There are three references to singing on board the "Julia Ann". They all come from the final voyage that began in Sydney and ended in shipwreck. There were twenty-eight Mormons on board sailing for San Francisco. They were the ones who did the singing. Here is a quote from John Devitry-Smith's paper on "The Wreck of the Julia Ann", which you can find here:

http://allenhackworth.com/McCarthy/byujuliaann1.htm   (The quotes come from Part 2)

"After a final farewell from the Saints in Sydney, the Julia Ann with fifty-six souls and a 350-ton load of coal left Sydney Heads at 2:00 P.M., 7 September 1855, bound for San Francisco.26 As the voyage began, the passengers gathered between the poop and steerage house to sing "The Gallant Ship Is Under Weigh," but the thought of leaving friends and familiar surroundings for an uncertain future made the departure a more solemn occasion than joyous for many."

"Meetings were held regularly, and at night there was singing and prayer. After twenty-six days at sea, the Julia Ann continued "getting on with good wind," and aside from seasickness the voyage was a complete success with talk of soon arriving in San Francisco."

"Peter Penfold and others were singing on top of the midship house at the time of impact and, finding it too dangerous where they were, headed for the cabin. According to Penfold, "[T]he sea [was] breaking over us every moment, so that it was a thing impossible to stand."

It would be interesting to know what Peter Penfold and his friends were singing when the "Julia Ann" crashed into the reef. These references all come from eye witness Mormon accounts and not from Captain Pond.