US 3901753 A
Description (OCR text may contain errors)
United States Patent n91 jberg BOOM AND METHOD OF MANUFACTURING THE SAME Per ()lot Dberg, Sollentuna, Sweden  Assignee: Sanera Projecting Aktiebolag,
Bromma, Sweden 22 Filed: Nov. 28, 1973 21 Appl.No.:4l9,677
Related US. Application Data  Division of Ser. No. 129,932, March 31, 1971, Pat.
 Field of Search...6l/l F.l R:2l()/242.D|G.2l; 52/2; 138/118, 119; 156/218, 213,145,147, 65, 203, 204, 200, 20l, 227
 References Cited UNITED STATES PATENTS 2,515,806 7/1950 Spanel 156/65 3.364.632 1/1968 Isaac 52/2 3,579,994 5/1971 Preus 61/1 F 3,592,007 7/1971 Renncr 61/] F FORElGN PATENTS OR APPLICATIONS 1,243,176 8/1971 United Kingdom 61/1 F [4 1 Aug. 26, 1975 Primary ExaminerCharles E. Van Horn Assistant ExaminerDavid A. Simmons Attorney, Agent, or Firm-Woodhams, Blanchard and Flynn  ABSTRACT A method of producing a bouyant boom made of a flexible material impermeable to water and air. An elongated sheet of the flexible material is initially disposed in an unfolded position. The sheet has first and second portions disposed adjacent the opposite edges and extending longitudinally thereof, which first and second portions are separated by an intermediate portion. Expander devices are attached to the first and intermediate portions of the sheet at spaced intervals therealong, and pieces of flexible material are also disposed on said sheet at spaced intervals between the expander devices so as to extend transversely across the first and intermediate portions. The pieces are sealed along one edge thereof to said first and second portions in a direction transversely thereof. The first portion of the sheet is then folded to overlap the intermediate portion, which also causes a folding over of the pieces. The first portion is then sealed adjacent the free edge thereof to said intermediate portion to form a hoselike expandable portion, and the free edges of the pieces are also sealed together to form liquid-tight partitions which extend across the hoselike portion and divides same into chambers. The second edge portion of the sheet is permitted to freely extend from the hoselike portion to form a depending curtain.
7 Claims, 15 Drawing Figures PATENTEBAUGZSIWS 3, 901 ,753
sum 1 or 7 PATENTEUAUBZBIQYS 3 901 7513 saw 5 or Y l BOOM AND METHOD OF MANUFACTURING THE SAME This is a division of application Ser. No. D9932, filed M.|r 'il. HYl. now US. Pat. Nov 3,798,911.
The present ln ention refers to a boom and a method of manufacturing the same.
Harmful impurities floating on the surface of water must be screened-off and neutralized as quickly as possible. This is particularly true for oil slicks resulting from the intentional or unintentional release of oil from oil carrying ships. The most expedient device for screening-off oil slicks is the boom. A modern boom construction consists of one or more buoyant bodies, which hold the boom afloat on the surface of the water. Depending from the buoyant bodies down to a specific, suitable depth below the surface of the water is a curtain which is firmly connected to the buoyant bodies and which is provided at its bottom with weights to ensure that the curtain constantly occupies a substantially vertical position in the water.
The area of water surface impurified by the release of oil is often very wide for example such an area may be several kilometers in length and width. In order to impede and contain an oil belt of this magnitude, one or more chains of booms are required, the boom chains of necessity having great length and consisting of a larger number of booms of some 25 meters in length. This means that it must be possible to lay out and connect up the booms in a quick and simple manner. The individual booms should be so constructed that when it is desired to lay the booms out they can be released from their stowed condition rapidly and easily. It should also be possible to lay out the booms from a boat or a helicopter. Moreover, it should be possible, either while placing the booms in position or immedi ately afterwards, to connect the booms together to form a continuous, sufficiently long chain of booms in a simple and positive manner. The boom chain can then be towed and manouvered to enclose the oil belt in a closed ring of booms, whereafter the oil can be rendered harmless or moved to a suitable site for destruction.
