One of the coolest things about Juneau Alaska is the extreme tides. On average tides here change 16-18 feet per day. Compare that to 4 foot tides on the Chesapeake Bay, for example.
I love when people use natural forces to accomplish things. The grid at the harbor in Juneau is one of those devices that do this. The first photo shows a large working boat, looks like about 50 feet long, lifted out of the water.
In this photo you can see the bow and the timbers, just at the water line, that it is resting on. This is the grid.
Here is another shot of the grid a few minutes later. Notice the tide has gone out more and the boat is now out of the water more.
Here is a view back down the grid showing the boat now fully out of the water. Captains tie up their vessels above the grid at high tide, and within a few hours the tide lowers the boat onto the timbers of the grid, exposing the underside of the boat. There is a window of 6-8 hours during which the hull can be inspected, scraped, cleaned and even painted, and the props can be worked on.
Isn't this ingenious?