FLOATING BARRAGE

Abstract: A floating barrage comprising an air-containing buoyancy member (13) and a curtain suspended from the buoyancy member (13) which curtain is maintained in approximately vertical position in the water by a ballast member (9) connected to the curtain, wherein the buoyancy member and the curtain are constituted by an envelope formed by a flexible film (4) having a lower edge (7) connected to the ballast member (9) and in which the envelope contains air in a significantly smaller amount than the amount required to inflate the envelope but sufficient to keep the envelope and the ballast floating in water with part of the envelope projecting above the water surface.

Description: Floating Barrage The present invention relates to a floating barrage comprising an air-containing buoyancy member and a curtain suspended from the buoyancy member, which curtain is maintained in an approximately vertical position in the water by a ballast member connected to the curtain. It is known to confine pollutions of lakes and seas, especially oil pollutions, by launching floating barrages on the water surface with the object of containing or encircling the pollution thereby preventing it from spreading, and in order to facilitate the depollution. Floating barrages are known in which the buoyancy member consists of a tube which is inflated before the launching. Such floating barrages suffer from the drawback that they are very voluminous, hence requiring much space during transport to the site of launching, and that they are difficult to handle. Floating barrages are also known in which the buoyancy member is formed by inflation of a tubular member in connection with the launching. Floating barrages of this type are described in e.g. SE published patent application No. 436,435, NO patent specification No. 94,595 and DE patent publication No. 2,363,500. Such an inflation is laborious and time-consuming. Furthermore, floating barrages have been developed which comprise mechanical members, such as springs, for automatic inflation of the buoyancy member after launching of the floating barrages on the water surface. Examples of this type of floating barrages are disclosed in DE patent specification No. 2,226,725, SE published patent application No. 340,593 and DK patent specification No. 139,308. Moreover, SE published patent application No. 438,343 discloses a floating barrage which consists of an envelope having a water absorbing porous material located . in its lower end, and which has a hole through which water can flow into the envelope. In launching the known floating barrage, the inflowing of water will be absorbed in the water-absorbing material, and the amount of air contained therein will be displaced to the upper portion of the envelope thereby causing this portion to act as a buoyancy member. The known floating barrage is heavy to manoeuvre and difficult to remove and dispose of after use. The object of the present invention is to provide an uncomplicated floating barrage which is easy to manufacture, transport and launch, and which can be readily destroyed after use. This object is obtained with the floating barrage according to the invention, which floating barrage is characterized in that it comprises an air-tight envelope formed by a flexible film having a lower edge connected to ' the ballast member, and that the envelope contains a significantly smaller amount of air than the amount required to inflate the film envelope but sufficient to keep the envelope and the ballast floating in water with part of the envelope projecting from the water surface. The invention is based on the discovery that only a small amount of air is required to keep a film envelope with ballast floating in the manner specified above, and that this relatively small amount of air contained in an envelope having such size so as to act as buoyancy member as well as curtain after launching on the water surface, imparts to the envelope a small increase in the volume so that only a minimum of space is required for storage and transport of the floating barrage to the site of use. The invention is further based on the discovery that after having been launched on the water, an air pocket will automatically be formed at the upper end of the envelope of such floating barrage, and that the portion located beneath will be folded up to form af curtain. For instance the envelope may consist of two welded plastic films which are connected e.g. along the edges. However, it preferably consists of a plastic film which is folded around its longitudinal axis, the folded sections of the film being interconnected, e.g. by welding along the free edges. Preferably the envelope has the form of a long tube, which is compartmented into air-tight sections by means of welding seams. Preferably these welding seams extend perpendicularly to the longitudinal axis of the