Boatnerd Discussion Forum

Speaking of the spare lock gates for the U.S. locks, I believe the Corps of Engineers retrieved them last year to be scrapped.

[quote=guest post_id=272320 time=1739636651]
It has happened on the Canadian side where a ship rammed the lower lock gate. However the upper gate held back the lake Superior water. Same as lock 7 on the Welland canal. An up bound vessel would hit the cement sill, never the gate it self.there is an arrester cable lower in the down bound position that is suppose to stop a vessel. It's apparent it didn't work at the Canadian lock. It was in the early 19th century. Someone in boatnerd land probably has more in!
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The event took place, I believe, on June 9, 1909.

It has happened on the Canadian side where a ship rammed the lower lock gate. However the upper gate held back the lake Superior water. Same as lock 7 on the Welland canal. An up bound vessel would hit the cement sill, never the gate it self.there is an arrester cable lower in the down bound position that is suppose to stop a vessel. It's apparent it didn't work at the Canadian lock. It was in the early 19th century. Someone in boatnerd land probably has more in!

There has been precedence where a ship did damage the lock gates at the Soo. That incident occurred at the Canadian Lock after the Percy G. Walker collided with the lower level lock gates while the upper level gates were still open. In the Canadian lock case, there was and still is a "swing dam" that could/can be swung into place across the upper level channel near the railway bridge. Spare gates are kept underwater near the lock.
https://industrialscenery.blogspot.com/2021/06/the-canadian-lock-and-emergency-swing.html

The U.S. Soo locks have spare gates kept in the St. Marys river (Lake Munuscong?), ready to be retrieved if a damaged lock gate needed to be replaced. The Poe and MacArthur Locks use stop logs (steel construction) and are dropped into a channel upstream from the upper gates. They are used every Winter for de-watering the locks for repairs or in case of an emergency. This gives a good view of the stop log at the far left of the picture: https://www.sooleader.com/local-news/macarthur-locks-closing-for-seasonal-repairs-maintenance-6252369

The locks are designed so that water pressure on the Lake Superior side holds the gates shut. If you look at an aerial photo of the locks, you’ll see the gates form a “V” shape… pointing in the “upstream” direction. They don’t rely on a mechanical latch to stay shut. Water pressure does the work. The greater the pressure, the tighter they stay shut. It would be extremely difficult (perhaps even impossible) to open a gate before the water pressure has equalized on both sides.

The design of the locks is truly an elegant example of engineering, using water pressure and gravity to do 99% of the work.

If memory serves me, I think many years ago, the [b]Perry G. Walker[/b] ([i]NOTE: I could be wrong![/i]) was in, I believe, the Canadian lock at the Soo, when the downbound gates let go. At the time, I think the upper gate was open, and from pictures of the day, the torrent of water downstream was incredible. Overall, it would be quite a mess, I'm sure.

The Soo locks are not dams. They offer a channel for a vessel to be lowered in a safe manner up or downstream. The St. Mary's River flows around the locks into the white rapids beneath them. Any effect would be negligible.

I'm curious if anyone knows of any contingencies for if a Lake Superior side gate were to fail. I'm talking about suddenly without being able to close off the other end. That would be catastrophic for the shoreline downstream. How would they stop the water? Or any other lock in the system for that matter...