The two companies seeking to launch seaplane service in Boston Harbor say their first flight tests in the harbor took place this week without any significant hitch, in or over the water.

But they’re still going to face some turbulence — on land.

Three politicians who represent South Boston are raising concerns about the effect on their neighborhood’s northern waterfront, citing the amphibious planes’ noise and potential navigation hazards.

Executives from the two companies — Tailwind and Cape Air — say they hope to allay those concerns by meeting with local leaders and familiarizing them with the planes, which the companies want to fly between Boston and a landing area at 23rd Street in Manhattan.

The Federal Aviation Administration will decide whether these companies can offer regular service in and out of the harbor, and FAA officials declined to say how the tests went this week. Cape Air’s test took place Tuesday, while Tailwind flew Wednesday.

Still, the elected officials who expressed concerns — City Councilor Michael Flaherty, state Representative Nick Collins, and state Senator Linda Dorcena Forry — could influence the FAA’s decision-making and how Mayor Martin J. Walsh’s administration handles the seaplanes’ arrival.

Flaherty said the Charles River is a much better place to land than Boston Harbor. He said the unpredictable wind patterns over the harbor and the intense boat traffic during the warmer months raise questions about seaplanes’ safety.

“It’s a bad idea and a recipe for disaster,’’ Flaherty said.

Collins mentioned the possibility of security risks because passengers wouldn’t be screened like travelers at Logan Airport. He argued that Logan is a better spot for seaplane flights because it is more secure and not far from the city center.

“Does the public need outweigh the associated risks and costs?’’ Collins said. “I don’t think so.’’

The motivation is simple: There’s money to be made from people willing to pay about $1,000 roundtrip from Boston’s waterfront to Manhattan’s — about the same as the cost of a walkup ticket on the Delta and American shuttles — to avoid the hassles of airport travel.

The trip would take under 90 minutes, far faster than an airplane, train, or car.

Both Tailwind, a charter service, and Cape Air, a more established airline, have been developing the seaplane service for at least two years and might launch commercial routes between New York’s East River and Boston Harbor within a year. The companies have some experience with seaplanes: Tailwind handles some flights from Manhattan to the Hamptons, while Cape Air in January started service between Florida and the Bahamas.

Cape Air had its inaugural test flight Tuesday. The main goals, senior vice president Andrew Bonney said, were to assess the companies’ approach and departure routes, familiarize the Coast Guard and the city’s harbormaster with the plane, and study whether the noise levels would be compatible with the community. The test, Bonney said, exceeded expectations on all three fronts.

Cape Air also tested taxiing the plane, a nine-passenger Cessna Caravan, through the water to dock at Pier 4 on the South Boston waterfront. Cape Air is looking to find a permanent place to dock in the neighborhood but would store its planes overnight at an airport, such as Logan or the airport in New Bedford.

Tailwind tested its service Wednesday, which included one landing and takeoff on the water, chief executive Alan Ram said. Unlike Cape Air, Tailwind’s plane didn’t dock.

The company also tested a number of approaches in which it didn’t land in the water. It’s possible those movements fueled rumors that Tailwind was unable to land the plane in the harbor.

Ram denied that, saying the test went according to plan. He said the two Tailwind pilots reported that it’s easier to land in Boston Harbor than in the East River for a number of reasons. They can be guided by the air-traffic control tower at Logan, the body of water is wider in Boston, and many buildings are lower to the ground.

“From our standpoint, it went fantastically well,’’ Ram said. “We actually think this will be an easier operation in every way than our current operation in New York.’’

Tailwind, which uses the same kind of Cessna as Cape Air would operate, is also seeking a dock along the waterfront. Unlike Cape Air, Tailwind is talking with property owners about locations in which it could take its seaplane out of the water for overnight storage and maintenance.

Ram said both companies would have minimal effect on boating traffic in the harbor, even when they’re each running several flights a day. And the noise, he said, wouldn’t be noticeable for residents who already deal with Logan’s airline traffic.

“We are quieter by an order of magnitude than the jets,’’ Ram said. “We are oftentimes quieter than some of the boats that operate in and around there.’’

Executives said they’re looking forward to meeting with local elected officials and addressing their issues.

“We understand that air service has to fit with what the community wants,’’ Bonney said.

Forry, the Dorchester senator who represents that part of the waterfront, said the two businesses ideally should have held meetings with local elected officials before the flights took place to discuss potential concerns. (Cape Air chief executive Dan Wolf also serves in the Senate with Forry.)

She said she hopes to meet with the companies soon and is keeping an open mind, although she wonders if the busy harbor can accommodate another mode of transportation. “We want to make sure there’s not an additional impact on the community and on the residents,’’ she said.

Jon Chesto can be reached at jon.chesto@globe.com. Follow him on Twitter @jonchesto.