tube. Thus, it is ensured that the function of the floating barrage will only be slightly affected in case of a puncture of same. The compartmentalization is preferably provided by means of double welding seams which are narrowly spaced to form pockets for stiffening members, e.g. stiffening plastic members, for buttressing the floating barrage in vertical direction. The opposite sides of the tubular element may be interconnected in spots, e.g. by spot welding, spaced from the upper edge of the floating barrage to separate the area which is to form the byoyancy member after launching and the area which is to form the curtain. Thus, this separating zone is located close to the water line of the floating barrage. To prevent rupture of the envelope during launching and/or manoeuvring of the floating barrage, a rope or belt extending in the longitudinal direction of the floating barrage may be secured to the envelope. Such a rope or belt may e.g. be disposed at the upper edge of the envelope or in the area mentioned above close to the water line of the floating barrage. The ballast may consist of a metal chain, e.g. an iron chain or a sand-filled tube, and it is suitably located in a duct extending along the lower edge of the tubular member. The envelope is preferably made from a plastic film, e.g. a polyolefine film, such as a polyethylene film having a thickness of 0,05-1 mm. As it may be practical to destroy the floating barrage after use by burning, a film material is preferably used which does not cause detrimental combustion or break-down products to be formed by thermal decomposition. The floating barrage according to the invention can be manufactured in a very simple manner, e.g. in connection with extrusion of a plastic film or from a premanufactured plastic film. In either case the manufacturing is suitably carried out by folding the plastic film along its longitudinal axis and by making the necessary weldings in the longitudinal as well as the transverse direction. The floating barrage according to the invention can e.g. be stored and transported in a folded state in transport boxes of cardboard which are constructed so as to allow the floating barrage to be pulled out of the boxes by a ship or a helicopter after having been thrown out into the water from a ship or aeroplane/helicopter. The invention will now be explained in further detail with reference to the drawing in which Fig. 1 is a perspective and partial sectional view of a preferred embodiment of a floating barrage according to the invention when floating on the water. Fig. 2 is a perspective and partial sectional view of another embodiment of a floating barrage according to the invention prior to launching. Fig. 3 is a side view of the upper portion of a further embodiment of a floating barrage according to the invention. Fig. 4 is a sectional view along the line IV-IV of the floating barrage of Fig. 3 after launching. Fig. 5 is a view from above of the floating barrage of Fig. 3 after launching. Fig. 6 is a side view of the upper part of yet another embodiment of the floating barrage according to the invention. Fig. 7 is a sectional view along the line VII-VII of the floating barrage of Fig. 6 after launching and Fig. 8 is a view from above of the floating barrage of Fig. 6 after launching. The floating barrage shown in Fig. 1 is constructed of a plastic film which is folded along its longitudinal axis 2, the folded sections being interconnected at the longitudinal edges 3 of the film in the longitudinal direction. The plastic film sections are also interconnected in a zone 4 which is located a short distance from the longitudinal axis 2 to form a longitudinal duct 5 wherein a rope 6 is disposed. Said film sections are also interconnected in the longitudinal direction in a zone 7 which is located a short distance from the longitudinal edges 3 to form a further longitudinal duct 8 wherein a ballast is disposed in the form of a sand filling 9. The walls of the longitudinal duct 8 are provided with holes 10 through which water can flow. The folded film sections are further interconnected in two parallel zones 11 and 12 which extend perpendicularly to the longitudinal axis 3 of the film. The folded film sections are not interconnected in the area between the zones 4 and 7, and when the floating barrage is placed in water the amount of air present in this zone will be concentrated in an air pocket 13 which forms the buoyancy member of the floating barrage and keeps it floating in the water with part of the air pocket and the duct 5 with the rope 6 located above the water surface. When said amount of air is uniformly distributed over the entire area between the zones 4 and 7, it will be possible to place the film sections close to each other, thus allowing long lengths of floating barrage to be placed in boxes of a relatively small volume. The floating barrage