The disadvantage with booms hitherto known to the art is that they are either very bulky, making it difficult to store and stow the same, or also require special working operations when laying them out on the sur face of the water. This latter disadvantage is related to the manner in which the booms are floated in the water. In order to hold the booms buoyant, different types of floats are used for example balls or inflated cushions of a plastics material for example, attached to the boom. There may be attached to the boom a hose which is inflated with a special inflating medium when the boom is layed out, and emptied of the inflating me dium when the boom, after having been in use, is rolled up or folded. The arrangement of balls or cushions requires a large storage space, while the hose arrange ment requires special working operation to be effected when laying out the booms.
The object of the present invention is to circumvent these disadvantages and the invention relates to the type of boom which includes buoyant bodies which are gncn their shape by the expansion of collapsable cavities. and is mainly charactcri/ed in that each cavity in cludes one or more expander means It is of particular importance that the oom is con structed o that In practice it can automatically and rapidly expand in direct connection with the laying out of the boom, and that the expanded boom can be coupled reliably and simply to a similar boom. In view of the increasing urgency for the care and protection of environment, the need of booms will probably be great and it is of the utmost importance that large series of booms can be manufactured in an efficient manner. The booms at present available do not fulfill all of the requirements placed thereon and it is a further object of the invention to provide a boom manufacturing method which fulfills all necessary requirements.
An embodiment of a boom according to the invention will now be described with reference to the accompanying drawings.
FIG. 1 illustrates a train of booms being towed by two boats while enclosing a small oil slick.
FIG. 2 is a perspective view of a portion of a boom according to the invention.
FIG. 3 is a horizontal sectional view of a portion of a boom and illustrates how two booms constructed according to the invention are coupled together.
FIG. 4 is a horizontal view ofa pre-worked length of material for use in constructing the boom of the invention.
FIG. 5 illustrates in section and in principle how the length of material illustrated in FIG. 4 is formed into a boom.
FIG. 6 illustrates the different working operations performed when forming the boom of the invention.
FIG. 7 illustrates in perspective a coupling effected between two booms constructed in accordance with the invention.
FIG. 8 illustrates in perspective and partially in section a portion of an expanded boom constructed in accordance with a further embodiment of the invention and placed on the surface of the water the FIGURE also showing the normal position of the boom, on the surface of the water when not subjected to lateral forces as a result of wind or wave pressure.
FIG. 9 illustrates the portion of the boom shown in FIG. 8 when the boom is subjected to lateral forces resulting from wind or wave pressure.
FIG. I0 illustrates in perspective coiling of the boom shown in FIG. 8 and 9.
FIG. II illustrates in perspective an expander means according to the invention, intended to be attached in the wall of a buoyant body of the boom of FIG. 8, the expander means being illustrated in its extended condition.
FIG. 12 illustrates in perspective an alternative em bodiment ofa frame member of the expander means of FIG. 11.
FIG. 13 is a section taken throught the line ll in FIG. II of the expander means in a compressed condi tion i.c., non-extended condition.
FIGS. I4 and I5 illustrate in section different positions for a latching member of one embodiment of a latching means according to the invention.
Illustrated in FIG. I are four booms [-4 coupled to' gether at their ends at positions 57 and being towed by their free ends 8 and 9 by two boats IO and II. The reference numeral I2 indicates an oil slick which is to be enclosed and rendered harmless.
FIG. 2 illustrates a portion of a boom ha\ing an up per. substantially cylindrical buoyant body in the form of a hose I3 and a depending curtain I4 fixedly at tachcd to the hose l3. The curtain I4 is provided at the bottom edge thereof with weights to ensure that the curtain constantly adopts a substantially vertical attitude in the water. Arranged in appropriate spaced apart relationship within the hose 13 are expander means 16, which consist of two resiliently, flexible platelike stirrup members 160 and [6b which have their opposite ends connected by a tension spring 4] which actuates said stirrup members so that said opposite ends are pulled toward one another causing the members 16a and 16b to assume a somewhat semicylindrical shape for causing expansion of the hose. Valve means 17 are arranged substantially on the upper side of the hose 13 to permit air to be introduced to inflate the hose and to release the air when the boom is rolled up or folded after use. The valve means l7 are of the type which permit air to pass therethrough but which prevent water from penetrating the interior of the hose.
