View of the Endeavour River. Silentworld Foundation collection SF001479.

Iron ballast from HMB Endeavour

HMB Endeavour runs aground — time to throw some items overboard...

On 10 June 1770, HMB Endeavour under the command of Captain James Cook was sailing north along the east coast of Australia. At 11 pm, it struck a reef and started taking on water. Desperate to lighten the ship, the crew heaved nearly 48 tons of material over the side, including ballast and cannons. At the next high tide Endeavour was pulled free. The crew spent the next six weeks repairing the ship at what became known as Endeavour River in Queensland.


View of the Endeavour River. Silentworld Foundation collection SF001479.

An account of the incident was published in 1773 by John Hawkesworth in Volume 3, Chapter V, Dangerous Situation of the Ship in her Course from Trinity Bay to Endeavour River. Page 547.


An account of the incident was published in 1773 by John Hawkesworth in Volume 3, Chapter V, Dangerous Situation of the Ship in her Course from Trinity Bay to Endeavour River. Page 547.

First Voyage: An Account of the Voyages undertaken by the Order of His present Majesty for making Discoveries in the Southern Hemisphere… Volume 3‘. Edited from Cook’s journals by the writer John Hawkesworth. Printed for W. Strahan and T. Cadell; the Strand, London 1773.

‘…six of our guns, being all we had upon the deck, our iron and stone ballast, casks, hoop staves, oil jars, decayed stores, and many other things that lay in the way of heavier materials, were thrown overboard with the utmost expedition, every one exerting himself with an alacrity almost approaching to cheerfulness, without the least repining or discontent; yet the men were so far imprest with a sense of their situation, that not an oath was heard among them, the habit of profaneness, however strong, being instantly subdued, by the dread of incurring guilt when death seemed to be so near.’

Rediscovery and recovery

In 1969 an expedition for the Academy of Natural Sciences of Philadelphia arrived on the Great Barrier Reef with the dual purpose of finding the material jettisoned by Captain Cook on Endeavour Reef and collecting fish for study at that Academy and the American Museum of Natural History in New York City.  All six cannon along with several tons of iron and stone ballast were recovered and turned over to the Australian government for conservation and curation by the appropriate institutions.

The conservation was carried out by Dr. Colin Pearson at the Defence Standards Laboratory in Melbourne.  Dr. Pearson pioneered the treatment of iron objects recovered from the marine environment and went on to teach a generation of maritime archeological conservators.

After completion of the conservation treatment, then Prime Minister John Gorton decided to distribute the canons to the countries and states related to Captain Cook’s voyage. One canon was given to the Academy of Natural Sciences of Philadelphia; the Maritime Museum at Greenwich, England; the New Zealand government; the Queensland and New South Wales state governments and one was retained for the Commonwealth. After being on display in the Australian National Maritime Museum for over two decades, it can now be seen at the National Museum of Australia, Canberra.

After completion of the conservation treatment, then Prime Minister John Gorton decided to distribute the canons to the countries and states related to Captain Cook’s voyage.

Photo: Australian National Maritime Museum.

In April 2013 Silentworld Foundation acquired a substantial collection of maritime archaeological material from Ben Cropp who was an early diver/adventurer who went on to create his own small museum in Queensland.  Much of the material was recovered before the Historic Shipwrecks Act was in place.  However, all of the material was registered with the Commonwealth under an amnesty.

When the material came into the Silentworld Foundation collection it was realized that most of the objects needed remedial conservation treatment.  Among those artifacts were three pieces of iron ballast from the site of the Endeavour stranding.  This work was contracted out to a local conservation service.  When I joined the Foundation the ballast was still in treatment and, when the treatment was complete, it was my job to collect it.

Two pieces of ballast were In very good condition, however, one was significantly more deteriorated.

A piece of the Endeavour ballast in the Silentworld Foundation Collection. Image credit: Silentworld Foundation, 2021.

A piece of the Endeavour ballast in the Silentworld Foundation Collection. Image credit: Silentworld Foundation, 2021.

In fact, when that piece of ballast was picked up it broke into two pieces!  In a museum situation, this is normally a disastrous affair.  But in this case, the break revealed a fascinating discovery: Inside the cast ingot, we found round and intact cannonballs! The ballast had cracked at the junction of the well-preserved cannonball and the deteriorated cast-iron, as can be seen in the two images below. This discovery alludes to some interesting questions over the production of the ballast and the use of pig iron.

The cracked ballast, revealing cannonballs were added to the iron mixture at the time of manufacture. Image credit: Silentworld Foundation.

The cracked ballast, revealing cannonballs were added to the iron mixture at the time of manufacture. Image credit: Silentworld Foundation.

Further reading

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