He knows every one of her nail holes. She came to him a rusted wreck 10 years ago and now her fresh grey hull is wet with rain, as she's loaded on a barge and carried above the wash of Sydney Harbour. "It's too important to go back in the water," Mr Glasson says.

He likes sailing boats but is no sailor. "I like tug boats. I like work boats. The sad bit is I have only got an interest in the boats no one notices, no one sees. They're invisible. They come and do the essential jobs and then they're gone."

Mr Glasson, 49, has thick square glasses, a slight stoop and lopsided smile. He has a licence to drive boats but not a car. Each day before dawn, he chugs his own century-old wooden dog boat about the harbour, looking for lost and forgotten things.

Matilda came along in 2006, a basket case of a boat that some people told him to bin. She had long been neglected, after serving as a motorboat for transferring personnel on HMAS Parramatta, one of the Royal Australian Navy's torpedo boats, during World War I.

She's a special little boat, Mr Glasson says. Surprisingly light and slender but longer – 6.6 metres in all – than she looks in a shed on Spectacle Island, a little-known former Navy armaments depot near Drummoyne.

The shed smells of sawdust, turps and varnish. Abba's on the radio singing Take a Chance on Me. Along the walls are two dummy missiles and an aged torpedo. "They're not live or anything," he says.

Mr Glasson and his fellow volunteers for the Naval Heritage Collection rebuilt Matilda from scratch: hanging her from the ceiling for two years to pull her hull back into shape, replacing the ribs and deck with Burmese teak, sizing nails to fit her original nail holes. Working sometimes seven days a week, 14 hours a day. "It's too special a thing to let fall through the cracks," he says.

He hands out biscuits as Matilda is hoisted by a crane onto a barge and carried across the water to the National Maritime Museum, past towers of concrete and steel, for the Classic & Wooden Boat Festival, from April 15 to 17.

Chronic asthma kept him out of the navy. Instead, he's spent decades working the early shift in boatyards or on bridges and slipways. "When I worked at Glebe Island you would see the tugs lined up at 3.30am for the first bridge opening. They come and go, and no one sees them. And to me that's sad," he says.

"It's like everyone sees a shiny boat in a shed but no one remembers the team of blokes that worked on it."