The Legacy of War Monday, 08 February 2016

Startled awake by sirens in the early hours of 17 February 1944, the Imperial Japanese Navy rushed to their posts to defend the Combined Fleet Base in Chuuk Lagoon, Micronesia. Operation Hailstone, a two-day aerial and surface attack by the US Navy, devastated the base. Over 47 ships and 4,000 lives were lost. Today, the Chuuk Lagoon wrecks are both an important historical site and a world class diving destination.

The destruction in Chuuk Lagoon was, but one small incident in World War II. Thousands of ships were sunk, each carrying their own bunker and many carrying shipments of oil and aviation fuel to support the war effort. The New Scientist estimated in 2010 that anywhere between 2.5 and 20 million tonnes of oil is still contained in sunken shipwrecks. As a comparison, the Deepwater Horizon incident released about 1.1 million tonnes.

Any wreck left on the seabed will corrode and eventually collapse. Sporadic incidents of wrecks collapsing and releasing oil into the environment have occurred.  Corrosion is a time-based event. If corrosion is not controlled, future spills are inevitable. Given the vintage of these wrecks and the corrosion rate of steel in seawater, the world could soon be facing a series of pollution incidents. The effects in environmentally sensitive areas, or areas of concentrated WWII naval warfare such as the Baltic Sea or South Pacific islands like Chuuk, could be devastating.

The deterioration is not inevitable. Dr. Ian Macleod of the Western Australian Museum has pioneered in-situ conservation of shipwrecks using cathodic protection techniques commonly used on subsea oil and gas facilities. Attaching sacrificial anodes slows down the corrosion process, and replenishing anodes as they are consumed means that this deterioration can be suspended almost indefinitely. The oil and aviation fuel can stay safely contained. Historic wrecks and artefacts can be preserved for future generations.

Dr. Macleod has dedicated a major part of his career to study and conserve shipwrecks. He participated in expeditions to Chuuk Lagoon in 2002 and 2007 and has built a predictive model for shipwreck corrosion. Perth-based engineers Allison and Chris Selman volunteered to re-survey the Chuuk Lagoon wrecks in 2015. Their underwater video footage is being considered for inclusion in a National Geographic documentary. The results from the historic survey will be used to design cathodic protection systems to stabilise the most at-risk wrecks. Once proven to be successful, the technique is applicable to wrecks worldwide.

Dr. MacLeod plans to establish an international foundation for shipwreck research and conservation. The first project for the foundation will be to conserve the Chuuk Lagoon shipwrecks.  Expressions of interest are being sought for corporate sponsorship and support.

For more information:

  •  Shipwreck corrosion, shipwreck foundation and conservation  |  Dr. Ian MacLeod 
  •  Chuuk lagoon survey, survey documentary, video footage  |  Allison Selman 

Title image caption: Engine room in the Kensho Maru. Copyright Liz Rogers.
Body image caption: Chris Selman holding oil sample from Shinkoku Maru. Copyright Allison Selman.