes on and the next generation is already waiting," he added.
Rowing has been a regular contributor to the medal table, with Britain second overall in Rio de Janeiro in 2016, but as in other sports athlete welfare, career planning and personal development is increasingly a big part of the job.
That is something Grobler, who says he treats all his athletes as "gold dust" and with respect even if they do not ultimately make it, is particularly pleased about.
"If an athlete comes to us and takes all the pain, he has a dream to win a gold medal. I think we would lie if you said that's not important," he said.
"But what is important now, and that's where I think we are really moving on and doing a good job, is bringing that other aspect in as well... to help the athletes, not just using them for medal winning.
"We are seeing the athlete as a person."
(Reporting by Alan Baldwin; Editing by John O'Brien)
