Information from "High Seas, High Risk" by Pat Wastell Norris, published by Harbour Publishing, and wikipedia

Nautical lore - SS Sudbury, ocean-going salvage tug

HMCS Sudbury was a Flower-class corvette that served the Royal Canadian Navy during the Second World War. She served primarily in the Battle of the Atlantic as a convoy escort. She was named for Sudbury, Ontario.

Corvettes commissioned by the Royal Canadian Navy during the Second World War were named after communities for the most part, to better represent the people who took part in building them. Sponsors were commonly associated with the community for which the ship was named. Royal Navy corvettes were designed as open sea escorts, while Canadian corvettes were developed for coastal auxiliary roles which was exemplified by their minesweeping gear. Eventually the Canadian corvettes would be modified to allow them to perform better on the open seas.
HMCS Sudbury was ordered in February 1940, laid down by Kingston Shipbuilding Ltd. at Kingston in January 1941,  launched in May and commissioned into the RCN in October 1941 at Montreal, Quebec. She was initially assigned to duties in the Western Atlantic where she served until  January after which she was reassigned to the Pacific coast and immediately underwent a major overhaul. After workups in May 1944, she joined Esquimalt Force and remained with them until the end of the war.
HMCS Sudbury was paid off at Esquimalt 28 August 1945. She was sold for civilian use as a 892 GRT tugboat and entered civilian service in 1949. The ship retained her name. Sudbury underwent several ownership changes until she was acquired in 1954 by Island Tug and Barge of Victoria, British Columbia.

Harold Elworthy started work as office boy, at the grandly-named Pacific Salvage Company, at the age of 16. Harold was alone in the office one Sunday when a message came into the office requesting assistance for a vessel in distress. Harold was unable to contact the Owner, Arthur Burdick, so he took it on himself, without the authority, to order out one of the company's tugs. When Mr. Burdick came into the office later in the day and learnt what Harold had done, he fired him. WHen Harold went into the office next day to clear out his desk Mr Burdick reversed his firing commenting that the salvage job the day before was the most profitable business he had ever done.
Later realising that he had no long term future with Pacific Salvage he approached the owners of the under-used tug  Quinitsa and proposed going into business with them. THus Island Tug and Barge was formed in February 1925 and Quinitsa was renamed Island Planet. THeir first job was towing a scowload of coal from Nanaimo. A year later Island Tug and Barge bought out Gardner Towing. In 1941, without Harold's knowledge his original employer, Arthur Burdick, bought Royal Trust's share of the business, reducing Harold from minority shareholder to manager. Not to be held back, Harold left Island Tug and Barge, formed a partnership with Stanley McKeen and created a new company, Straits Towing and Salvage Company. Harold was then competing with his former company, one in which he still held shares. In contrast, Burdick had a company he knew nothing about and couldn't run. Within a year Straits Towing in partnership with  Foss Towing of Seattle  bought Burdick out. Eventually Harold and Stanley ended their partnership. Harold took over Island and Stanley Straits. In 1952 Island bout the Young & Gore Towing Company.

By the mid-1950's Island Tug had 27 boats, ranging from small harbour tugs to ocean-going vessels, together with a full array of barges, scows, and salvage equipment. After the end of World War 2 he was part of a consortium which bought several surplus corvettes and sold HMCS Sudbury for conversion to a tug. At the same time, Harold and his sons reasoned that there would be a lot of Liberty-type merchant ships, which had been designed and built for a single crossing of the ocean, getting into distress and needing help. Consequently in 1954 Island Tug and Barge bought the Sudbury.

Sudbury and her crew specialized in deep-sea salvage and completed many dramatic operations. Their most daring rescue took place in November–December 1955 when they saved the Greek freighter Makedonia in the North Pacific. 
As described in 'High Seas, High Risk', the winter weather "that surrounds the Aleutian Islands is the worst in the hemisphere. During winter, storm follows storm in unending succession, the wind howling out of the north at 50-60 knots, bringing with it driving sleet and snow". Speed was gradually reduced as the weather got worse but waves continued to sweep over the Sudbury. 
Again from 'High Seas, High Risk', "Periodically a shower of salt water coming down a ventilator reminded them that all hell was breaking loose on deck, and eventually the amount of water they were taking down the ventilator could not be ignored. The engine room gang drew straws and Eddie lost. It fell to this youngest member of the group (still in his teens) to go up on deck and close the offending ventilator. Eddie was scared stiff. Nonetheless he headed up the companionways to the top deck and then, for ten minutes, struggled to open the door. FIghting against the wind and water that lashed at the other side of it, he finally got it open a few inches and began to squeeze through. He had one leg outside when the ship rolled onto her side and the steel door came back on him. Desperate now, terrified that he would be crushed, he heaved against the metal with all his strength and managed to free himself. Now in the maelstrom outside, he crouched, clutching a rail. The ventilator was six feet away; to reach it - to relinquish his grip on the rail and transfer it to the ventilator -took all the willpower he could muster. As the ship rolled, he chose his moment and grabbed the ventilator with both hands. As he did so he discovered with dismay that his feet were no longer under him but straight out behind. He was attached to the ventilator as a flag is attached to a mast. Somehow he regained his feet, turned the ventilator and fought his way back inside."
Sudbury towed the disabled vessel for 40 days through some of the roughest weather imaginable before arriving safely at Vancouver. The incident made headlines around the world and for the next decade Sudbury was one of the most famous tugs on the Pacific coast. 

Sudbury was involved in other vessel salvages. THe full story can be found in "HIgh Seas, High Risk" by Pat Wastell Norris.

Sudbury was eventually badly damaged, during repairs, by a boiler explosion, the fireman on watch having lingered too long in a quayside pub, and thus the hull was dismantled for scrap in 1966 at Victoria, British Columbia by Capitol Iron & Metals and officially stricken in 1967.