As a sailor, Pedro Rodrigues has spent years looking for an advantage on the high seas. But during the upcoming Olympics in Rio, he’ll be flying in a helicopter, swooping low over the azure waters of Guanabara Bay looking for floating plastic bags, logs, and submerged furniture that could destroy a boat and wreck an Olympic race.

Rodrigues, a 35-year old race judge with the World Sailing Federation, will be up in the air every morning at 6 am the week before racing begins, carrying a laptop with wind, weather, and current data from Brazil’s oceanographic agencies. “I’m looking for something that can damage or stop the boat,” Rodrigues says. “Like a sofa, or something big.” When he spots something, he’ll radio its GPS positions to a fleet of “eco-barcos”— floating street sweepers built to scoop the trash from the water.

Last year, during a dry run of the Olympic sailing race, Rodrigues spotted coconuts and bits of wood. And a floating fridge. “That was a bit strange,” he says.

Preparations for next month’s Rio Olympics have been cursed in more than one way. Some Olympic athletes have pulled out because of fears of contracting the Zika virus, while researchers continue to find raw sewage and antibiotic-resistant bacteria not far from where long-distance swimmers and triathletes will compete.

And because raw sewage and stormwater from Rio’s favelas dump right into Guanabara Bay, the waterway collects tons of debris from neighborhoods and backyards. The Dutch environmental ministry and a group of NGOs came up with several ideas to clean up the bay, including nets of bubbles in the water, and stringing plastic fencing along tributaries to catch the debris upstream. But their project was abandoned in 2015 because the city of Rio ran out of money, according to Henry Raben, head of compliance for Tauw, a Dutch environmental engineering firm.

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Even with the right funding, it’s not a problem that will go away easily. Water quality and marine life has declined from decades of untreated sewage, petrochemicals, and debris, says marine biologist Fabiano Thompson, who studies the bay's ecosystem at the Federal University of Rio de Janiero. “It’s been almost 30 years and there’s not much progress,” he says. “Of course, the Brazilian government does not want to expose this. But it is a rather simple solution: You just stop dumping sewage.”

During last year’s test event in Rio, sailing officials were forced to move the course out to sea to avoid floating garbage.

Olympic sailors pride themselves as a hardy bunch, but floating furniture, fridges, and TV sets do get them on edge. During last year’s test event in Rio, sailing officials were forced to move the course out to sea to avoid floating garbage. But the winds died, so they moved the sailboats back into the harbor, says Malcolm Page, a two-time Olympic gold medal winner for Australia in the 470-class sailing event, now working for the World Sailing Federation.

The teams avoided any big crashes. “If you saw a floating Pepsi bottle, it doesn’t have much density and it wouldn’t affect a boat,” says Page. But they did get slowed down by plastic bags and seaweed. “They wrap around the foils [the rudder, keel, or centerboard], and that affects the stability,” he says.

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Tangled kelp and plastic are more of a nuisance than a threat, and common in many urban harbors from San Diego to Sydney. But a collision with bigger pieces of junk like the ones the Rodrigues has seen from his chopper can smash sailboats that weigh upward of 600 pounds and travel at 30 to 40 miles per hour downwind. “It hurts when you come to a stop suddenly,” says Page. “I’ve got a few chipped teeth and scars just from nose-diving into a wave.” Others have gotten broken bones and black eyes.

Still, both Page and Rodrigues say that Rio can pull off a junk-free Games, especially if it stays dry. Less rain means less junk-flushing. As a back-up plan, seven race courses will be set up each day, three more than the event schedule calls for. “We’re confident we are going to stick to schedule,” says Page.

This year, he will be watching the Olympic sailing events from the deck of an observer boat. He’s hoping any bruises will come from sailors rubbing elbows—not crashing their rigs into that floating sofa.