The reference numerals l8 and 19 in FIG. 2 indicate depressions in the hose [3. The depressions l8 and 19 are correlated with the method for manufacturing the boom and with the fact that the hose according to the invention is divided into sections, each of which has a length L and forms a divided portion of the hose 13 as shown in FIG. 2. The division of a boom hose into connected sections which, with respect to the inner volume of the hose, are completely separated from each other. is necessary from the point of view of the necessary buoyancy of the boom. For example, if the boom hose was constructed of one continuous section and became damaged or punctured the hose is liable to become full of water and sink. Damage to one or more sections of a boom constructed in accordance with the present invention will have no great effect on the eflicieney of the boom, and a relatively large number of sections may be damaged without rendering the boom completely unservicable.
FIG. 3 further illustrates the division of the boom hose into sections L. The partitions arranged between the sections are in the form of pockets 20 which are connected to the wall of the hose [3 in an airtight manner hereinafter described. The reference numeral 21 in FIG. 3 indicates generally a first boom which is coupled to a second boom 22 through a coupling joint 23. The joint 23 is created by passing the hose of boom 21 over the end pocket 24 through a distance S and is terminated with a rope 25 attached to the mouth of the hose and passing around the same, while a snaphook means 26 is fastened to the left and (FIG. 3) of the boom 22 in a manner whereby the extended portion of the hose of boom 21 extends slightly over the boom 22. This method of coupling two booms together is illustrated more clearly in FIG. 7.
The aforementioned expander means for radially extending the boom hose are indicated by the reference numeral l6 in FIG. 3. Two such expander means have been shown for each section. A suitable position for the air valves I7 in each section has been shown with dotted circles in FIG. 3. The left end section of the boom 22, i.e.. the end provided with the snap-hook means 26, has an end pocket 27 which is suitably directed in the opposite direction to the remaining pockets 20. On the other hand. the right end pocket 28 of the boom 22 is directed in the same direction as the remaining pockets 20 and. similarly to the boom 2I. this end of the boom 22 is provided with an extension S which is terminated with a rope ferrule 29 for connecting the boom to a third boom in the manner previously described.
The method for manufacturing the boom of the invention is illustrated in FIGS. 4-6. FIG. 4 illustrates a sheet 30 of the material from which the hose and curtain of the boom are made. The sheet 30 consists of a water-tight and air-tight material, for example a plastics or rubber cloth, plastics or rubber impregnated fabric or the like. The total length Ll is equal to the length of the boom, for example 25 meters, and the width B of the sheet 30 corresponds to the total distance required to form both the hose l3 and the curtain 14 (FIG. 5). A rectangular portion having a width 51 has been clipped out of the left side of the portion of the sheet 30 forming the curtain l4 and a recess 31 has been made, for reasons hereinafter desclosed.
The first working step to be made on the pre-formed sheet 30 is to attach the valves 17, or suitable valve holder means, in the sheet. The valves or valve holders can be attached by sewing, adhesion or heat sealing, as can all subsequent component attaching operations. It is important, however, that the attachment joints are water-tight and air-tight. Attachment pockets 32 in tended as attachment means for the expander means 16, are then secured to the sheet 30 in a similar way, together with cloth pieces 33 intended to form sealing pockets for the different sections for the boom. The attachment flaps 32 and the cloth pieces 33 are only attached along their left edge surfaces. i.e. along seams 34 and 35 and at positions on the sheet 30 which correspond to the final positions for the expander means 16 and the pockets 20. The snap hook means 26 are attached to the outside of the left end of the sheet of material 30.
