The grounding of Rena is the most significant shipping accident on the New Zealand coast since Mikhail Lermontov in 1986.

Tauranga residents and business owners quite rightly question how such a thing could happen. Astrolabe Reef is marked on navigational charts and the ship was operated by qualified and experienced mariners. Every year thousands of skippers with far less knowledge of navigation pass them by without mishap.

Internationally several such groundings happen each year and measures are in place to reduce their likelihood. Adequate passage planning for ships is now mandatory and electronic systems make navigation more certain. What has not changed is reliance on people to control and operate ships.

Some decades ago it was estimated that human error was responsible for 80% of marine accidents. It might be closer to 99% if we acknowledge all the other humans involved besides those on board. People are responsible at every stage in the design, building, management, chartering, operation and support of ships.

Our temperate island paradise relies on cheap ocean transport to support a high standard of living for its four million people. That cheapness comes at a price, often paid by those least able to afford it. Container ships routinely call at four or more ports in seven days. At each port there is pressure.

Arrival: 3 a.m. Start loading and discharging containers. Stevedores vie to turn ships around faster than competitors. Visitors board: agents, officials, planners, providores, surveyors, auditors. Everyone has to see the master, regardless of the fact that he's been up all night. Often there are problems: temperamental machinery, awkward people. Set sail at 1 pm. Try to catch the tide at the next port. The ship must not be delayed - otherwise someone else will do the job faster - cheaper.

The pressure under which the master and officers work is intense. They are not machines. They are people like you and me. Yet we wonder why things go wrong.

The official casualty reports could recommend changes. Their scope is generally constrained by legislation to focus on those directly involved, often adding to, rather than relieving the pressure. Public reaction to the Rena grounding shows it is time for changes that will get to the heart of the problem and decrease these pressures. These could involve higher costs and reduce our international competitiveness. Such a move might not be popular but present opinion seems to favour protecting the things we value.