Grindrod Shipping chief executive Martyn Wade has no problem doing his part as a shipowner to lower carbon emissions, but charterers also need to pitch into this effort, he said.

Over the past few years, owners have spent millions of dollars on installing exhaust-gas scrubbers and buying eco-ships to meet international regulations on lowering their ships' carbon footprints.

"I always have a bit of a beef about the charterers who appear on the front page of TradeWinds proclaiming their green credentials are the same individuals that at times will take an old ship because it's 50 cents cheaper," he...