About 13 hours and 9,000 kilometres away from Japan the Sendai tsunami still had power to push huge amounts of water in and out of Tauranga harbour when the shock waves began arriving on Saturday morning.

The Port of Tauranga tide gauges tell the story.

'It kept going the same way, though it came to a stop at one stage,” says Port of Tauranga operations manager Nigel Drake.

The incoming tide stopped, then accelerated to about four knots of flood in about 20 minutes.

'From just before ten past ten up till about 10.22am there was a massive difference there,” says Nigel.

'If it stopped and got up to four knots over a very short period, that's a massive amount of water. And this is after it's travelled how many thousands of miles.”

Some of the estimates of current speeds from 12 knots to 20knots from further north may have been over estimated says Nigel.

'If you see the tide rushing out our entrance past the buoy you could make a judgement on that and we never get much past four knots, it is very easy to overestimate,” says Nigel.

'That amount of water going past a stationary object is quite impressive.”

The port cancelled ship departures on Saturday morning.

'One actually came ahead a bit earlier and we got it out at five that morning,” says Nigel. 'The other one was shifted from Sulphur Point to this side for bunkers, and then it was going to sail. We stopped the bunkering operation at 6am as a precaution, and it didn't start bunkering again until 10am and then sailed at 2pm.”