Subsequent to attaching the components 32, 33 aand 26, that portion of the upper part of the sheet 30 which is to form the hose I3 is folded around its centre line 36 so that the folded portions lie flat against each other. The boom hose is then finally assembled by joining together the end edge portions 37 and simultaneously forming a small part of a longitudinal seam or joint 38. The expander means 16 are then placed in position and fixed by means of the attachment flaps 32 while the longitudinal seam or joint 38 is successively formed from left to right as seen in FIG. 6. In FIG. 6 a first completed section of the hose is indicated by the reference numeral 39 to the left of the Figure, while the section being assembled is indicated by the reference numeral 40. Construction of the hose continues in stages, the attachment flaps 32 and the cloth pieces being successively placed in position prior to the longitudinal seam 38 being formed. FIG. 6 illustrates by way of example how an expander means 16 is placed between two attachment flaps 32', of which only one is shown in the Figure. The previously free edge surfaces of the attachment flaps 32' are then joined to the sheet of material 30 so as to secure the expander means 16' in the hose in a manner whereby the expander means is permitted some degree of movement therein. The expander means 16' may include a tension spring 41, FIGS. 2 and 7. The spring 41 is disengaged from the expander means l6 when placing the expander means in posi tion, and is then reconnected with the expander means to extend the hose as indicated to the left of FIG. 6.
Each pocket 20 (FIG. 3) is formed by a cloth piece 33 as illustrated in FIG. 6. A double folded edge 42 obtained with the cloth-piece 33 subsequent to folding the sheet of material 30 is then joined along a join line 43, whereafter folding of the length of material 30 is continued together with the forming of the longitudinal seam joint 38. Two previously free edges 44 and 45 of the clothpiece 33 then become clamped between parts of the folded length of material 30 and sealingly joined thereto.
Subsequent to the complete hose having been stepwise but continuously joined together in the aforementioned manner the rope ferrule 25 is then placed on the right side of the hose, as seen in the drawing, and the weights attached to the bottom edge of the boom curtain 14.
FIG. 7 illustrates how two booms are joined together and shows the rope ferrule at the right end of a boom 1 as seen in the drawing, and two spring-hook means 26 at the left end of a second boom 1'. It is important that the curtains l4 and 14" of the two booms at the position where they are joined is impermeable to oil. Consequently, the curtains l4" and M are made to overlap each other through a distance 82, this distance being obtained through the aforementioned construction of the curtain portion according to FIG. 4 and by the fact that the right end of the boom 1' is passed over the left end of the boom 1' to such an extent to the rope ferrule 25 passes into the recess 31 on the curtain 14" of the left boom I".
The spring-hook means 26, 26' (FIGS. 3, 4, 7) can be in the form of a self-locking quick coupling of known type which enables two booms to be connected and disconnected in a simple and easy manner.
The manufacturing method according to the invention enables the booms to be produced in a simple, expedicnt and inexpensive manner and a boom constructed in accordance with the method of the invention can be layed out rapidly, automatically expanded and coupled to similar booms in a simple and effective manner, to form long boom chains which build an effective enclosure against oil or other impurities. Moreover, a boom constructed in accordance with the in vention can be simply and quickly rolled-up or folded into a small volume for packaging or storage in a position of readiness.
For the purpose of towing chain of booms constructed in accordance with the invention, the towing means can be simply attached to the rope ferrule 25 and the hooking means 26. A chain of booms according to the invention can be connected up to form a complete enclosing ring by attaching the rope ferrule 25 at one free end of the boom chain to the hook means 26 at the other free end of the chain. By suitably modifying the sheet of material 30 when producing the same, it is possible to exclude the recesses 18 and I9 illustrated in FIG. 2.
Booms of large dimensions intended to be used at sea or for more comprehensive decontamination work in open water can, in rough weather be subjected to high wind and wave pressures, which cause the buoyant bodies to be unfavorably deformed. Under such conditions, the bodies are flattened by the wind and waves and pressed down against the surface of the water, thereby reducing the intended screening effect of the boom and also its buoyancy. Deformation and flattem ing of the hose may occur while the booms are being towed to ring an oil slick. allowing some of the enclosed oil to be blown or thrown by the wind and wave movement over the buoyant bodies. The escaped oil must then be collected and screenedoff in a new boom enclosure.
The tendency of the buoyant bodies used with the above described type of booms to yield to wind and wave pressure is primarily due to the construction of the expander means. When the walls of the boom are subjected to natural forces of sufficiently high magnitude the expander means (the spring 44) yields to said forces and the buoyant body is compressed. FIGS. 8-]! illustrate an embodiment which enables the buoyant bodies to extend automatically to maximum volume and to be locked in this condition by a special device which can only be released by manual activation when the booms are being rolled-up or folded after use. In FIG. 8 the reference numeral 46 indicates generally a boom consisting of a number of sections joined end to end, two sections 47 and 48 being shown. As previously described, each section 47, 48 includes a buoyant body 49 and a curtain 50 having attached at the bottom thereof weights 51.
