GB2356129A

GB2356129A - Cleaning device for submerged surfaces

Info

Publication number: GB2356129A
Application number: GB0016577A
Authority: GB
Inventors: William James Godkin
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-11-12
Filing date: 2000-07-07
Publication date: 2001-05-16
Also published as: GB9926690D0; GB0016577D0

Abstract

A device for cleaning a surface which is at least partially submerged in water, where there is relative motion 6 between the water and the surface to be cleaned, the device having a rough surface 2 for effecting the cleaning, a hydrodynamic device 15 for urging the rough surface 2 against the surface to be cleaned as a result of said relative motion 6, at least one shaped surface extending from the front to the rear of the device for providing drag on the device caused by the relative motion and tow line attachment means 8,13 disposed out of line with a t least one of said shaped surfaces so that in it adopts an acute angle relative to the direction of the relative motion and urges the device to dive. Tow cable 5 is used to pull the device in a direction parallel to that of the relative motion, whilst lift cable (4) is used to limit the depth to which the device will dive and to lift it clear of the water.

Description

2356129 CLEANING DEVICES This invention relates to cleaning devices, for

example for the hulls of boats and ships and other structures which are immersed in water.

A wide variety of deposits can form on submerged and partially submerged surfaces for example of the hulls of ships, depending on the nature of the surfaces and the environment in which they are submerged. For example, the hulls of pleasure boats and commercial vessels floating on sea water readily become fouled with various organisms which adhere to their submerged surfaces. This fouling effectively roughens the surfaces on which it forms, with the result that the hydrodynamic drag on the fouled surface is increased. This is-undesirable because it tends to reduce the speed of the vessel through the water, and such deposits are therefore undesirable and need to be removed to improve efficiency.

Undesirable effects caused by increased drag resulting from fouling is not confined to sailing boats and engine powered vessels which move through the water, but it also affects anchored floating bodies, including pontoons and buoys, in addition to anchored ships. Tidal flows past such anchored bodies tend to drag them with the flow, and fouling tends to increase the drag on these bodies, thereby causing increased strain and indeed wear and tear on their anchorages.

Various proposals have been made hitherto for cleaning the surfaces of bodies which are submerged in water. One such proposal is to use chemical surface treatments which are intended to kill and/or discourage the adhesion of marine organisms which attempt to adhere themselves to such surfaces. However, these treatments are environmentally undesirable and furthermore they tend to be effective for relatively short periods of time after their application.

Other means of removing fouling tend to be mechanical, for example involving the use of high pressure water jets, sometimes combined with surface abrasion, for example using brushes. Such methods are costly because they require removal of the fouled surface from the water, this often requiring heavy lifting equipment or a dry dock. Furthermore, removing floating bodies from the water means that they can no longer perform their intended function whilst they are out of the water and being cleaned.

As a result, proposals have been made hitherto for cleaning the outer surfaces of bodies which are normally submerged in water which do not require their removal from the water.

One such proposal is described in DE34348 89-A in which a wedge shaped scraper is connected by its tip to a control cable from the bow of a ship. The drag force on the scraper caused by the flow of water past the ship pulls the scraper under the hull of the ship. The direction of travel of the scraper under the ship is controlled by central control flaps which cause the scraper to oscillate up and down relative to the surface, its position also being controlled by lateral support cables.

A modification of the above scraper is described in DE3834121-A, the direction of travel of the modified scraper under the hull of the ship again being controlled by a single adjustable central control flap or rudder.

According to the present invention there is provided a device for cleaning a surface which is at least partially submerged in water where there is relative motion between the water and the surface to be cleaned, the device comprising a rough surface for effecting the cleaning, means for urging the rough surface against the surface to be cleaned as a result of said relative motion between the water and the surface to be cleaned, a shaped surface extending from the front to the rear of the device for providing drag on the device caused by the relative motion between the water and the surface to be cleaned, and tow line attachment means disposed out of line with the said shaped surface so that in use the shaped surface adopts an acute angle to the direction of said relative motion between the water and the surface to be cleaned and the device is urged to dive.

The means for urging the rough surface against the surface to be cleaned preferably consists of at least one cross member, for example in the form of a hydrofoil, which extends substantially perpendicularly to the said shaped surface.

