Robots Weblog | Boat cleansing: This robotic defies salt water

Italian designers from Aeffe optimize diving robots with lubrication-free and corrosion-resistant polymer bearings from igus

Cologne, July 23, 2026 – It’s every boat owner’s horror: algae, mussels and barnacles that have to be removed from the hull before the start of every season. However, the stowaways should be easier to remove in the future: with a remote-controlled diving robot called KeelCrab from the Italian company Aeffe. But in order for the little crawler to be able to work permanently underwater, the developers had to solve a drive challenge. The storage of the drive rollers with lubrication-free polymer plain bearings from igus plays a key role.

At first glance everything seems very simple: the owner lets the KeelCrab into the water. Using a joystick and camera, he controls the robot over the boat’s hull while two brushes remove deposits. But the construction wasn’t quite that simple. Keyword: locomotion under water and overhead. The designers had to develop a drive that was suitable for underwater use. They decided on a vacuum pump, which the robot uses to attach itself to the hull, and two caterpillar tracks. “The storage of the four drive rollers was a real problem here,” remembers Mattia Pagani, development engineer at Aeffe. “We were looking for a solution that was as fail-safe and low-maintenance as possible for underwater use, while at the same time not increasing the weight of the robot too much.” The developers finally found the solution for mounting the four drive rollers in plain bearings made of the high-performance plastic iglidur X from igus.

Fail-safe bearings for underwater use
Use under water is a challenge for many conventional storage systems. “Classic lubricated rolling bearings were out of the question because of the risk of corrosion,” explains Mattia Pagani. The igus plain bearings made from high-performance polymers, however, are corrosion-free. Another advantage: Unlike many standard plastics, the iglidur X material absorbs very little moisture. The bearings remain dimensionally stable, even in continuous contact with fresh or salt water. “This is an essential prerequisite for the long-term, reliable underwater use of our robot.”

Lightweight and economical
But it wasn’t just the risk of corrosion that played a role in the selection of plain bearings for the robot’s drive. At the same time, the designers placed emphasis on low weight and low operating costs. “We briefly thought about single-row radial bearings made of stainless steel Ionox with seals, but they would have been too heavy and too expensive,” says Mattia Pagani. “Due to their low material density, the polymer bearings from igus weigh around 80 percent less than comparable metal bearings.” At the same time, they work permanently dry thanks to integrated solid lubricants. There is no need for lubricants or the associated maintenance work. Mattia Pagani: “This reduces operating costs over the entire period of use, an advantage from which the operators of the robots ultimately also benefit.”