Arranged within each section 47, 48 in the manner aforedeseribed are expander means 52 according to the invention. FIG. 8 illustrates how the boom behaves in quiet weather, while FIG. 9 illustrates how in rough weather the boom is liable to tilt and lie on one side thereof, while at the same time another side of the boom is pushed inwards by wind and wave pressure. The thus occuring forces attempt to compress the hose, and the expander means 52 must be so arranged that compression of the hose is prevented. At the same time, however, it must be possible to eliminate the effect which counteracts the compression of the boom in a simple manner, so that the boom can be easily rolled up, as illustrated in FIG. 10.
FIGS. 11-15 illustrate an embodiment of the expander means 52 according to the invention, having a frame generally indicated at 53, consisting of two frame pieces 54 and 55, a tension spring 56 and two spring attachments 57, 58. The frame pieces 54, and the spring attachments 57, 58 are suitably manufactured of a plastics material which enables them to be assembled together by heat welding. The spring attachments 57, 58 are provided with flanges 59, 60 (of which only the flange 59 is illustrated in FIG. 11) and end portions 61, 62 on the frame pieces 54, 55 engage the flanges in a fixed joint produced by heat welding for example.
The frame pieces 54, 55 may comprise plastic plates of suitable width and thickness. To provide for the necessary pivot points, the frame pieces are provided at the end portions 6|, 62 thereof and substantially in the centre thereof with thickness reducing recesses 63, which at these positions reduce the resistance of the frame pieces to bending so that hinge-like folding portions have a certain degree of resiliency are obtained.
The frame pieces 54, 55 are subjected to lateral bending forces both when compressed and when expanded and must therefore be sufficiently rigid. This rigidity can be provided for by appropriate dimensioning of the frame pieces 54, 55. It is, however, also possible to use as starting material a relatively thin bar 64, (FIG. 12) which on substantially straight portions of the frame pieces 54, 55 is provided with beads 65 to strengthen the Same against bending moments. No spe cial recesses 63, (FIG. ll) need then be provided, but that the thin bar 64 functions at the portion 66 and adjacent the end portions 6|, 62 as a hinge means.
The expander means 52 according to the invention is provided with latching means, generally indicated at 67 in FIG. 11, which prevents the expander means, and there by also the boom 46, from being pressed together as a result of lateral wind and wave pressure forces. In the embodiment illustrated in FIGS. ll, l3, l4 and the latching means 67 includes a stiff wire 68 arranged within the tension Spring 66 and provided at the bottom end with a bent portion 69 and at the other end with an eye piece 70, FIG. 13. The bent portion 69 is grouted in a plastic end piece 71, FIG. 13, the diameter of which is so adjusted with respect to an opening 72 in the spring seating 58 that a light press fit is obtained. To assist in retaining the end piece 71 in position in the spring seating 58, the end piece 71 is provided with a rivet-like head 73 and a circumferential gripping edge 74, which effectively locks the end piecesecurely inth'e spring seating 58.
Arranged in the eye member 70 is a latching piece 75, which in the embodiment of FIGS. ll, l3, l4 and 15 consist of a wire folded to form an elongated, narrow eye member having a link portion 76 which passes through the guide eye 70, and an outwardly projecting portion 77 which is slightly shorter than the elongated, narrow eye portion of the latching member 75. The fit so that an easily movable link connection is obtained between the latching piece 75 and the wire 68.
When the frame is compressed, so that the frame pieces 54, 55 are substantially parallel, the tension spring 56 is fully extended. The latching means 67 then occupies the position in the tension spring56 illustrated in FIG. 13. The latching member 75 is dimensioned to enable it to slide easily within the tension spring 56 and through an opening 78 arranged coaxially in the spring attachment 57. When the boom is laid out on the surface of the water, the expander means are released from the lateral forces to which they are sub- 2 jected in the rolled condition of the boom and the tension spring 56, via the spring attachment 57, 58, draws the end portion 61, 62 towards each other so that the frame pieces 54, 55 take the position illustrated in FIG.
