Dan Taylor, 65, a Navy torpedo man, engineer, inventor and restaurateur and one of the world's persistent dreamers, died July 23 at a hospital in Savannah, Ga., after surgery to correct an aortic aneurysm. In recent years, he was building a self-financed mini-submarine, complete with "biopsy wands," to prove the existence of the Loch Ness monster.

Although he never found the monster, Mr. Taylor had other memorable episodes. He built a giant aquarium and a windmill, the latter a 90-foot tower to power the Memphis restaurant he operated. He bought an old hydroelectric dam near Fayetteville, Tenn., hoping to return it to use.

When he later sold the dam, without getting it to operate, he remained sunny. "Nothing I make ever works the first time," he told a reporter.

He moved to Hilton Head, S.C., to care for his aging mother. There, he also reinvigorated his work as an amateur cryptozoologist, hunting for evidence of legendary creatures.

His fixation was the Loch Ness monster, that elusive freshwater serpent. He was almost certain the monster was a very large eel, based on what he had seen at Loch Ness when he took his first submarine there in 1969.

That first submarine, the Viperfish, malfunctioned in the murky Scottish loch. Some unusual currents that disturbed his craft, however, left him with the impression that "this might have been the monster saying hello."

His obsession was born, and he vowed to return some day. His effort took on new urgency after a debilitating heart attack and stroke a decade ago. "I see no other purpose for my life now but this expedition," he wrote in an online log of his work last year.

At his death, Mr. Taylor had invested hundreds of thousands of dollars building the new steel-structured sub that he named for a Celtic water goddess ("just a little extra insurance"). Working from a garage in Hardeeville, S.C., he designed the 44-foot-long machine to dive 2,000 feet, more than twice the depth of Loch Ness at its deepest. He kept no designs on paper, just in his head.

Mr. Taylor was not the only Loch Ness "monster hunter" since the craze to find "Nessie" was revived in the 1930s. And he was neither the most flamboyant nor the most credentialed. One such hunter, physicist-turned-lawyer Robert H. Rines, once journeyed to Scotland under the sponsorship of the New York Times.

Rines found Mr. Taylor a compatriot in the cause, telling a reporter a few years ago, "We need all the [Dans] we can get."

Dan Scott Taylor Jr. was born in Memphis on June 19, 1940. At age 7, he fixed empty five-gallon oil cans on his bike as makeshift pontoons and called the result a boat. He rode the bike to a nearby lake, and it sank.

"I learned a lot about ballast that day," he later told the Los Angeles Times.

After Navy service, he attended the Georgia Institute of Technology and held jobs at a fence company in Jacksonville, Fla., and then at a submarine works.

Mr. Taylor began building his first sub after reading a newspaper account about a planned expedition to find the Loch Ness monster. The story quoted a University of Chicago scientist named Roy P. Mackal, also a cryptozoologist.

He phoned Mackal and managed to become part of the trip. The Viperfish dived dozens of times over six months, and there were tense moments.

"It wasn't the monster, it was the leaks," he told the Scotsman newspaper. "My worst moment came when I was working on the hatch and got careless. Before I knew it, hundreds of gallons of water were cascading into the boat."

He began taking an umbrella aboard.

A decade ago, when he began his new ship in earnest, he let nothing deter him -- the titters of friends, especially his wife's friends, the probable cost, the physical labor involved. "My old man of the sea," his wife, retired schoolteacher Margaret Wade, once called him.

He sold his home in Memphis and began building his recent submarine, twice the size of the fiberglass Viperfish. His mother, a successful restaurateur, took in the couple, but she would not commit money to the project. "I helped him out on the first one," she told an Atlanta reporter. "But I told him no-go on this one -- he had to do it himself."

He got plenty of press but little interest from media moguls Ted Turner and Rupert Murdoch and author Tom Clancy, among those he wrote for backing. He called off his mission temporarily.

He received moral support and occasional "grunt work" help from Vicki Mudd, a biologist and environmental consultant who considered Mr. Taylor a genius and a mentor. "He thought the world was just a Tinker Toy set," Mudd said.

On his Web site, www.nessaexpedition.com, Mr. Taylor explained: "The most common question I am asked is, 'Why?' To this I say that after the first expedition I knew I could if I wanted to and if I was curious enough. . . . But, really, I think that it is truly the challenge of it all for me. We Americans are like that, you know."

Besides his wife, survivors include two sisters.

Inventor Dan Taylor last year inside his 44-foot submarine, designed to plumb the depths of Loch Ness in Scotland.