Devices according to the present invention preferably have at least two shaped surfaces extending from the front to the rear of the device for providing drag on the device, and the means for urging the rough surface against the surface to be cleaned preferably extends between the two shaped surfaces.

Devices according to the present invention are preferably substantially symmetrical about a center line thereof.

The rough surface can be a sheet of an abrasive material or brushes, and the devices can have two or more of rough surfaces.

The tow line attachment means is can be disposed in a front portion of the device. However, it can also be disposed in a rear portion of the device, but in this case it will in general also be guided by a forward portion of the device in order to cause the acute angle to be achieved for diving. In particularly preferred embodiments of the present invention the devices have two tow line attachment points disposed in rear portions of the device on either side of a center line of the device, and the shaped portions disposed on either side of said center line include guide means for the tow line.

Cleaning devices in accordance with the present invention preferably include a lift line for lifting them out of the water, or in particularly preferred embodiments enable the devices to be steered up and down by changing the amount of pull on the lift line.

Embodiments of cleaning device in accordance with the present invention will now be described by way of example with reference to the accompanying drawings in Which:- Fig. 1 is a perspective view of a first embodiment; Fig. 2 is a side elevation of the embodiment of Fig. 1; Fig. 3 is a perspective view of the embodiment of Figs. 1 and 2 with tow and lift lines attached; Fig. 4 is a plan view of the embodiment of Figs. 1 and 2 with different tow and lift lines from those of Fig. 3; Fig. 5 is a perspective view of a modification of the embodiment of Fig. 1; Fig. 6 is a perspective view of a second embodiment; Fig. 7 is a side elevation of the embodiment of Fig. 6; Fig. 8 is a plan view of the embodiment of Figs. 6 and 7; Fig. 9 is a perspective view of a third embodiment; Fig. 10 is a front view of the embodiment of Fig. 9; and Fig. 11 is a perspective view of the embodiment of Figs. 9 and 10 with tow line attached.

The embodiments of cleaning device shown in Figs. 1 to 5 each have a base 1 to which is attached a rough material 2 for removing fouling from a surface to be cleaned. Two side walls 23 and 24 extend vertically upwardly from either side of a front portion of the base 1, each of the walls 23 and 24 having rearward extensions in the form of shaped structures 3, a cross member 15 extending between the two shaped structures 3.

A tow line 5 passes through a hole 8 in the wall 23 and a lift line 4 passes through a hole 9 in the wall 23, knots or some other form of enlargement at the ends of the lines 4 and 5 prevent their being pulled out of the holes 8 and 9. Alternatively, the tow line 5 and the lift line 4 can be passed through holes 13 and 12 respectively, as will subsequently be described in more detail.

Fig. 2 shows the cleaning device immersed in water which is flowing in the direction of arrow 6 over a surface 14 which is to be cleaned, the device being restrained by the tow line 5 extending through the hole 8.

The cross member 15 has a cross sectional shape, for example in the form of a hydrofoil, which causes the water flowing over it in the direction of arrow 6 to move the device towards the surface 14 in the direction of arrow 17. The result is that the rough surface 2 of the device is pressed against the fouled surface 14.

6 - Fig. 3 shows the device on the hull of a sailing boat which is to be cleaned. Because the tow line 5 is attached to one side of the cleaning device, hydrodynamic drag forces on the device caused by water flowing in the direction of arrow 6, and in particular on the shaped structures 3, apply a torque to the device which causes it to rotate about the point of attachment 8 of the tow line 5 to the wall 23, thereby changing the direction of movement of the device. At equilibrium, the device points downwardly at an acute angle to the flow 6 causing the device to move downwardly in the water in the direction of arrow 11.

The pressure in the direction of arrow 17 between the rough under surface 2 of the device and the surface 14, plus movement of the device in the direction of arrow 11, causes the rough surface 2 to move across the surface 14 abrading and therefore cleaning the surface 14.

The lift line 4 is connected to a position which is stationary relative to the surface 14 so that when the line 4 is pulled upwardly, substantially perpendicularly to the water flow indicated by arrow 6, the device is raised, further abrading and cleaning the surface 14. Releasing the line 4 allows the device to move back downwardly in the water flow in the direction of arrow 11.

