ALAMEDA — Late last year, more than three dozen harbor seals lounging on a crumbling, wooden dock threatened to derail progress on a new $50 million ferry maintenance facility at the former Alameda Naval Air Station.

But an innovative idea to replace that favored seal sunning spot with a specially built floating platform nearby appears to have done the trick. The notoriously skittish creatures seem pleased with their $68,000 upgrade from the Water Emergency Transportation Authority, which manages ferry service on the bay, and the groundbreaking for the new facility is on track for later this month.

“For a while, the seals were looking at it, and we didn’t know if they were actually going to climb up on it,” said Richard Bangert, an Alameda resident who checks on the seals almost daily. “But then they were quickly using it.”

On a recent afternoon three seals shared the new platform with about a dozen seabirds.

Bangert was pleased because during the summer spotting a seal is hit or miss. It’s more likely during the winter, when the bay is colder and the seals seek opportunities to warm themselves in the sunlight.

On Christmas Day in 2015 enthusiasts counted 38 seals on the now-removed wooden dock, which was located near Ferry Point and West Hornet Avenue.

The new concrete and Styrofoam platform, 20 feet by 25 feet, was installed July 11 adjacent to the old dock and floats about 100 yards from shore.

Harbor seals are typically silver with gray, black or reddish spots. They do not have ear flaps, which are characteristic of the California sea lions that lounge before tourists at San Francisco’s Fisherman’s Wharf. Harbor seals are also distinctive in that they wriggle on their bellies on land, whereas sea lions “walk” using their large front flippers.

Harbor seals are so shy they will sometimes scamper back into the water when people are hundreds of feet away, and they have been known to abandon pups as they seek safety. Kayakers are especially likely to spook harbor seals, perhaps because they skim the water’s surface, said Mark Klein, a former volunteer at the Marine Mammal Center in Sausalito.

Like Bangert, Klein looks in on the seals daily using binoculars, and he records how many are on the platform and the times they show up.

“That’s what helps make this place special,” said the 71-year-old Alameda resident, who became interested in the bay’s wildlife after he retired as a computer technician with AT&T. “The seals are not afraid and yet they’re still close to shore.”

What also makes the Alameda location unique, he said, is that it’s one of two spots where seals “haul out” on the bay’s eastern edge. The other is in Fremont.

Over the next few weeks crews will move the new platform in phases until it’s about 900 feet south from where the old dock once jutted into the bay.

The idea is to protect the seals when WETA breaks ground later this month on the $50 million ferry maintenance facility planned for the site, which is near the USS Hornet Sea, Air & Space Museum. It will have berthing space for 12 vessels, as well as an emergency operations center that WETA will use to coordinate regional relief efforts after a major earthquake.

The announcement that the ferry authority was planning to tear out the wooden dock, which had partly collapsed into the bay, prompted local residents to rally to protect the seals, a campaign that resulted in the agency providing the platform.

“The platform is the only one of its kind that we know of,” said Jeff DelBono, a WETA board member. “It was custom-built. And so far, so good. The seals love it.”

Harbor seal haul-outs dot the Pacific Coast from the Bering Sea to Baja California. While the seals gather in Alameda and Fremont, their largest population in Northern California is at Marin County’s Point Reyes National Seashore, according to the U.S. National Park Service. Their overall population in California is about 35,000.

Bangert hopes similar floating platforms can be used in other gathering spots for seals that may be threatened.

“Unless there is some issue or problem, seals will haul out at the same site year after year, which is what we want,” he said. “We want them to stay here.”

Reach Peter Hegarty at 510-748-1654 or follow him at Twitter.com/Peter_Hegarty.