Yesterday's release of the Coles review report into the availability of Collins Class submarines was very illuminating. As well as telling us that the Collins has some life in it yet, it shed a bit more light on past performance than had been previously unavailable in public.

In particular, after the 2008/09 reporting year, Defence stopped reporting availability data for the Collins fleet, instead rolling it into a single number for 'major combatants'—ie submarines plus frigates. But figure 3 from the latest Coles report (PDF) and data from past Defence Annual Reports allows us to produce the following chart.

This graph updates the figure that Mark Thomson and I produced for our previous work on submarines. Historical data is in blue, estimated data in red. Perhaps it's not too surprising that the 09/10 figures were deemed unfit for public viewing.

Sources: Defence Annual Reports (blue), estimates based on Coles data (red and black)

Andrew Davies is a senior analyst for defence capability at ASPI and executive editor of The Strategist.