[1] In 1877 the Government of the colony of New South Wales ordered the construction of two "outrigger" torpedo boats, in response to concerns about a possible threat from foreign warships.

[2] The strange craft attracted much attention from the persons aboard the various yachts and steamers as she passed everything at a rate that made them seem to be comparatively standing still, even such boats and the Bellbird and Manly ferry steamers being relatively nowhere and being so small and low, the speed appears much greater than it would in a larger vesselNeither of the boats ever left the confines of Sydney Harbour, and they were never used in anger.

In the mid-1990s a workboat of the Royal Australian Navy detected a long thin hull with her side-scan sonar, which was thought to be the remains of Acheron.

Sold in 1902 and later acquired by an illegal German immigrant residing at Darling Point, Carl von Cosel Tanzler.

The modified Avernus washed aground on Double Bay beach[4] and in 1923 it was loaded onto a barge and taken to the Datchett Street Balmain Wharf ship breakers where it was scrapped.

[5] Twenty years later the eccentric Carl Von Cosel Tanzler had migrated to America and claimed to be an ex-submarine commander.