FLOATING BOOM
1 The present invention relates to floating or marine booms such as are used for controlling and containing the spread of oil, debris and other pollutants floating on water. More particularly, the 5 invention relates to fence-type booms in which a skirt or curtain is supported in an upright position in the water by some suitable form of buoyancy and extends partly above and partly below the surface of the water so as to impede the spread of pollution.
10 Fence-type booms have been favoured in the past for their ease of deployment and minimum storage space requirements. These advantages, however, have been offset by the basic instability of such booms in rough water conditions. Due to lack of flexibility in the
15 vertical direction, fence booms suffer from two problems, that is, they tend to "bridge" waves, with a consequent loss of pollutants beneath the boom, and can readily be flipped over, often repeatedly so that they completely fail in containment.
20 It is an object of the present invention to provide a construction of fence-type boom which alleviates the above-mentioned problems and which is also flexible in a generally vertical direction.
The invention consists in a floating boom in
25 which a curtain member is supported in an upright position by buoyancy means characterised in that, in the length direction of the boom, the curtain member has a configuration in plan which affords the boom a concertina characteristic, that is, an ability to flex
30 in at least a vertical plane as well as horizontally. This concertina characteristic may be induced by arranging the curtain member so as to have a sinuous
configuration in plan. For example, it may have a serpentine configuration in plan or have generally vertical pleats, kinks, folds of other gatherings of the curtain fabric disposed at spaced positions along its length. In any event, the invention relies basically on in-built directional changes of the curtain member, when viewed in plan, whilst the overall line of the boom remains uni-directional. These directional changes do not need to be consistently equal nor even regular and can be largely random for the resulting concertina characteristic to provide flexibility. However, in general, the sinuous shape of the curtain member will be regular.
The buoyancy means may comprise a line or row of spaced buoyancy members and the curtain member may be threaded about the buoyancy members in a serpentine configuration so that the curtain member is disposed on opposite sides of alternate buoyancy members. Alternatively, the curtain member may be arranged along one side of the row of the spaced buoyancy members and may be pleated or kinked in the spaces between adjacent buoyancy members. In either of these embodiments, the buoyancy members may be joined together in a row by one or more flexible elements, such as, chains, cables or ropes, and the curtain member may be fastened in some suitable manner to the buoyancy members.
In the embodiment in which the curtain member is threaded in a serpentine manner about a row of buoyancy members, additional rows of spaced buoyancy members may be disposed along opposite sides of this first row with the buoyancy members of the additional rows being arranged in pairs spanning the spaces between adjacent buoyancy members of the first row. In a preferred form of this embodiment, the curtain member is a rubberised
fabric, for.example, conveyor belting, and the buoyancy members are pneumatic tyres arranged in upright positions and, if necessary, provided with suitable means to enhance their buoyancy. For example-, at least within their upper sections, the tyres may be provided with a filling of closed cell plastics foam, for example, formed from expanded polyurethane. The plastics foam material may be expanded in-situ or, alternatively, it may simply be cut from pre- oulded lengths of the foam material, conveniently, of circular cross section. The components of such a boom may be assembled together by means of flexible loops or clamps extending through the central openings in the tyres and through small holes in the curtain member. Such a boom may be cheaply and readily constructed with unskilled labour from heavy duty re-cycled industrial products which are available at minimal cost_in most countires throughout the world. These recycled industrial products are extremely tough and abrasion resistant and can be used to fabricate a boom according to the invention which is strong and has a relatively long operational life so that, in effect, it can be permanently deployed and, moreover, produces a boom which is flexible and stable and can ride adverse combinations of wind, waves, current and tide without instability and undue escape of pollutants contained by the boom.
In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings, in which:-
Figures 1 , 2 and 3 respectively illustrate a plan view, an elevational view and a cross section of a first embodiment of the invention.
Figures 4 and 5 respectively illustrate a plan view and a cross section (taken along the line V-V of
Figure 4) of a second embodiment.
Figures 6 and 7 illustrate views similar to Figures 4 and 5 of a third embodiment, and
Figures 8, 9 and 10 respectively illustrate a plan view, an elevational view and a cross section (taken along the line IX-IX of Figure 8) of a fourth embodiment.
