Seymour Narrows

Seymour Narrows is a 5 km (3 mile) section of the Discovery Passage in British Columbia known for strong tidal currents. [BCGNIS|15307|Seymour Narrows] Discovery Passage lies between Vancouver Island and Quadra Island except at its northern end where the eastern shoreline is Sonora Island. The section known as Seymour Narrows begins about 18 km (11.5 miles) from the south end of Discovery Passage where it enters the Georgia Strait near Campbell River. For most of the length of the narrows, the channel is about 750 meters wide. Through this narrow channel, currents can reach 15 kn.

Seymour Narrows was described by Captain George Vancouver as "one of the vilest stretches of water in the world." [ [http://archives.cbc.ca/IDC-1-75-657-3654-20/that_was_then/science_technology/ripple_rock_blasted B.C.'s deadly Ripple Rock blown up, CBC Broadcast Date: April 5, 1958] ] Even after Ripple Rock was removed, it remains a challenging route. In March of 1981, the Star Philippine, a freighter ran aground in the narrows.

Seymour Narrows is notable also because the flowing current can be as turbulent as to realize a Reynolds number of about $10^9$, i.e. one billion, which is possibly the largest Reynolds number regularly attained in natural water channels on Earth (the current speed is about 8 m/s, the nominal depth about 100 m). Turbulence develops usually around a Reynolds number of 2000, depending on the geometric structure of the channel.

Ripple Rock

Ripple Rock was a submerged twin-peak mountain that lay just nine feet beneath the surface of Seymour Narrows. It was a serious hazard to shipping, sinking 119 vessels and taking 114 lives. The gunboat USS "Saranac" was one of the rock's first recorded victims. On April 5 1958, after twenty-seven months of tunneling and engineering work, Ripple Rock was blown up with 1,375 tons of Nitramex 2H explosive making it the largest commercial, non-nuclear blast in North America.

The event was broadcast live on Canadian Television. The footage is also regularly screened at the Campbell River Museum.

Vancouver band The Evaporators wrote a song about the event and released it on their 2004 album "Ripple Rock".

References

Canadian Tide and Current Tables, Vol. 6, 2003

External links

* [http://www.vancouverislandabound.com/tamingof.htm Overview of Seymour Narrows]
* [http://www.vancouverislandabound.com/tamingof.htm Ripple Rock Explosion, Vancouver Island]
* [http://archives.cbc.ca/IDC-1-75-657-3654-20/that_was_then/science_technology/ripple_rock_blasted Ripple Rock blown up - Unforgettable Moments - CBC Archives] (Video)
* [http://www.northislandlinks.com/campbell_river/archives/oldsites/98site04/site.htm Campbell River Site - Ripple Rock]
* [http://www.crmuseum.ca/ Campbell River Museum official website]
* "Freighter Aground in Canada", in the New York Times, March 18, 1981