HMAS Ovens - conservation and restorationIan MacLeod's blog | Created 1 decade agoAhoy there! Many of you who have visited the WA Museum – Maritime down at Victoria Quay in Fremantle would have noticed HMAS Ovens sitting proudly on the slipway next to the museum. HMAS Ovens is a former Royal Australian Navy Oberon Class submarine. Ovens was laid down by Scotts Shipbuilding and Engineering Company at Greenock, Scotland on 17 June 1966, launched on 4 December 1967 by the Viscountess Slim, and commissioned into the Royal Australian Navy on 18 April 1969. Ovens became the first Royal Australian Navy submarine to fire an armed Mark 48 torpedo, when she sank the decommissioned Bathurst-class corvette HMAS Colac on 4 March 1987. On her return to port, Ovens flew a 'Jolly Roger' to indicate a successful mission: the first time a Royal Australian Navy submarine had done so. As conservators, our job is to ensure that the Museum collections are kept in good condition so that future generations can benefit from the information that they tell us about ourselves and our environment. The challenge for conservator Dick Garcia and myself with the Ovens is to make sure that she remains ship-shape, inside and out! As you can imagine, this is a very large job and takes a lot of time! We look upon it as our version of the Sydney Harbour Bridge – once we finish working our way through all of the thousands of jobs at the site, it is time to start again! At the moment, work is being undertaken on the slipway in collaboration with Challenger TAFE students who are assisting in the removal of iron corrosion (rust) and debris from the slipway site and eventually will help to apply protective coatings to the cleaned surfaces. Conservator Dick Garcia with one of the Challenger TAFE students. Photo by Isa Loo. Image copyright of WA Museum. Metal corrosion is initiated in the presence of oxygen and moisture and is accelerated in a marine environment (the chloride ions in seawater). The iron ions interact with the oxygen and water to produce iron hydroxide which then in turn further reacts with oxygen and water to form a hydrated iron oxide, commonly known as orange-brown rust. Eventually, this process will eat away at the iron and make the overall structure weaker, which is why we are removing all the loose corrosion so that moisture is not further trapped behind these layers causing further deterioration. Photo of corrosion on bogeys. Photo by Isa Loo. Image copyright of WA Museum. The first step is to water blast all the corrosion and debris from the bogeys. The next step is to use pneumatic hammers, chisels and needle guns to remove the remaining loose material so that the metal is back to a uniform surface. Water blasting corrision. Photo by Isa Loo. Image copyright of WA Museum. Equipment used to remove loose corrosion. Photo by Isa Loo. Image coyright of WA Museum. Bogeys after treatment. Photo by Isa Loo. Image copyright of WA Museum. Once the loose corrosion and debris has been removed, a coating will be applied to as much of the clean metal as possible, which will act as a barrier against oxygen and moisture so that the iron will remain in better condition for longer. Some components will even be painted to their original colour schemes! More on that next time!