By adjusting the length of the line 5, the device can be moved to different areas of the body to be cleaned, for example those extending on either side of the surface which has already been cleaned.

The arrangement of tow line 5 and lift line 4 shown in Fig. 4 avoids the need to remove and reconnect these lines when the device is used with water flowing in the opposite direction to that shown in Fig. 3. Thus the tow line 5, which is prevented from being pulled out of the hole 13 by a knot 21 can simply be pulled from one end to the other through the holes 8 and 13 until a knot 19 at the other end of the line 5 prevents it from travelling any further. In a similar manner, the lift line 4 can be pulled through the holes 9 and 12 until a knot 20 prevents it from being pulled through the hole 12.

The embodiment shown in Fig. 5 is essentially identical to that of Figs 1 to 4 except that it includes a further cross member 16 which is an additional to cross member 15. The cross member 16 serves to increase or modify the pressure distribution between the surfaces 2 and 14, the pressure on the surface 14 depending on a number of factors including the shape and location of the cross members 15 and 16, the viscosity of the water in which the device is used, and the speed of flow of the water relative to the surface 14.

The embodiment shown in Figs. 6 to 8 is similar to that of Fig. 5 in that it has a base 1 to which is attached a rough material 2 for removing fouling from a surface to be cleaned. Two side walls 23 and 24 extend vertically upwardly from either side of a front portion of the base 1, each of the walls 23 and 24 having rearward extensions in the form of shaped structures 3, two cross members 15 and 16 extending between the two shaped structures 3.

Unlike the embodiment of Figs 1 to 4, and the variant in Fig. 5, the embodiment of Figs. 6 to 8 the tow line 5 is connected to a ring 26 to which are connected two control lines 25 and 251. Each of the control lines 25 and 25' passes through a respective bore 27, 271 in the front end of the walls 23 and 24, the holes 27 and 271 extending rearwardly through the walls 23 and 24 into a through aperture 28 in the cross member 16, and then through the aperture 28. The lines 25 and 251 therefore cross within the aperture 28.

The control line 25' is secured to a fastening point 291 at the rear of the base 1, and although there is a symmetrically disposed fastening point 29 on the opposite side of the base 1, the control line 25 is connected to a lift line 4 by a ring 301.

Relative movement between the surface to be cleaned by the device and the water in which it is submerged causes the cross members 15 and 16 to press the device against the surface to be cleaned, and since the control line 25' is secured to the fastening point 29' whereas the control line 25 is not secured to the fastening point 29, the device rotates in a similar manner to that shown in Figs. 1 to 4. Cleaning of the surface 14 therefore takes place in a similar manner. When desired, the device can be raised by pulling on the control line 4.

The device shown in Figs. 6 to 8 can be made to dive in the opposite direction to that which occurs with the control lines arranged as in Figs 6 simply by disconnecting the lift line 4 from the control line 25, connecting the control line 25 to the fastening point 29, disconnecting the control line 25' from the fastening point 29', and then connecting the lift line 4 to the ring 30'.

It should also be noted that careful pulling of the control line 4 can be used to cause the device to move upwardly relative to the surface being cleaned but without loss of contact between the device and the surface as might occur if the line 4 is pulled strongly. Fig. 8 illustrates how the device can be made to travel substantially horizontally over the surface to be cleaned by careful pulling of the lift line 4. The control lines 25 and 251 shown as continuous lines in this drawing show the device oriented for diving, and as broken lines they show the device travelling substantially horizontally. Further pulling on the control line 4 will cause the ring 30 to move to a position below the mid-line of the device, the device then being caused to rotate so that it rises in the water.

A third embodiment of device in accordance with the present invention is shown in Figs. 9 to 11 which mainly differs from the previous two embodiments in not having a base 1.

The device shown in Figs. 9 to 11 consists of two side walls 40, 41 connected together by two cross members 15 and 16. Apertures 42 in the side walls 40, 41 effectively define two shaped structures 43 which connect to respective runners 44, 441, cleaning brushes 45, 451 being attached to the runners 44 and 44'.

