Ships – Implements – Hull cleaning
Reexamination Certificate
1999-11-16
2001-04-03
Swinehart, Ed (Department: 3617)
Ships
Implements
Hull cleaning
Reexamination Certificate
active
06209473
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of, and apparatus for, removing marine fouling from an underwater surface, e.g. a ship or boat hull, coated with an antifouling material of the type providing a surface of low adhesion for the marine fouling. Preferably, but not exclusively, the antifouling material is a non-biocidal antifouling material.
The outer surface of a boat hull needs to resist fouling caused by adhesion thereon of marine organisms such as barnacles and algae. Conventionally fouling has been inhibited by coating the boat hull with an antifouling paint containing a biocide for marine organisms which gradually leaches from the paint. Nowadays the continual leaching of toxic substances from a boat hull is considered to be an unacceptable contamination of the surrounding water.
More recently, antifouling paints have been developed based on hydrolysable copolymers, such as triorganotin polymers. With these paints, the layer of paint is gradually dissolved from the surface of the hull as the boat moves through the water. However, the effectiveness of this product is reduced since the period over which the paint is effective is limited. Moreover, poisonous substances are again leaked into the surrounding water.
Presently non-biocidal antifouling materials have been developed for application to the hulls of boats to prevent or resist the adhesion thereto of marine fouling organisms. Such non-biocidal antifouling materials conveniently comprise a silicone rubber, especially a room-temperature-vulcanised silicone rubber, on the surface of the hull. These antifouling materials provide a relatively smooth and slippery or “non-stick” surface for marine foulings, such as weeds and barnacles, and are referred to as low surface energy antifouling paints. During motion of the boat through the water, any such marine foulings which are attached to the coated boat hull become removed as a result of the movement of the boat through the water. The main advantage of such antifouling materials is that they do not leach poisonous materials, e.g. biocides, into the water. However, the antifouling material provides a relatively soft and delicate coating which, because it contains no biocides, is less effective at deterring the attachment of marine organisms thereto than biocidal antifouling materials. Therefore a hull coated with such an antifouling material requires subsequent cleaning to prevent the build up of marine foulings. A problem with cleaning such a coated hull is that, if scrubbed with brushes, the relatively soft and delicate antifouling material tends to become removed from the boat hull.
SUMMARY OF THE INVENTION
The present invention seeks to provide an apparatus and method for effectively cleaning hulls of boats or other underwater structures coated with antifouling paint of the type providing a surface of relatively low adhesion for the marine fouling.
According to one aspect of the present invention there is provided a method of removing marine fouling from an underwater surface coated with an antifouling paint of the type providing low adherence for marine fouling or growth, the method comprising generating, with at least one treating member spaced from the underwater surface to be cleaned, turbulence within the water surrounding the underwater surface to be cleaned so as to dislodge marine fouling adhering to the surface to be cleaned.
The turbulence within the water created by the at least one treating member has a similar effect as if the underwater surface, e.g. a boat hull, is moving through the water. Thus the generated water movement dislodges any marine fouling from the underwater surface without the need to contact the underwater surface directly with the treating member(s).
Preferably, the generation of the turbulence within the water is created by rotation of the or each treating member. The or each treating member conveniently comprises a disc having a number of vanes mounted thereon which on rotation of the treating member causes the desired turbulence within the water surrounding the underwater surface to be cleaned. The provision of a rotating treating member has the advantage of creating a suction force towards the underwater surface being cleaned in addition to creating localised high speed water movements. If the treatment member is mounted on a wheeled cleaning vehicle, the vehicle will be sucked against the underwater surface when the treating member is rotated.
According to another aspect of the present invention, there is provided apparatus for cleaning an underwater surface comprising a wheeled chassis maneuverable over the underwater surface to be cleaned and at least one surface treating member mounted on the chassis, characterised in that the or each surface treating member is constructed and arranged so that, in use of the apparatus under water, the or each treating member is spaced from the underwater surface to be cleaned and generates water movements over, so as to detach fouling from, the underwater surface.
Preferably the or each surface treating member is rotatably mounted on the chassis. In this case the apparatus further includes drive means for rotating said surface treating member(s) and, preferably, also control means for moving the or each treating member between inner and outer positions in both of which positions it is spaced, in use, from the underwater surface to be cleaned. Suitably the or each treating member comprises a plurality of vanes mounted on a backing plate.
If the or each treating member is a rotatable treating member, its rotation, in use of the apparatus underwater, also serves to generate a suction force holding the apparatus against the underwater surface to be cleaned.
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patent: 5048445 (1991-09-01), Lever et al.
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Jackson Joseph
Jones David Fitzherbert
Dann Dorfman Herrell and Skillman
Skillman Henry H.
Swinehart Ed
UMC International Plc
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