He said it was a consequence of the pipfruit harvest starting two weeks earlier than normal and fruit being shipped straight to Asia instead of storage.
"I suppose it is a good thing, but it has a rough edge to it."
JM Bostock produce company owner John Bostock said it was simply "not good enough" shipments were being delayed, making trading "very difficult".
"It's an ongoing issue we hope to resolve with the port, council and the owners ... this situation is letting the customers down."
When asked what the cost of delayed or diverted shipments on his company had been Mr Bostock responded: "You can't put a price on the damage it is having on reputations."
"We have been talking about this issue for three years now and from my view it just seems to be getting worse and worse."
Napier Port chief operating officer Chris Bain said March was "considerably stronger" than expected.
"Based on throughput to date we expect the March total will be 20 per cent to 25 per cent bigger than March 2013. We budgeted for a little in excess of 10 per cent growth," he said.
"Growth of up to 25 per cent has tested capacity in a number of ways and a host of short-term solutions have had to be deployed over recent weeks. Every available piece of equipment and staff member is committed and working considerably extended hours.
The port's container terminal was "the single pinch point" for both export and import regional supply chains.
He said seasonal exports appeared to have unexpectedly moved "strongly into containers this year".
A new delivery standard for Japan exporters had exacerbated the problem.
"Instead of containers normally being delivered to port mainly on Monday/Tuesday, they now occur on the prior Friday/Saturday. These containers now sit on port an additional three days, further reducing storage capacity."
Smoothing the flow of deliveries was a "particular challenge".
"We certainly regret that truck turnaround times have degraded in the face of the large unforeseen growth spike.
He said the port turnaround time for March was so far an average of 36.3 minutes, but last week's was 45-50 minutes. The target is 30 minutes.
"Tuesday was particularly frustrating due to a series of forklift breakdowns, struggling to cope with continuous 16-hours-a-day running, 7 days a week.
"We clearly need to significantly invest to boost container terminal capability within the next 9-10 months. Replicating how we currently operate is unlikely to bring the level of service and capacity future proofing now needed.
"Some diversions have recently occurred, which is concerning. The increase in capacity investment should ensure that this minor loss of business can be convinced to return again."
Mr Beaven said he was heartened the port was upfront about the problem.
"As the owners of the port the council has to take this matter seriously because it is an essential service for the economic welfare of the region."