11. The latent tension forces in the frame pieces 54, 55
also act in the same direction, these forces voccuring when bending along the recesses 63.
Simultaneously as the expander means 52 takes a,
between the eye 70 and the link portion 76 is very light,
eye-shaped portion of the latching member, the latching member 75 automatically falls down into the latching position illustrated in FIG. 14. FIG. 14 also illustrates with dashed lines the actual release position of the latching member 75. The force of the tension spring 56 and the length of the wire 68 are so adjusted that subsequent to the spring being fully expanded, a dis tance S is obtained, FIG. 14, which permits the latching member 75 to fall freely on either side.
If the boom 46 is subjected to lateral forces of such magnitude that the tension forces exerted by the spring 56 are overcome, the frame pieces 54, 55 are pressed together. This causes the wire 68 to be drawn down through the opening'lS so that when the distance S be comes zero and the latching member 78 abuts the spring seating 57 in,a,latching position as illustrated in FIG. 15.
Latching of the expander means 52 is thus effected fully automatically and the latching member 67 can only be released by manual activation. This is done when the boomis rolled up after use, all latching members being successively adjusted as the boom is rolled up so that the outwardly projecting portion 77 ,extends into the tension spring 56 whereupon the latching membentakes the position illustrated in FIG. 13.
When the boom is expanded or compressed it is important that satisfactory communication with the atmo- .-sphere is provided. As previously mentioned, the ex- 'is, made by. heat sealing or adhesion in a manner whereby a durable and tight joint is obtained. The frame pieces 54, 55, as an alternative to the previously described method of attachment, can be connected to the walls of the boom in a corresponding manner. Since the remainder of the boom is fully closed, the hole 78 will form a communication opening between the outer air and the interiorof the boom. The hole 78 can be made sufficiently large to provide satisfactory communication and, at the same time, may be sufficiently small to prevent appreciable penetration of water into the buoyant bodies. To provide for very rapid expansion, it may be necessary in practice to provide separate air inlet valves in the boom.
The joint between the lower spring attachment 58 and the lower vi/all ofthe boom may substantially be the same 'as that described with reference to the spring attachment 57.
A boom can be subjected to high stresses and strains from wind, salt water, cold etc. It is therefore obvious that the choice of materials must be made carefully. The plastic portions should not be brittle at low temperatures and all metal components, for example the tension spring 56, the wire 68 and the latching member 75 must be 'made of a corrosion resistant material.
It can be mentioned in addition to the aforegoing with respect to the function of a boom according to the invention that with comprehensive decontamination operations a larger or small number of booms must be connected to form a'trairi of booms which is towed at the two outer ends over the area to be decontaminated, whereby it is often necessary to join the two ends of the boom chain to fully enclose the contaminating oil or the like. In such cases it is suitable to fold the booms together in zig zag form in bundles, in a manner whereby the two ends of the boom are accessible and capable of being connected to adjacent booms before the booms are laid out on the water, so that the operation ofrlaying out the booms can be carried out continuously.
As previously mentioned, it is important in rough weather that the buoyant bodies of the boom are not compressed. This is effectively prevented by means of the latching means according to the invention.
The quadratic or rhomboidal shape of the boom 46 in the expanded position is advantageous with respect to the expansion of the boom but also affords a significant extra effect with regard to the ability of the boom to held oil or other impurities of the water surface enclosed. This extra effect is illustrated in FIG. 9, which shows how a boom has been capsized by wind and wave pressure and/or while being towed and lies on a substantially flat side 80. An adjacent side 8| is subjected in this position to the pressure from wind and waves and becomes somewhat arched as illustrated in the Figure and, together with the curtain 50 forms a screening wall which prevents the impurities and the water driven against the wall 81 from breaking over the same.
It will be understood that the frame pieces 54, 55, of the expander means 57 and the latching means 67 are not restricted to the described embodiment but can have any appropriate construction. Moreover, the invention is not restricted to the described construction of the cavities formed in the boom but that the cavities can be formed in any manner appropriate to the buoyancy of the boom.
