Costly boiler repairs and the need to reduce the size of the Army Transport Service's Pacific fleet led to the ship's retirement as a troopship in 1902.

Grant was transferred to the United States Army Corps of Engineers and converted into a suction dredge in 1903.

She was responsible for widening and deepening shipping channels on the Columbia, Delaware, and Mississippi rivers, Hampton Roads, Tampa Bay, New York Harbor, and other major ports and waterways.

The Atlantic Transport Line commissioned four sister ships to be built by the Harland & Wolff shipyard in Belfast, Ireland.

[4] While the Atlantic Transport Line was controlled by American shipping magnate Bernard N. Baker, its operations were run from Britain.

[12] Noted race horse enthusiast Pierre Lorillard shipped a dozen thoroughbreds to London on board.

[13] In 1892 Mohawk carried Buffalo Bill's Wild West Show from London back to America.

In August 1892 she reached New York From London in 9 days, 20 hours, the fastest passage to that time by a freighter.

[15] Perhaps the most eventful day of Mohawk's career as a commercial vessel was 20 January 1897 when she saved the 17 surviving crew of the dismasted and sinking Norwegian bark Persia during a North Atlantic storm.

At the time, the United States had few overseas possessions, and thus its military had limited ocean-capable sealift to support such an offensive.

When the United States Army was able to begin acquiring ships after the declaration of war, fewer domestic options remained.

[4] Army Colonel Frank J. Hecker approached the Atlantic Transport Line to charter its fleet, and was refused.

He then offered to buy the vessels he sought and a deal was struck, subject to the approval of the Secretary of War Russell Alger.

In addition to Mohawk, the Atlantic Transport Line sold Massachusetts, Manitoba, Mobile, Michigan, Mississippi, and Minnewaska.

It was variously reported at the time that they were either replaced by Americans[18] or agreed to serve with a 20 percent increase in their wages.

[22] Having taken Cuba, Puerto Rico, Guam, and the Philippines, the Army had a permanent need for transport to overseas bases.

The Army Transport Service chose the best vessels acquired during the war to become a permanent sealift capability.

To mark their transition to permanent military service, they were renamed in January 1899 for prominent Civil War generals.

[34]As Grant backed out of her berth to begin her voyage on 17 January 1899, her starboard propeller fouled an old wire hawser.

On 18 January 1899 the ship sailed up the Hudson River to Grant's Tomb where a short ceremony was held to honor her namesake.

Grant and other Army Transport Service ships began a shuttle from San Francisco to Manila.

The civilian Governor of the Philippines, later U.S. President, William Howard Taft sailed home from Manila in December 1901 on Grant.

[62] The need for these costly repairs arose at the same time the Army was reducing its Pacific transport fleet as fighting in the Philippines and China decreased.

[63] The Army decided to retire Grant rather than pay for repairs, and offered the ship for sale in a sealed bid process.

[69] After a lengthy and contested bidding process, the contract for the conversion work was awarded to the Mare Island Naval Shipyard in February 1903.

During the same shipyard visit, tons of steel in her unneeded passenger cabins and superstructure were to be removed so as to give her a smaller draft, allowing her to work in shallower water.

[78] Another shipyard visit in 1914 added two 30-inch (760 mm) centrifugal pumps connected to drag arms 30 inches in diameter.

[86] She worked on this project intermittently from August 1919 to October 1925 during which time she removed 9,569,968 cubic yards (7,316,766 m3) of material.

[87] The ship spent much of the remainder of her career assigned to the Portsmouth, Virginia District of the Corps of Engineers and returned to the same channels and rivers multiple times to maintain water depth in the face of constant silting.

[101] The original ship's bell, forged for Mohawk, and which sailed on Grant and Chinook, is held by the US Army Corps of Engineers.