The invention provides a light guide element comprising a light guide and a layer element, wherein the light guide comprises a light guide face and wherein the layer element comprises an optical layer, wherein said optical layer is in contact with at least part of the light guide face, wherein the optical layer has a first index of refraction (n1) smaller than the refractive index of seawater, wherein the light guide comprises a UV radiation transmissive light guide material.

An apparatus for cleaning nets underwater comprising a cleaning head formed from at least one propeller having a perimeter rim available for receipt of knuckles. The cleaning head is positioned against the surface of an underwater net wherein the cleaning features are constructed and arranged to remove growth from the nets.

An apparatus for cleaning nets underwater comprising a cleaning head formed from at least one propeller having a perimeter rim available for receipt of knuckles. The cleaning head is positioned against the surface of an underwater net wherein the cleaning features are constructed and arranged to remove growth from the nets.

The application describes a device in the form of a robot for performing operations on ship hulls. The robot comprises magnetic wheels enabling the robot to adhere to ferrous hulls via magnetic forces and a suspension arrangement for supporting the wheels on a body of the robot and for allowing the robot to travel over uneven surfaces. The wheels include a first pair of wheels and a second pair of wheels, with the pairs of wheels spaced apart from one another along a length of the robot. The suspension arrangement comprises a suspension pivot mechanism allowing a line extending between the centers of the first pair of wheels to rotate relative to a line extending between the centers of the second pair of wheels, along with a camber pivot mechanism for each wheel, with the camber pivot mechanism allowing the axis of rotation of the wheel to rotate relative to the axes of rotation of the other wheels in order that the wheel can align its axis of rotation with the surface of the hull. The magnetic forces for attaching the wheel to the hull act to rotate the suspension pivot mechanism and camber pivot mechanisms. The robot can therefore maintain a secure contact with the hull as it travels over the hull.

An ultrasonic system for treating a submerged surface of a target structure, the system including: an ultrasonic generator for generating electrical energy to drive first and second ultrasonic transducers, the electrical energy including at least two different frequencies including a first and second operation frequency; first ultrasonic transducers configured to be mounted as a first array to the target structure, and connectable to the ultrasonic generator and operable to generate a first ultrasound signal from the first operation frequency; and second ultrasonic transducers configured to be mounted as a second array to the target structure, and connectable to the ultrasonic generator and operable to generate a second ultrasound signal from the second operation frequency, wherein the first and second ultrasonic transducers are spaceable from one another to produce guided ultrasonic waveforms through the target structure including heterodyned frequencies from the first ultrasound signal and the second ultrasound signal.

The invention provides a light guide element (1300) comprising a light guide (300), wherein the light guide (300) in comprises a first light guide face (301) and a second light guide face (302) with UV radiation transmissive light guide material (305) between the first light guide face (301) and the second light guide face (302), wherein the light guide element (1300) further comprises one or more of: (i) a first layer element (30) in contact with the first light guide face (301), wherein the first layer element (30) is transmissive for UV radiation; and (ii) a second layer element (130) in contact with the second light guide face (301), wherein the second layer element (130) has one or more functionalities selected from the group consisting of (a) reflective for UV radiation, (b) adhesive for adhering the light guide (300) to an object, (c) reinforcing the light guide element (1300), and (d) protective for the light guide (300).

The invention provides a light guide element (1300) comprising a light guide (300), wherein the light guide (300) in comprises a first light guide face (301) and a second light guide face (302) with UV radiation transmissive light guide material (305) between the first light guide face (301) and the second light guide face (302), wherein the light guide element (1300) further comprises one or more of: (i) a first layer element (30) in contact with the first light guide face (301), wherein the first layer element (30) is transmissive for UV radiation; and (ii) a second layer element (130) in contact with the second light guide face (301), wherein the second layer element (130) has one or more functionalities selected from the group consisting of (a) reflective for UV radiation, (b) adhesive for adhering the light guide (300) to an object, (c) reinforcing the light guide element (1300), and (d) protective for the light guide (300).

The method and system uses ultrasound (US) transducers in contact with an inboard surface underwater portions of marine vessels or structures. By first digitally generating disruptive, multi-frequency, interfering US waveform signals (complex waveforms, typically replicating a Bessel function) and then converting the signals into analog, the transducers generate disruptive, multi-frequency, interfering US waveforms through the underwater portions of the marine vessels and structures which waveforms disrupt unwanted marine growth on the water-side of the vessel or structure. The digital signals, and also the analog signals, are complex waveform signals, typically produced with a Bessel function. The US transducers are either circular membrane transducers or surface transducers. A computer processor coupled to a memory, generates the complex waveform signals fed to the US transducers.

The method and system uses ultrasound (US) transducers in contact with an inboard surface underwater portions of marine vessels or structures. By first digitally generating disruptive, multi-frequency, interfering US waveform signals (complex waveforms, typically replicating a Bessel function) and then converting the signals into analog, the transducers generate disruptive, multi-frequency, interfering US waveforms through the underwater portions of the marine vessels and structures which waveforms disrupt unwanted marine growth on the water-side of the vessel or structure. The digital signals, and also the analog signals, are complex waveform signals, typically produced with a Bessel function. The US transducers are either circular membrane transducers or surface transducers. A computer processor coupled to a memory, generates the complex waveform signals fed to the US transducers.

A rotary cleaning apparatus for underwater cleaning including a housing, a battery, a motor and a flexible hub system. The flexible hub system includes a toroidal brush system coupled to a circular centrifugal pump assembly. The flexible hub system includes a flexible hub allowing the flexible hub system to bend out of plane. When the flexible hub system is rotated underwater at a curved surface, the brush system cleans the surface while the suction of the centrifugal pump assembly flexes the flexible hub system to evenly contact the surface.