The C-class ferries (also known as Cowichan class) are a class of five double-ended roll-on/roll-off ferries operated by BC Ferries in the Strait of Georgia in British Columbia, all constructed between 1976 and 1981. When the vessels were first built, they were the largest ships of their kind in the world. The C-class ferries are long, with a car capacity of 362, and a crew and passenger capacity of 1500 persons. Each vessel's two MaK 12M551AK engines produce 11,860 HP, which provides a service speed of 22 knots. C-class vessels The first two C-class ferries were Queen of Coquitlam and Queen of Cowichan, constructed in 1976. Queen of Oak Bay and Queen of Surrey were built in 1981. There were some minor modifications to the design of the two later ships compared to the earlier C-class ships; most noticeably, Queen of Oak Bay and Queen of Surrey both have longer passenger decks than their older sisters. The C-class vessels were designed by Philip F. Spaulding and are similar to the Jumbo-class ferries he designed for Washington State Ferries several years earlier. Queen of Alberni was also constructed in 1976 along with the first two C-class vessels. Although this ferry is considered to be a C-class vessel, it is significantly different in layout. It was originally designed to carry only overheight (truck) traffic but in 1984, an upper car deck was installed for 150 non-overheight vehicles. This ferry has a capacity of 292 cars and 800 passengers and crew, and has a maximum service speed of . Queen of Coquitlam, Queen of Cowichan, Queen of Oak Bay, and Queen of Surrey each received extensive mid-life upgrades in 2003, 2004, 2005, and 2006 respectively. Queen of Alberni also received a similar upgrade in 2007. From engine work to major modifications and improvements, the vessels were refitted to provide an additional 20 years of service. In July 2018, BC Ferries announced that it had issued a request for proposals to build replacement vessels for all C-class ships, with deliveries beginning in 2024. Routes C-class ferries are double-ended; they have a separate bridge at each end and therefore are not required to turn around during the sailing. These ferries generally run on the Duke Point–Tsawwassen, Horseshoe Bay–Departure Bay and Horseshoe Bay–Langdale routes. At one time, these ferries operated on the Swartz Bay–Tsawwassen route, but due to limitations placed on their speed when transiting Active