The aforedescribed boom can be laid out rapidly, is automatically expanded and can be connected simply and effectively to form long boom chains which positively enclose oil or other impurities floating on the surface of the water. The manufacturing method of the present invention provides a simple, expedient and inexpensive method of manufacturing the boom according to the invention. The described expander means effectively prevents the boom from being compressed as a result of wind and wave pressure and, at the same time, enables the boom to be rolled up or folded together simply and rapidly to a small volume for packaging or storing in a position of readiness. In accordance with the invention there may be such embodiments at which the expanding means are to be actuated manually in order to obtain the expansion of the buoyant bodies before putting the boom into the water and in such a case locked in an expanding position.
What is claimed is:
l. A method of producing a boom or similiar bouyant body made of a material impermeable to water and air, for example rubber, plastic or impregnated fabric. and having a hoselike expandable upper portion and a curtainlike lower portion which depends into the water from the upper portion, comprising the steps of:
providing an elongated sheet of a flexible material which is impermeable to water and air, said sheet including first and second sheet portions disposed adjacent the opposite longitudinally extending edges of said sheet and extending longitudinally throughout said sheet. said sheet also including an intermediate sheet portion extending longitudinally of said sheet and disposed between said first and second sheet portions;
initially positioning said sheet so that at least the first and intermediate sheet portions are in a substantially unfolded condition;
mounting a plurality of expander devices on the intermediate sheet portion at longitudinally spaced intervals;
providing a plurality of flexible sheetlike pieces constructed from a material which is impermeable to water;
positioning said pieces at spaced intervals along said sheet so that the individual pieces extend transversely across said first and intermediate sheet portions;
sealing a transversely extending edge of said pieces to said first and intermediate sheet portions; folding said first sheet portion, so that it overlaps said intermediate sheet portion, thereby enclosing said expander devices and said pieces, the folding of said first sheet portion so as to overlap said intermediate sheet portion also causing a folding of the pieces; sealing the free edges of the pieces to one another to form a liquid-tight partition which extends completely across the hoselike portion defined by the overlapping first and intermediate sheet portions;
sealing the first sheet portion adjacent the longitudinally extending edge thereof to said intermediate sheet portion in a liquid-tight manner so as to form a hoselike bouyant body containing therein said expander devices and said liquid-tight partitions; and
permitting the second sheet portion to project freely outwardly from the hoselike bouyant body to form a downwardly depending curtain when the boom is disposed in a body of water.
2. A method according to claim 1, including the steps of providing one of said first and intermediate sheet portions with holes formed therein close to the borderline thereof, and securing air valves within said holes.
3. A method according to claim 1, including the step of maintaining said expander devices in at least a partially expanded state when the first sheet portion is longitudinally sealed to said intermediate sheet portion.
4. A method according to claim 1, wherein the pieces are initially positioned closely adjacent the expander devices.
5. A method according to claim 1, including the step of securing the expander devices to the first sheet portion after same has been folded over so as to overlap the intermediate sheet portion but prior to the first sheet portion being longitudinally sealed to the intermediate sheet portion.
6. A method according to claim 1, including the steps of folding over the first sheet portion so as to overlap the intermediate sheet portion and positioning same so that the free longitudinally extending edges of said pieces also overlap one another and are positioned in the vicinity of the free longitudinally extending edge of said first sheet portion, and then sealing the longitudinally extending free edges of the pieces and sumultaneously therewith sealing the free edge of the longitudinally extending free edge of said first sheet portion to said intermediate sheet portion so that the longitudinally extending free edges of said pieces are also sealed to the free edge of said first sheet portion.
7. A method according to claim 1, including the steps of providing a plurality of pairs of sheetlike members formed from a flexible water impermeable material, one pair of said sheetlike members being associated with each expander device. positioning one pair of said sheetlike members on said sheet so that one sheetlike member is positioned on said first sheet portion and the other sheetlike member is spaced transversely from said one sheetlike member and is positioned on said intermediate sheet portion, sealing each of said sheetlike members to its respective sheet portion along one transversely extending edge thereof, then positioning said expander device on said sheet so that it is partially engaged with said other sheetlike member, and then after said first sheet portion has been folded so as to overlap said intermediate sheet portion, then sealing the other transversely extending edges of said sheetlike members to the respective sheet portions.