Referring to Figures 1, 2 and 3 of the drawings, this embodiment comprises a curtain member 1 formed from reinforced rubberised fabric, for example, heavy duty rubber and p.v.c reinforced conveyor belting, which is supported in an upright position by buoyancy means in the form of rows of pneumatic tyres 2,3,for example, automobile tyres, of smaller diameter than the width of the curtain member, and arranged in upright positions along the sides of a bottom marginal portion of the curtain member so that the latter projects above the tyres. The curtain member 1 is threaded about a centre row of tyres 2 in a serpentine manner so that it is disposed on opposite sides of alternate tyres 2. Disposed along opposite sides of the centre row of tyres 2 and arranged in pairs spanning the spaces 4 between adjacent tyres 2 of the centre row are additional pairs of tyres 3. The components of the boom are flexibly linked together in assembled relation by loops of chain 5 threaded through the central openings in the tyres. Each chain loop 5 extends through a central* opening in a tyre 2 of the central row and through the central openings of adjacent tyres 3 in the two outside rows to couple adjacent tyres in the outside rows together. The chain also extends through small holes (not shown) in the curtain 1.
In order to provide the tyres 2,3 with satisfactory buoyancy, the upper segments of the
_ c _
insides of ' the tyres are filled with a closed-cell plastics foam, for example, polyurethane foam, which is expanded in-situ. The arrangement is such that when the boom is deployed, the curtain 1 floats in an upright position and projects above the surface S of the water with a desired amount of freeboard 6. For example, such a boom may be constructed so as to have a freeboard of about 10-45cms and a draught of about 45-50cms.
The boom described above may be fabricated from recycled conveyor belting and pneumatic tyres and therefore can be produced very cheaply. It is stable and flexible, in both horizontal and vertical directions, when deployed on water. It can operate satisfactorily in adverse weather and wave conditions without bridging waves or flipping-over and, even in such conditions, fuctions adequately to contain pollutants floating on the water. •
The fence-type boom shown in Figures 4 and 5 comprises a row. of buoyancy members or floats 10 which may, for example, be pneumatic tyres with suitably enhanced buoyancy, disposed in spaced apart relation and linked together by chain 11. A curtain member 12 which may be formed from reinforced rubberised fabric material is threaded about the floa'ts in a serpentine manner so that the curtain is disposed alternately on opposite sides of the floats. The latter are fixed to the curtain at positions spaced below its upper edge so as to provide freeboard when the boom is deployed. The chain 11 linking the floats is arranged to extend through small openings in the curtain 12 where it passes between the adjacent floats 10. The overall length of the chain 11 is somewhat less than the overall length of the curtain member 12 so as to achieve the shallow serpentine shape of the latter. It
is calculated that the deeper the serpentine shape, the more differential vertical movement can take place to accommodate wave action.
Figures 6 and 7 illustrate a modification of the previous embodiment, in which the curtain member 12 extends along and is fixed to one side of the row of floats 10 and is formed with pleats 13 in the spaces between the ends of adjacent floats.
In the embodiment illustrated in Figures 8, 9 and 10, the boom is of composite construction. It is manufactured from plastics sheet material, for example, p.v.c. or polyurethane sheet material, and has buoyancy chambers 15 formed along an upper marginal portion of the curtain 16 which chambers are filled with a closed-cell plastics foam 17. Ballast, for example, a chain 18, is secured along the bottom edge of the curtain 16 so that the latter floats in an upright position with a desired amount of freeboard. The boom is afforded a concertina characteristic by producing kinks or folds 19 in the body of the curtain at spaced positions along its length. These kinks are formed by coupling together portions or buoyancy chambers of the boom spaced apart by two or more buoyancy chambers 15. The spaced portions or chambers are connected together by flexible strapping 20 extending along and fastened to the boom body. The kinking of the boom is facilitated by the use of individual buoyancy chambers 15 separated by vertical strips 21 of curtain fabric about which the boom may readily fold. The kinks 19 can be disposed on one side or both sides of the boom. The overall height of such a boom may be from 0.3m to over 2m. The length of the flexible couplings may range from 10mm-1m.
Whilst particular embodiments have been described, it will be understood that modifications can be made without departing from the scope • of the invention, as defined by the appended claims. For example, in a modification of the boom structure illustrated in Figures 8, 9 and 10, the kinks 19 are formed where boom elements of standard length are interconnected to form a longer boom. In another modification, vertical crimps may be pre-formed in the boom fabric.