Pleasure boating in the Mediterranean: a leisure activity under ecological pressure

The UN Ocean Summit concludes tomorrow with the "Nice Ocean Declaration" and the "Nice Ocean Action Plan," which, according to NGOs and scientists, will not meet the challenge. While the Mediterranean has, for example, begun its transition to less polluting maritime transport, a blind spot remains: pleasure boats, whose obsolescence and ecological impact remain overlooked. Yet in Marseille, for the past 5 years, local actors have been experimenting with sustainable and low-cost solutions that could help preserve biodiversity.

By Olivier Martocq

The column "A Fragile World" will be dedicated from May 29 to June 19 to the 3rd United Nations Ocean Conference (UNOC3). It will be freely available in the 22 countries around the Mediterranean and in 11 languages thanks to our partner, the Région Sud.

Since May 1, 2025, the Mediterranean has officially become a SECA (Sulfur Emission Control Area), prohibiting toxic emissions from merchant ships. This is a major advance for air quality around the Mediterranean. However, another source of pollution still escapes detection: recreational boating. In French waters, more than 420,000 leisure boats, often old, still run on diesel or gasoline, and their environmental impact is largely underestimated. 90% of this fleet measures less than 12 meters, and 80% are sailboats or motorboats equipped with propulsion systems designed more than two decades ago. As a result, these vessels pollute between 3 and 37 times more than the most recent cars, according to tests conducted at the Old Port of Marseille by the AtmoSud observatory. Dominique Robin, its director, explains the phenomenon. "Pleasure boat engines are often unfiltered, unlike cars. The combustion is raw."

Boats pollute between 3 and 37 times more than the most recent cars © DR

A large-scale experiment at the Old Port of Marseille

On June 6, a presentation of five years of research took place in the bay of the reserve, labeled "clean port." Among the boats used for this campaign, an old Bertram from the 1980s stood out as a case study. This vessel, made available by Alexandre Michel Flandin, an experienced sailor, was equipped to measure pollution in real conditions. During the first tests conducted in 2022, it literally blew up the sensors: its emissions were equivalent to those of 37 cars. Since then, this same boat has served as a testing platform to adapt an electric kit to the latest generation diesel engines. "It wasn't an easy task," acknowledges the owner. "We had to find solutions to hybridize engines fully managed by electronics, adapt the hull." The total cost of this prototype, which includes a new engine, an electric kit, trials of eco-friendly underwater paints, a GPS anchor, dry toilets, and a refrigerator powered by photovoltaic sensors, amounts to less than €400,000. Of which 30% is funded by the Région Sud. This budget remains well below that of a new boat of the same category.

In terms of environmental impact, the refit generates much less CO₂ than new construction. It has also allowed local shipyards and craftsmen to work, with materials representing about half of the total cost.

Accessible solutions for less than €5,000

But while the research has been costly, the results are promising. Jean-Pascal Plumier, founder of OZO, a company specializing in electric motors for bicycles, has adapted his kits for boating. "With a hybrid system, we use a small electric motor for maneuvers in the harbor, and the thermal engine takes over at sea, recharging the battery. This keeps us below the €5,000 mark.", he explains.

These kits are designed to be adaptable to most small boats. Meanwhile, new accessories like GPS anchors, which prevent disturbing the seabed, are presented to boaters as simple and effective tools for preserving biodiversity.

A shared awareness

For Antoine Cabassus, director of the Reserve port managed by the Marseille Provence Chamber of Commerce and Industry, this experiment marks a turning point. "Our port has become a laboratory for sustainable boating. We are already welcoming hydrogen and electric boats. We want to show that another path is possible," he emphasizes. The same sentiment is echoed by Michel Lamberti, president of the Federation of Nautical Societies of Bouches-du-Rhône: "Either we roll out the carpet and forget what we've seen, or we take action. We must support this transition, especially in the coastal strip of 300 meters, where ecological pressure is the highest."

The 300-meter strip: a crucial issue

It is precisely in this zone, where 80% of marine biodiversity is concentrated, that the majority of recreational activities take place. Cyprien Fontvieille, general director of Neede, insists: "Our study launched in 2020 revealed the extent of the impact of small vessels on this coastal strip. We have therefore designed an ecology of solutions, co-constructed with boating federations. A citizen convention to draft future regulations, and a roadmap aimed at establishing decarbonized navigation by 2032 would be a particularly effective and welcome tool."

An economic and political challenge

The Région Sud, one of the most touristic areas of the Mediterranean coast, finds itself at the heart of the debate. "With more than 147 ports and 60,000 mooring rings, boating represents more than one billion euros in our economy," recalls Christophe Madrolle, president of the Sea and Coast Commission. "We must reconcile economic attractiveness and environmental protection." However, the issue of recreational boating remains delicate: reforming without breaking a pillar of coastal tourism, engaging without punishing users.

Towards a more responsible Mediterranean boating

While the UNOC brought world leaders together in Nice to think about the future of the oceans, Marseille took concrete actions. The paradox is striking: in the same sea, cargo ships must reduce their emissions, while recreational boats, sometimes more polluting on a unit basis, escape all regulation. Through its tests, prototypes, and social experiments, the city of Marseille demonstrates that the transition is not only possible but already underway. It remains to be seen whether the relevant institutions will take it up.