shown in Fig. 2 corresponds to the one shown in Fig. 1, and the same reference numbers have been used for designating the parts corresponding to the parts mentioned in connection with Fig. 1. The floating barrage of Fig. 2 differs from the one shown in Fig. 1 in that the two film sections are interconnected in zones 20 which are mutually separated in the longitudinal direction. Fig. 2 shows the floating barrage in a stored state before launching and having the air uniformly distributed between the two film sections. The embodiment shown in Fig. 3-5 also comprises a film 21 which is folded along its longitudinal axis, the two film sections being interconnected in the longitudinal direction in three zones 23, 24 and 25 which extend parallel to the longitudinal axis 22. In the first two zones 23 and 24 the films are interconnected in areas 26 which are relatively widely spaced, and in the third zone 25 the distance between the corresponding areas 27 is shorter. The film sections are furthermore interconnected transversely to the longitudinal axis 22 in zones 28 and 29. After launching, air pockets 30, 31 and 32 will be formed in the described floating barrage, the air pocket 32 having a greater vertical extension than the two other pockets due to the wider spacing between the zones 24 and 25 than the spacing between the zone 23 and the longitudinal axis 22. As a result of the difference in the spacings between the areas 26 and the areas 27, the horizontal extension of the air pockets is also different as it will appear from Fig. 5. In the embodiment shown in Fig. 6-8 the folded film sections are interconnected in relatively short zones 40 extending perpendicularly to the longitudinal axis 41 of the film and in zones 42, 43 which are parallel to the former zones but extend over the entire width of the floating barrage. After launching, such floating barrage will form a number of relatively large air pockets 44 extending in the longitudinal direction of the floating barrage and at the top forming vertical air pockets 45 having approximately circular cross section, see Fig. 8. The main object of interconnecting the foil sections in this area which after launching is located above the air pocket which provides the sufficient buoyancy is to reduce the amount of air in the envelope and thereby to reduce the volume of the floating barrage in a stored state.

Claims: P a t e n t c l a i m s 1. A floating barrage comprising an air-containing buoyancy member and a curtain suspended from the buoyancy member, which curtain is maintained in an approximately vertical position in the water by a ballast member connected to the curtain, c h a r a c t e r i z e d in that it comprises an air-tight envelope formed by a flexible film having a lower edge connected to the ballast member, and that the envelope contains a significantly smaller amount of air than the amount required to inflate the film envelope but sufficient to keep the envelope and the ballast floating in water with part of the envelope projecting from the water surface. 2. A floating barrage according to claim 1, c h a r a c t e r - i z e d in that the envelope consists of a plastic film which is folded along its longitudinal axis, the folded sections of the film being interconnected along the free edges. 3. A floating barrage according to claim 1 or 2, c h a r a c - t e r i z e d in that the envelope has the form of a tube which is compartmented into air-tight sections by means of welding seams. 4. A floating barrage according to claim 3, c h a r a c t e r ¬ i z e d in that the welding seams extend substantially perpendicularly to the longitudinal direction of the tube. 5. A floating barrage according to claim 4, c h a r a c t e r ¬ i z e d in that it comprises pockets containing stiffening members for buttressing the floating barrage in vertical direction. 6. A floating barrage according to any of the preceding claims, c h a r a c t e r i z e d in that the opposite sides of the envelope are interconnected in spots spaced from the upper edge of the envelope. 7. A floating barrage according to any of the preceding claims, c h a r a c t e r i z e d in that a rope or belt extending in the longitudinal direction of the floating barrage is secured to the envelope. 8. A floating barrage according to any of the preceding claims, c h a r a c t e r i z e d in that the ballast member is located in a perforated duct extending along the lower edge of the envelope. 9. A floating barrage according to claim 8, c h a r a c t e r ¬ i z e d in that the ballast member consists of a metal chain or a sand-filled tube. 10. A floating barrage according to any of the preceding claims, c h a r a c t e r i z e d in that the envelope consists of a polyolefine film.

Inventors: LEIF BERG, LEIF, BERG
Applicants: BERG MARINE AS, BERG MARINE A/S
Application year: 1990
Main classification: E02B15
IPC codes: E02B15