Blasting Seymour
Before 1958, Seymour Narrows, the narrowest part of the Inside Passage, about a hundred miles north of Vancouver, was a place all mariners feared and through which almost all traffic to Alaska had to pass.
An underwater rock lurked right in the middle, creating large and powerful whirlpools when the tide was running at strength. The whirlpools were large enough to pull good sized fishboats under and strong enough to push even a large ship against the rock.
Safe passage was only possible at the slack water period at high or low tide. For big ships, this was the only sheltered route north to Alaska, and as they got bigger, “Old Rip” became more and more of a hazard.
Finally in 1942 a serious attempt was made to blast the rock with a barge anchored with six 150-ton cement anchors. But the current was too strong and the cables and anchors couldn’t keep the barge stationary long enough for dependable drilling, and the strain broke the thick steel cables on the average of one every 48 hours. The final straw was when a work boat flipped in the current, drowning the crew and the drilling barge approach was abandoned.
Finally a huge drilling project was undertaken - over 3200’ of tunnels and vertical shafts - reaching down from a nearby island, under the channel and up into the interior of the rock. This was before the sophisticated sort of surveying equipment that we take for granted today was available, and drillers would explore with small diameter drills - until they broke through to the water. Then they’d plug the hole and use the information to create a 3D map of the rock and the water around it. They tried to keep 30’ of solid rock between the area they were blasting and the water, lest a breakthrough drown the work crew and flood the project.
Finally tugs pushed barge loads of dynamite - 2.8 million pounds of it - to load into the cavern they had excavated, and on April 5, 1958: adios Ripple Rock!
The currents and whirlpools are still hazardous to small craft whose skippers choose not to wait until slack water, but the rock itself is under 45 feet of water instead of 9.
And as the Alaska Cruise fleet continues to grow, Saturday and Sunday nights present a challenge at Seymour.
As on a busy night, five southbound and five northbound ships try to fit in the 30-minute slack water safe passage window.
And in addition to the cruise ships, there are fishboats, tugs, yachts, etc.
So even if your ship goes through Seymour at night, stay up for it!
Video of Georgia Straits and Ripple Rock blast: http://youtu.be/ibzdawCcx_o
