I think the tugs are simply turning the ship around. It is usual practice to use two tugs, one on the bow and the other on the stern to swing a ship in confined waters. Malted Falcon mentions that the ship was tested for stability after the Eastland disaster but I don't think that is what is happening in this picture. The tug with the bow line is not the same one in the picture of the test and I don't think they would do the stability test with all those people on board.

[No one has said the Shorpy photo is of the stability test. -tterrace]

Forty years ago I worked at Grangemouth Docks and often saw tugs doing their thing. It's a long time ago and few clear memories remain, but I've always thought it quite normal for tugs to work in pairs, one ahead and one astern of the larger vessel. The one ahead provides the main towing force while the other can act as a brake, and either/both can swing the ship around as required. Overall, two tugs allow much more control than one.

If they are doing the stability testing in the photo those sandbags along the rails sure look like passengers to me.

[No one has said the Shorpy photo is of the stability test. -tterrace]

Could it be that the tug on the stern line is turning the ship while the tug on the bow line is holding in place until the ship is headed in the correct position to be towed to the dock.

When in 1915 the SS Eastland capsized in while docked in the Chicago River with the loss of over 800 lives, officials subsequently ordered many passenger ships to undergo stability testing, which the Columbus passed easily. Even with 7,500 sandbags (simulating passengers) piled on one side, and tugboats pulling in that direction, she listed only 12 degrees. Below is a photo of the testing.

Any idea what's going on here? The Columbus is under tow at both ends (apparently moving sideways). I don't imagine that was routine.

Although several Steamships of the "Whaleback" style were built, The Christopher Columbus was the ONLY Passenger steamer of that design. Constructed in 1892-1893, it was exhibited at the Columbian Exposition in Chicago, and eventually scrapped in 1936.