The port corporation's recently released annual report shows the port made a profit of $19.5 million in 2011-12, up from $17 million the previous year.

"It was a fairly good result," corporation chief executive Dom Figliomeni said.

The port's profit came in a year when regular customer BlueScope announced it was reducing steel production by half and withdrawing from the export market.

"[That] had a significant impact on activities in the port, not only in relation to revenue but the corresponding reduction in port throughput, such as a decrease in port imports, exports and vessel visits," Mr Figliomeni said.

He said the effect of the BlueScope reductions had been felt for only "eight or nine months" of the financial year, and he did not expect it to impact on this year's profits.

"We've got quite a big mix of trade and BlueScope is not really a significant revenue-earner.

"The cars are our main revenue-earner so that's a big focus for us," he said.

"The cars" are the port's car terminal, which handles motor vehicle imports. Since its introduction in 2008, it has grown substantially and this year made up more than half of the value of trade through the port.

Mr Figliomeni said the terminal was an example of how the port was moving away from a reliance on coal, BlueScope and grain for revenue.

Other areas of diversification included a biodiesel production facility and the Cement Australia plant, both being built at the harbour, and the work being done on a rail master plan for the outer harbour.

"It's been a conscious plan of the port to diversify wherever possible," Mr Figliomeni said.

"Part of that is the cars, and we continue to diversify with the biodiesel and the Cement Australia project. They're all part of that longer-term diversification. Rail operations is part of that diversification.

"It's important to make sure you diversify your revenue base to make sure you don't rely totally on one commodity."