Richard Olin’s “El Dorado” was more than a 50-foot wooden boat. It was home.

And as crews worked to raise the vessel and contain fuel Wednesday, bystanders likened the boat’s sinking to a house being destroyed by fire.

Nobody — not the owner, not the Coast Guard — was sure Wednesday morning why the El Dorado sank Tuesday about 3:30 p.m. at the Port of Friday Harbor breakwater dock. Olin and his wife, who live aboard the boat, had been on the mainland for two days. Olin said he left a couple of forward windows open for ventilation, but other than that the boat had been secure.

Julie Knight of Islands Oil Spill Association said the El Dorado had about 100 gallons of diesel and 12 to 15 gallons of engine oil onboard when the boat slipped beneath the surface. A containment boom and absorbent pads were capturing much of the escaped fuel, although a sheen was visible outside the containment area. By 9 a.m. Wednesday, Knight estimated that about 25 gallons of fuel had been captured.

Coast Guard Petty Officer Todd Manow said civil penalties could apply under the federal Water Control Pollution Act, depending on how much fuel escaped into the water.

Harbormaster Tami Hayes said a liveaboard called the marina office about 3:30 p.m. Tuesday and reported that a boat at the end of the breakwater dock looked about a foot low. A few minutes later, the same person called back and said the boat was “going down.”

Hayes said she called 9-1-1 and Vessel Assist. Port workers immediately boomed off the area around the boat. IOSA’s Knight and the Department of Ecology’s Carl Anderson arrived later that afternoon and monitored the scene.

The El Dorado’s portside lines, tied to the breakwater dock bullrails, kept the boat from completely sinking into the 50-foot depth.

“I can’t remember when a vessel this size sank in the marina,” Hayes said, noting it’s the fourth or fifth sinking in the marina in 10 years.

Wednesday morning, as IOSA volunteers replaced fuel-soaked absorbent pads, divers placed canvas straps around the hull to stabilize the vessel. Inflatable bags would be placed in the boat next to buoy it, and then water would be pumped from the vessel. Ultimately, the vessel will be towed and removed from the water.

Olin, a retired yacht broker, said the boat is in good shape and he expected she could be restored and made seaworthy again.

“She’s the last of the woodies,” he said of the 1971 Trojan. “If she was fiberglass, she would be on the bottom by now.”