J. Welles Henderson, 86, a lawyer whose fascination with life on the open sea led to his founding the Independence Seaport Museum, died of prostate cancer May 5 at home in Haverford.

When he was 7, Mr. Henderson received a small wood-and-metal anchor made from pieces of the USS Constitution in return for a 50-cent donation to save the historic frigate.

"It was as if I was inoculated with seawater," he later wrote. For the next 70 years he collected nautical artifacts and paintings, including a work by Thomas Birch - depicting the battle between the U.S. frigate United States and the British frigate Macedonian - that President John F. Kennedy displayed in the Oval Office.

In 1961, Mr Henderson launched the Philadelphia Maritime Museum with his collection in a rented room in the Athenaeum on Washington Square. It moved twice before settling at Penn's Landing in 1995 and taking on a new name: the Independence Seaport Museum.

On the day it was dedicated, Mr. Henderson, resplendent in white ducks, blue blazer, and red tie decorated with sailing knots, led a parade of city officials, Mummers, mermaids, and dancing blowfish to the new location.

Theodore Newbold, acting president of the Independence Seaport Museum, said Mr. Henderson could persuade people to write checks and donate precious heirlooms to the museum.

"Welles' passion would wear off on you," he said. "He was so compelling. He had a vision that Philadelphia's maritime history had been forgotten, and he wanted to share that history with the community."

Growing up in Germantown, Mr. Henderson was fascinated by stories his father, Joseph, a maritime lawyer, told of ships that had collided or caught fire at sea.

In 1928, he accompanied his father on a voyage to South America. During boring days at sea, he befriended the sailors, who let him polish the brass and allowed him up on the bridge when the ship went through the Panama Canal.

He graduated from St. George's School in Newport, R.I., in 1939 and entered Princeton University. He had summer jobs driving trucks along the waterfront in Philadelphia and worked as a longshoreman.

In 1943, he earned a bachelor's degree from Princeton and married Helen Lipscom, with whom he had a son, Joseph III. The couple later divorced, and she died in the 1970s.

During World War II, he served in the Army in Italy. He would have preferred the Navy, his family said, but Princeton did not have a Navy ROTC program.

He earned a law degree from Harvard University in 1949, the year he married Hannah Lowell Bradley.

The couple settled on the Main Line, and Mr. Henderson joined his father's firm in Philadelphia, Rawle & Henderson. He later joined Palmer, Biezup & Henderson.

The museum was born during the young lawyer's lunch hours.

Mr. Henderson would scour junk shops for items to add to his collection, his wife said. He also visited maritime museums around the world and became frustrated, he told a reporter in 1999, that unlike many cities in New England, Philadelphia had no museum to honor its maritime history.

By the 1950s, Mr. Henderson began to develop plans for a museum. He was encouraged by his wife, who told him that he would have to do something with his prints, logbooks, carvings and naval uniforms besides stuffing them under their beds and into closets in their home in Gladwyne. Initially, he served as museum president. Later he chaired its board. He became chairman emeritus in 1990.

Today, the museum has hundreds of artifacts, interactive exhibits, and two vessels on display: the Olympia, Adm. George Dewey's flagship during the Spanish-American War, and the Becuna, a World War II-era submarine.

In the 1990s, Mr. Henderson and Rodney P. Carlisle wrote Jack Tar: A Sailor's Life 1750-1910. The book detailed the lives of ordinary sailors during the days of the British empire, rugged lives that included bad food, disease and severe punishment.

Though in failing health in recent years, Mr. Henderson continued to enjoy opera and orchestra performances, his wife said, as well as time with his children and grandchildren at the family's summer home in Manchester-by-the-Sea, Mass.

In addition to his wife and son Joseph III, Mr. Henderson is survived by sons G.L. Cabot Henderson, T. Handasyd P. Henderson, and David Henderson; a daughter, Elizabeth Henderson; eight grandchildren; and one great-grandchild.

Funeral and burial were private. A memorial service will be held in the fall.