City lifeguards helped a man to shore Sunday after he and another man were spotted atop a sailboat sinking just off the Outrigger Canoe Club in Waikiki.
The second man rowed ashore and then disappeared, club members said.
Coast Guard Lt. Leigh Cotterell said pollution investigators inspected the boat before and after it sank and determined it poses no environmental or safety hazard.
He said the case was turned over to the state Department of Natural Resources.
"This is really a state issue," Cotterell said. "Whatever the state decides is the best resolution."
DLNR officials were unavailable Sunday for comment.
Employees at the Elks Club said the vessel had been left in the same spot, unattended but still afloat, since at least Wednesday.
An Outrigger employee said the two men, presumably operators of the single-masted boat, used a small rowboat to reach shore Thursday and were seen that night asking people at the club for food and sleeping on the beach.
Leilani Shaw said the men were not seen again by club members or employees until Sunday, when the pair took the rowboat that they left on the beach back to the sailboat and boarded it.
"This whole thing is so fishy," Shaw said. "It’s like floating fine, floating fine, and they go out to it and boom! It sinks quick."
Shaw said one of the club’s members paddled out to the boat just after it sank around 10:45 a.m. Sunday to remove some surrounding debris and two 6-gallon fuel tanks, only one of which had fuel.
Debbie Millikan, a Diamond Head resident who watched the boat floating offshore for days, said she is upset that the state would allow the boat to be anchored so close to the reef for so long, especially with fuel tanks on it.
"We saw it on Friday afternoon at low tide, definitely grounded on the reef," Millikan said. "The question is, well, Why wasn’t it taken off before it sunk? We feel it’s a waste of resources and time and all the rest of it (work) that’s going to go into it now."
Millikan described the boat as a "nice" 30-foot sailboat anchored perhaps 300 or 400 feet offshore. She said she swam out to it with her husband, and they noticed sails all over the deck and fenders still hanging on the hull.
"It’s maddening," she said. "It’s a waste."
Millikan said her husband reported the vessel to the Coast Guard, Honolulu Fire Department and DLNR’s investigations division.
Shaw said she saw the two men boarding the vessel Sunday morning, and when she looked back again she noticed it was sinking. The hull went under within 15 to 25 minutes, she said.
The mast was still visible above water later in the day.
While lifeguards assisted one of the men off the boat, the other paddled back in the small rowboat, and when he reached shore he "took off," she said.
"It’s just, like, so suspect," she said.