Captain Rennie, head of ports and terminals at the South African group, passed away on Friday in Durban.
Grindrod said he would be "deeply missed”.
He joined the group in 1978 and has held various positions and directorships since.
As a holder of a master mariner's competency degree, he dedicated his life to the freight and logistics sector.
He was also awarded a meritorious service award from the chief of the South African navy.
Rennie
