MAJULI: Sitting on her haunches, Ritumani Baruah watches the boat drop anchor and waits for its crew to set up a clinic on the shore.

Twenty minutes later, she asks to see the dentist and is guided to the lower deck of the S. B. Nahor, a boat offering healthcare services that operates on the Brahmaputra river in the northeast Indian state of Assam.

She negotiates the gangplank, slowly climbs down the narrow steps of the boat, ducks her head and enters the makeshift clinic of dentist Bivash Saikia.

Greeted cheerily, she is guided to the portable dentist chair crammed into a tiny space next to a gleaming, grey rectangular box. It is an air compressor Saikia cannot work without, powered by the new solar panels on the boat's roof.

Saikia said conditions in his clinic are "not ideal". "But the very fact that I get enough power to do dental checks means islanders don't have to put off niggling toothache or plan a trip to the mainland to just get a filling done," he explained.

The first of 15 Indian boat clinics to go solar, the S. B. Nahor has for the first time brought a dentist to the doorstep of tens of thousands of people who live on flood-prone river islands in Assam.

And by going solar, it has given remote healthcare a much-needed green shot in the arm, boat doctors say.

ELECTRICAL EMERGENCY

In India, about 55 percent of households depend on the public health system to meet their healthcare needs.

But as of 2015 nearly 35 million people in rural areas relied on local health centres without an electricity supply, according to government data. One in every two primary health centres has no electricity or suffers from power outages.

A 2016 report by the Council on Energy, Environment and Water, a non-profit research agency, said only a fifth of primary health centres meet Indian public health standards, which include having functional infrastructure for electricity.

For the residents of Majuli, the world's biggest river island, and other smaller islands dotting the river, access to healthcare has been an even bigger challenge.

Health centres without doctors, infrequent ferries to the mainland and the remoteness of some islands have meant premature deaths, prolonged illness and challenges in meeting vaccination targets, doctors say.

"In many places we visit, villagers have to travel for two days to get any form of medical help or medicines," said on-call doctor Nayanjyoti Deka. "Even a paracetamol tablet we give means a lot in these areas."

Today, teams of doctors and nurses use the boats to reach 300,000 people in 373 river-island villages across 13 districts in Assam.

Funded by the government's national health mission and run by the non-profit Centre for North East Studies and Policy Research (C-NES), the boat clinics struggled to stay afloat without a reliable power source.

Previously run on diesel generators, they had to use power sparingly and could not operate in the evenings.

"A lot of medical devices are designed on the premise that there will be a constant power supply at hospitals and clinics where they are being used," said Vivek Shastry of Indian sustainable energy charity SELCO Foundation, a partner in the project that installed the solar panels on the S. B. Nahor.

"Baby warmers, dental chairs, X-ray machines - all use a lot of energy. With solar, the power deficit can be compensated."

Off-grid solar systems like that on the boat are a growing source of power in India, particularly in rural areas, but they still provide less than a tenth of the electricity generated by grid-connected solar plants, experts say.

VACCINATIONS AND BLOOD TESTS

After being fitted in May, the S. B. Nahor's 5-kilowatt solar system has enabled much more than dental equipment to run.

Since replacing its noisy, polluting diesel generator as the main source of power, the boat has installed a refrigerator to store vaccines, speeded up laboratory tests and started making announcements via loudspeaker. Most importantly, it is now lit up at night.

"Earlier, we carried vaccines in an ice pack, constantly worrying about the changes in temperature," said Juli Phukan, a nurse on board the boat. "A lot of stock would spoil and even though we were anchored on the islands for days, treating emergency cases that came up at night was a challenge."

In the tiny laboratory on the upper deck, technician Achzot Jyoti Das is busy taking blood samples.

The queue is growing, but he assures patients the wait for their test results will be minimal. "The panels on the roof mean no power outage, and I can run the laboratory centrifuge easily," said Das, as he analysed samples and wrote reports.

"We visit islands once every few weeks by turn, which is why it is important to have these results out. Patients can't wait, can they?"

WHAT DOES A DOCTOR LOOK LIKE?

On a clear October morning, the S. B. Nahor bobs gently on the calm waters of the Brahmaputra river.

Suren Hazarika, 65, a boatmaker from Besamora village, queues up to get his blood pressure checked.

Waiting with him are teenage boys worried about acne, pregnant women at risk of anaemia and elderly patients needing blood-pressure medication.

The doctors, nurses and pharmacist tend to 101 people in the three hours the boat is anchored at Besamora.

Some patients are regulars and exchange warm smiles with boat clinic staff under the blue tent on the bank.

"Many of our patients had never seen a doctor till the boat clinic anchored near their village nearly a decade ago," Ashok Rao of C-NES told the Thomson Reuters Foundation.

"Some name their child after our doctors and some come just to see what a doctor looks like. It is always overwhelming."

When the sun sets over the Brahmaputra, the lights in the boat clinic are switched on.

"It reminds people that we are here and that help is at hand, even if there is an emergency late into the night," said Deka, as the medics gather around an old television set to watch the news.