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Spectral Imaging Powered Ship Hull Biofouling Detection and Cleaning

Periodic Reporting for period 1 - SleekShip (Spectral Imaging Powered Ship Hull Biofouling Detection and Cleaning)

Reporting period: 2020-04-01 to 2021-07-31

Biofouling on ship hulls is a long time and well-known curse that has a direct impact on vessels drag and fuel consumption, representing more than 600 M€ of extra expenses per year for the maritime industry and consequently very significant additional gas emissions. Besides, uncleaned fouling on long haul vessels fosters the spreading of invasive species, which may be harmful to local marine life. This has resulted in more and more stringent regulations in some countries willing to preserve their marine environment.

Detecting very early stages of Level of Fouling (LoF 0-1, thin slime) is essential as it already increases vessel drag but can be cleaned with a soft method avoiding damaging the hull coating. This approach means that the detection and cleaning system must be very cost effective and user friendly to avoid increasing the maintenance expenses for the ship owners.

The ambition of the SleekShip project is to propose a novel approach to ship hull cleaning by allowing early detection of this biofouling and cost-effective and soft cleaning of the hulls using a single unmanned underwater robotic system specially designed to reach the objectives both in terms of technical performance and production costs.
The SleekShip consortium has 5 partners, two high tech SMEs: Subsea Tech (SST - France) specialized in underwater robotics, QCell (QCL - Greece) focusing on hyperspectral imaging, one Research Centre: TWI Hellas (THL - Greece) working on navigation control and two end users: M.Danchor (MDR - Israel) a diving company dealing with ship hull maintenance and DANAOS (DNOS - Cyprus) a container ships owner.

The SleekShip technical work programme is articulated around four technical developments:
- an underwater hyperspectral camera capable of capturing optical information in different wavelengths moving beyond the visible spectrum and thus detecting very low levels of fouling. Besides, the hyperspectral technology performs much better than standard RGB cameras in turbid waters and this will allow inspection in usually murky harbour environments,
- a cavitation jetting system modified to be integrated on a light underwater robotic system, allowing cleaning operations without damaging hull coatings. Such a system shall also be complemented by a debris suction and filtering device to avoid spreading the fouling in the environment, as required by many national regulations,
- a specially designed underwater robot or ROV (Remotely Operated Vehicle) capable of supporting both the hyperspectral imaging camera and the cleaning tool with a production cost under 30 k€ per unit to compete efficiently with diver operations,
- semi-automatic navigation software with cruise control algorithms to enhance the performance of the system and relieve the ROV operator from tedious piloting tasks. Such software will upgrade the ROV into a SAUV (Supervised Autonomous Underwater Vehicle) using a set of internal and external navigation sensors.
The works performed by the SleekShip partners during the elapsed period (M1 to M16) are the following:
- The system definition as well as its operational and economical constraints have been discussed at length between the developing partners, SST, QCL and THL, and the two end users MDR and DNOS. This initial phase allowed us to come up with the system functional specifications and preliminary operational procedures.
- QCL have developed the underwater hyperspectral camera and a full-scale prototype has been manufactured. It has been tested in lab conditions and in a shallow water pool. Sample plates with various levels of fouling are prepared for the upcoming real tests. A special image processing algorithm has been developed to enhance vision in turbid waters, eliminating the water particles between the camera and the target.
- Based on the existing Tortuga inspection class ROV, SST have designed and manufactured a lighter and cheaper vehicle capable of carrying the hyperspectral camera and the cleaning system while keeping future production costs below 30 k€. Baptised as “Mini Tortuga”, this new vehicle is now operational and has performed real environment trials in Marseilles harbour. Additional tuning is ongoing to enhance the thrusters’ performance.
- THL have developed the smart cruise control algorithm which runs on the onboard computer and allows the ROV to automatically follow the ship hull along horizontal lines using a dedicated positioning system. The pilot interface for real time visualisation and remote control mode have been jointly designed by SST, THL and QCL.
- Dissemination media such as website ( social media accounts, brochures and advertising supports have been created by SST as planned, all based on a proper brand guidelines document. All partners have been involved in dissemination activities and KPIs in terms of website page views and social accounts posts are exceeded.
- SST and QCL have worked in expanding their existing distribution network in order to ensure the promotion of the future products. Marketing actions have already been undertaken to allow the early commercialisation of the SpectralSea camera and the Mini Tortuga ROV as stand-alone products and first customer inquiries have been responded to.
Several results are already believed to be beyond the state of the art such as:
- an underwater hyperspectral camera and its associated software allowing detection and characterisation of ultra low levels of biofouling, beyond the visible spectrum.
- a compact and lightweight ROV (15 kg) capable of supporting a cavitation cleaning rotor in water currents up to 3 knots with its associated debris recovery system.

Other expected results by the end of the project are the smart cruise control software which will enable the ROV to become a SAUV and therefore improve its efficiency and relieve the operator from tedious piloting tasks.

The SleekShip project has several potential impact:
As stand-alone products, these results will have a direct impact on SST and QCL competitiveness in their respective markets. THL will have the possibility to further valorise its smart cruise control software development by approaching other ROV manufacturers.
As a complete system, SleekShip units will contribute to significantly reducing the shipping industry fuel expenses and gas emissions by removing biofouling in its early stage. The early cleaning operation will also lower the risks of spreading invasive marine species and endangering local ones.
Finally, its unmanned architecture will allow conducting complete diverless operations, including in contaminated and murky waters, thus reducing the human risk at sea and improving the workers’ safety.
The SleekShip system