|Representing New Zealand|
|British Empire Games|
|1954 Vancouver||Coxed Four|
Culpan grew up in the Auckland suburb of Westmere. At the 1950 British Empire Games he won the silver medal as part of the men's eight alongside crew members Donald Adam, Kerry Ashby, Murray Ashby, Thomas Engel, Grahame Jarratt, Don Rowlands, Edwin Smith and Bill Tinnock. At the next British Empire and Commonwealth Games in Vancouver, he won another silver medal in the men's coxed four.
Culpan worked at a pharmacy in Remuera from 1948. He took ownership of the company after its former owner's early death, and changed its name to Remuera Pharmacy, which caused a stir amongst his peers as all pharmacies were known under the name of its owner, and there were several pharmacies in the suburb. He retired from the business in 2005.