Shamrock

The wreck of the Shamrock consists of the remains of a wooden steam powered tug located off the southwest corner of Vivian Island, which is north of Texada Island in the Algerine Passage of British Columbia. The wreckage of the vessel lies on a slopping rock and sand seabed, oriented along a bearing of 048 degrees true bow to stern in approximately 8 to 14 metres of water. The wooden structure of the Shamrock is gone, but much of her equipment, including its steeple steam engine and water tube boiler lie on the bottom where it fell.

British Columbia's Heritage Conservation Act automatically protects all heritage wrecks, including the remains of all wrecked vessels and aircraft once two or more years have passed since the date of loss. It is illegal to damage, alter or remove a heritage object from a heritage wreck except under a permit issued by the Archaeology Branch.

The heritage value of the Shamrock lies in the fact that this wreck contains the only known extant example of a steeple steam engine underwater in B.C. The Shamrock was a single screw vessel driven by an upright compound steam engine built by Cridiford and Company in 1877. In a steeple compound engine the cylinders are arranged vertically one above the other on a common axis with both pistons mounted on the same rod and moving together. The exhaust of the high-pressure cylinder feeds the low-pressure cylinder. The steeple arrangement required a high ceiling to the engine room, but the advantage is that it took up less floor space than a horizontal engine and it also required less complex masonry foundations beneath the engine, freeing up cargo room. The two-cylinder engine is believed to have produced 150 horsepower.

The Shamrock was also important in that according to Major Mathews, the first Vancouver City archivist, the tug was considered to be the first steamer built in the City of Vancouver. Launched as the Mamie, Shamrock was built at the Leamy & Kyle Sawmill on False Creek in Vancouver by John F.T. Mitchell of Seattle. The vessel was 76 feet long, 19 feet wide and 7 feet deep. The Mamie changed owners several times over her working life which was primarily spent towing log booms and scows along the southern B.C. Coast. James S. Emerson, a logger of Vancouver, bought the tug on June 4, 1904 and renamed the vessel Shamrock. The vessel struck Vivian Island and sank on December 8, 1926.

The vessel's wreckage makes it an excellent example of late 19th century steam technology that was widely used on the B.C. coast and was instrumental in the development of the local economy well into the 20th century. Its relatively shallow depth makes it accessible to recreational divers with an interest in local history.

The character-defining elements of the Shamrock include:

- Compound steeple steam engine

- Remains of its water tube boiler

- 2.3 meter diameter Iron propeller

- Furnace bricks

- Additional pieces of equipment including a tow bit and life boat davit