Australia's six Collins submarines are scheduled to retire from 2030, and planning for their replacements needs to start now. A new Defence policy document - also known as a white paper - due next year will say exactly how many new submarines we need and what type they should be. The government wants to establish a regionally dominant conventional submarine capability. That means having better subs than our neighbours and others in the region - not a big call considering Indonesia operates two 30-year-old German subs. However, Indonesia is buying new subs, as are other regional nations.

For a nation dependent on sea trade with vast ocean surrounds, submarines are appealing. They can sink other ships and submarines, fire Cruise missiles at land targets, insert special forces, plant seamines, conduct covert surveillance and gather intelligence. While ships and aircraft can also do much of that, subs do it invisibly for weeks at a time. For an adversary, they are a significant deterrent - no sea commander lightly ventures where enemy submarines lurk. Submariners tactlessly refer to surface vessels as targets.

Too right. Defence Minister David Johnston says he just doesn't know what the next lot will cost and neither does anyone else. The Australian Strategic Policy Institute reckons perhaps $36 billion - triple that amount for the cost of maintaining them over their operating life. It will certainly be Australia's most complex and costly military acquisition. In tough financial times, the government must justify this sort of money on subs instead of hospitals, education, social services and infrastructure.

The previous two white papers (2009 and 2013) nominated the number, although why has never really been explained. It likely stems from a calculation of potential threats and the numbers needed for patrols in the Pacific and Indian Oceans. All 12 rarely would be available at the one time because crews need rest and submarines have to be resupplied and serviced. The new white paper could conclude we need fewer than 12, or more. Sure - with sufficient resources. But in 2009, the navy didn't have nearly enough crews for all six Collins subs and was hard-pressed to get more than two at sea at once. So lots of eyebrows were raised at the prospect of 12.

Plenty of nations make subs which could be purchased for far less than we'd pay to have them built in Australia. Problem is we have particular requirements: European models are too small and lack the range and endurance to operate in the Indian Ocean. New Japanese Soryu class subs, about the same size as Collins, are a possibility but there's no certainty Japan would agree to sell them to us.

Two options remain: an evolution of Collins (expensive) or a brand-new Aussie design (very expensive). The thinking is that Collins can now do most of what's needed, so the design could be made bit longer with the installation of newer systems. This becomes a new design when the hull diameter is increased. Either could still be a lot like a Collins, a derivative of the Swedish Kockums Type 471. This would involve difficult intellectual property issues. Whatever is decided, it will be assembled in South Australia, as were the Collins boats.

Considering we'd never built a submarine and not that many warships, it was quite an amazing achievement. But there were moments along the way. The subs were noisy and unreliable. That's mostly fixed and Australia has gained considerable submarine expertise. Having made just about every possible mistake, Defence is confident we can do much better next time. For range and endurance, there's nothing better. But successive Australian governments have ruled out the nuclear option for a range of reasons. Australia lacks the nuclear infrastructure, so we'd be wholly beholden on the vendor, either US or UK, for support. Likely they would retain a veto on how we use them - if they agree to sell or lease them in the first place.

Better than on Das Boot. Subs are still cramped and crews go for long periods without seeing the sun or anything else outside their world. Unlike the older Oberon subs, those on Collins boats don't need to hot bunk. The food is good - if it wasn't there'd be problems. Women serve on Australian subs. Submariners are an elite group who proudly wear the coveted "dolphins" qualification. Prospective submarine commanders must pass the "perisher", the world's most ruthless promotion course. Those failing to make the grade will never serve on a submarine again.

Source : AAP