A treasure hunter on Cape Cod brought more booty ashore from a sunken pirate ship, including two cannons first identified by John F. Kennedy Jr.

Barry Clifford recently recovered new artifacts from the Whydah (WIH'-dah), a pirate ship that historians say sank in a fierce storm in 1717.

Kennedy was the first to spot the cannons on a dive to the shipwreck off Wellfleet, Clifford said, but archaeologists at the time brushed him off.. The former president's son even drew pictures of the cannons.

Clifford first dove with Kennedy off Martha's Vineyard in 1979 and 1980, before the pair became interested in the Whydah. The ship was discovered in 1984, according to the Whydah Museum in Provincetown.

Divers in 2007 found a weathered, plastic compass with the initials "J.F.K." attached to a cannon, Clifford said. The compass must have ripped off Kennedy's diving suit more than 20 years ago, he said.

Kennedy dove off and on near the shipwreck until his death in a plane crash in 1999.

The newly recovered cannons — one weighing about 1,500 pounds, the other 2,000 — have several pistols and other treasures corroded to their sides.

Historians say the ship ransacked more than 50 other ships in the 1700s.

"Anything of any value at all, they took," Clifford said. "It's like finding a department store on a shipwreck from the 18th century."

Rough weather and heavy sand deposits have made it difficult for divers to recover the rest of the treasure on the pirate ship.

The booty is stowed at Clifford's laboratory, the Whydah Museum and a traveling exhibition at The Field Museum in Chicago.