Last week I was in Hawaii for my brother’s wedding.  We stopped in to visit the battleship Missouri in Pearl Harbour. Built in 1944 and retired in 1994, she was amongst the largest battleships ever built, massive, imposing and sporting some of the largest guns ever made.

While we were standing in the bridge, the one thing that stood out was the telephone, that’s right – singular – one analogue telephone for the whole ship. It looked a little like a very old payphone without the coin slot. This entire class of ship had become obsolete by the 90’s not because of the firepower, but because of a lack of smarts.

That made me reflect on the tendency in the mining industry to keep our ageing equipment alive. At the end of a machine’s life there is a choice; you can rebuild or replace.  Sure, rebuilding is less capital, but what is the productivity opportunity cost? It often pays to simply replace the equipment and bank the productivity gains.