Bores 46, 461 extend from the front and through the thickness of the two walls 40, 41 into an aperture 47 through the thickness of the cross member 16.

Securing points 48, 481 are provided at the rear end of the runners 44 and 441 respectively, and they are used to secure control lines 25 and 251.

Fig. 11 shows the control lines 25 and 25' threaded through the bores 48 and 48', and then through the aperture 47 through the thickness of the cross member 16 in a similar manner to the control lines 25 and 251 shown in Fig. 8. One of the control lines 25 and 25' is then secured to its associated securing point 48 or 48', a ring 49 being connected to the control lines 25 and 251 and also to a tow line 5. The other of the control lines 25 and 251 is connected to a lift line 4.

The cleaning device shown in Figs 9 to 11 functions in a similar manner to that shown in Figs. 6 to 8, the hydrofoil section cross members 15 and 16 causing the device to be pressed against the surface to be cleaned as a result of relative movement of the device and the water in which it is placed. Rotation of the device about the point where the control line 251 enters the aperture 46' caused by drag of the water over the device then causes the device to dive.

Yulling the lift line 4 connected to the free end of the control line 25 causes the device to return to the surface of the water, and indeed it can be used to steer the device over the surface to be cleaned in a similar manner to that described with reference to the embodiment shown in Fig. 6.

The device can be made to dive in the opposite direction to that obtained with the control lines connected as in Fig. 11 by disconnecting the control line 25' from the securing point 48, and then connecting the line 25 to the securing point 481 and the control line 25' to the lift line 4.

Devices can be made of a variety of materials, for example plastics and/or metal. Plastics are generally preferred as they minimise the risk of damage to surfaces over which they pass. In addition, plastics are generally less dense than water, and as a result devices made from them will tend to float in the event that they become disconnected from the tow and/or lift lines. However, excessive buoyancy is generally undesirable, and parts of the devices which define voids, for example the cross members 15 and 16, preferably have holes into which water can enter when the devices are in the water.

Claims

1. A device for cleaning a surface which is at least partially submerged in water where there is relative motion between the water and the surface to be cleaned, the device comprising a rough surface for effecting the cleaning, means for urging the rough surface against the surface to be cleaned as a result of said relative motion between the water and the surface to be cleaned, a shaped surface extending from the front to the rear of the device for providing drag on the device caused by the relative motion between the water and the surface to be cleaned, and tow line attachment means disposed out of line with the said shaped surface so that in use the shaped surface adopts an acute angle to the direction of said relative motion between the water and the surface to be cleaned and the device is urged to dive.

2. A device according to claim 1, wherein the means for urging the rough surface against the surface to be cleaned comprises at least one cross member which extends substantially perpendicularly to the said shaped surface.

3. A device according to either of the preceding claims, wherein the means for urging the rough surface against the surface to be cleaned comprises at least one cross member in the form of a hydrofoil.

4. A device according to any of the preceding claims, having at least two shaped surfaces extending from the front to the rear of the device for providing drag on the device.

5. A device according to claim 4, wherein the means for urging the rough surface against the surface to be cleaned extends between the two shaped surfaces.

6. A device according to any of the preceding claims, wherein the device is substantially symmetrical about a center line thereof.

7. A device according to any of the preceding claims, wherein the rough surface comprises a sheet of an abrasive material.

8. A device according to any of the preceding claims, having two or more of said rough surfaces.

9. A device according to any of the preceding claims, wherein the tow line attachment means is disposed in a front portion of the device.

10. A device according to any of claims 1 to 8, wherein the tow line attachment means is disposed in a rear portion of the device.

11. A device according to claim 10, including means whereby a tow line can be attached to a rear portion of the device whilst also being guided by a forward portion of the device.

12. A device according to claim 11, including two tow line attachment devices disposed in rear portions of the device on either side of a center line of the device, and guide means associated with shaped portions disposed on either side of said center line.

13. A device according to any of the preceding claims, including means for attaching a lift line thereto.

14. A device for cleaning a surface which is at least partially submerged in water where there is relative motion between the water and the surface to be cleaned, the device being substantially as herein described with reference to the accompanying drawings.