Their era ended in 1977 when President Jimmy Carter, seeking to end what he called the “imperial presidency,” sold the last of them, USS Sequoia, a yacht used by every president since Franklin Roosevelt.

Once on board, American chief executives cruised from Maine to the Caribbean, explored the Potomac and Chesapeake Bay, reviewed the fleet, received royalty, conferred with allies, thought through future plans—or just loafed, played poker, or went fishing.

Theodore Roosevelt used the 273-foot Mayflower as an instrument of personal diplomacy in the 1905 negotiations that ended the Russo-Japanese War and earned him the Nobel Peace Prize.

Woodrow Wilson, a White House widower, courted Edith Bolling Galt aboard Mayflower. During World War I, Wilson used the yacht to escape “people and their intolerable excitements and demands.”

In the months before the United States entered World War II, Franklin Roosevelt deployed Potomac in a nautical shell game to cloak a secret rendezvous at sea with British Prime Minister Winston Churchill.

Harry S. Truman found Williamsburg a pleasant setting for an afternoon nap or a convivial game of poker, but was far less happy when she bucked and pitched in the open ocean. Williamsburg supported Truman’s 11 vacations at Key West, Florida, serving as a communications center and providing cabins for the president’s overnight guests.

Under siege during the Watergate scandal in the late summer of 1974, Richard M. Nixon boarded the Sequoia, cruised on the Potomac and pondered resigning rather than face impeachment. But the seclusion he sought proved an illusion. “When we passed under the bridges, reporters and photographers would suddenly surge forward hanging perilously over the railings, trying to get a closer glimpse or a closer picture,” Nixon recalled.

“We were the subject of a deathwatch,” his daughter Julie concluded. “Being on the Sequoia was like bobbing along in a glass bottle.”

John F. Kennedy’s hours on the water were far less stressful. Here’s an account from Kennedy aide Theodore Sorensen:

“On board either the family or the presidential cruiser the president read history or biography or fiction, chatted with family and friends, waved at passing boats, watched local sailing races and enjoyed the distance between himself and the Secret Service” who trailed him on an escort vessel.

Grandest of them all, Mayflower was manned by eight officers and 166 men, including musicians. Its reception rooms were paneled in white and gold. The dining table sat thirty.

William Howard Taft’s wife, Helen, verged on the poetic as she described the yacht’s cruise along the Maine coast in the summer of 1910. In a memoir she drew a word portrait of “the Mayflower steaming among the crags and rocks of the broken, picturesque coast, or lying at anchor in some quiet harbor with only the soft water sounds to break the stillness.”

“I know of no other way for (a president) to get short intervals of rest than by boarding the presidential yacht and steaming away out of the reach of crowds,” she said in a memoir. "Mayflower," she said, would work well for any American president, “if he happens to be a good sailor.”

Years later, President Calvin Coolidge, decidedly queasy after a long afternoon in rolling seas reviewing passing battleships, sank, grim-lipped, into a Mayflower deck chair and managed a final salute, the fingers of his right hand touching his favorite yachting cap. A photographer chose that moment to snap a picture.

In March 1941, Franklin Roosevelt leaned into a radio microphone on board Potomac after a cruise in Florida’s Gulf Stream. He told his audience that a short escape to salt water offered “a chance for a bit of sunshine or a wetted line, or a biography or a detective story or a nap after lunch.”

But above all, he said, a cruise out of sight of land, provides a president an important opportunity “for thinking things through,” for sifting through all that lies ahead and deciding what is important and what is not.