Robots Below the Waterline: Fraunhofer IGP’s ROV Coating Repair Research

At the 2026 Wind & Maritim conference in Rostock, Fraunhofer IGP presented something we find quietly remarkable: a robot arm driving a Subsea Bristle Blaster® across coated steel underwater, as the preparation stage of a fully ROV-based coating repair process for offshore structures. This article summarizes the research - the full presentation by M.Sc. Julia Schubert (Corrosion Protection Technology, Fraunhofer IGP) is available as a PDF (German).

The problem: small damage, deep water

Corrosion protection of offshore structures stands or falls with an intact coating. Transport, installation and operation cause local damage - and the underwater and splash zones are where damage matters most and access costs most: high corrosion rates, short diver windows, high cost, elevated safety risk. Inspection has already moved to ROVs; repair, so far, has not.

The lab rig

Fraunhofer IGP's test setup pairs a Universal Robots UR10e arm with the Subsea Bristle Blaster® and its high-pressure pump, working on 500 × 500 mm plates coated with a realistic offshore system: two epoxy layers plus PU topcoat, roughly 1,200 µm total. The robot varies what an operator would: tool standoff (48-50 mm), passes (6, 10, 18), travel speed (39 mm/s), track spacing (2.5 mm) - turning technique into measurable process parameters.

The measured results

The bristle tool stripped the coating system and profiled the steel underwater, with roughness Rz verified by stylus measurement. Repair coating applied underwater in two layers (~690 µm) reached pull-off adhesion up to 13.5 ± 1.3 MPa (ISO 4624), varying by position - honest numbers from a process still being tuned, and already in the range serious repair systems ask for.

From lab to sea

A prototype ROV with an application tool exists, and a first field trial - coating application in the Warnow river - has run. The stated goal: one combined ROV process covering de-coating, surface preparation and repair coating on offshore structures, with systematic parameter studies ongoing. This extends the research line that began with the 2016 underwater preparation study and led to the commercial Subsea tool now in offshore service.

Why we're sharing it

Because it is independent research: Fraunhofer chose the tool, ran the measurements and reported position-dependent scatter alongside the headline number. That is how surface preparation claims should be made. It also points at where this field is going - robotic preparation is already real above water with the Prepper® systems and Aeroblaster® drone; below the waterline is next.