Synthetic seaweed

Synthetic seaweed for underwater installation comprises an elongate anchor and at least one sheet of flexible material adjacent the anchor. Fastening means secures a first edge portion of the sheet to the anchor along at least a portion thereof so that the sheet extends outwardly therefrom terminating at an outer boundary edge portion. Perforations are provided in the sheet whereby resistance of the sheet to underwater currents is reduced. The sheet may be cut into strips and buoyant material may be associated with the seaweed in its sheet or strip forms to increase the buoyancy of the finished product. In use, the anchor rests on the bottom of the sea and the submerged flexible sheets or strips extend upwardly therefrom. These sheets or strips sway in the ocean water thereby reducing currents in the surrounding water which promotes marine life and/or permits accretion of suspended sand and sedimentation of solid particles.

BACKGROUND OF THE INVENTION 
The present invention relates to synthetic seaweed and more particularly to 
such seaweed for use in promoting marine life and/or in building an 
underground reef whose purpose is to inhibit coastal erosion. 
Prior to the present invention, artificial seaweed constructions have been 
proposed for dealing with coastal erosion problems. For example, U.S. Pat. 
No. 3,299,640, granted Jan. 24, 1967, describes a seaweed type structure 
for influencing the sub-marine migration of material. This structure 
consists of a screen formed by a large series of filamentary plastic 
strands secured at one end to an anchoring device placed at the bottom of 
the sea. The strands are buoyant and therefore assume and retain an 
upright position thereby reducing currents in the surrounding water while 
promoting the deposition of sand and other solid materials entrained by 
the water. Also shown in the above patent is a group of individual spaced 
apart buoyant tapes secured to a rope-like anchor. In each instance the 
function of these constructions is to combat coastal erosion. 
U.S. Pat. Nos. 3,559,407 and 3,590,585, granted Feb. 2, 1971 and July 6, 
1971, respectively, also disclose artificial seaweed wherein assemblages 
of filamentary strands of foamed, stretched polyolefin are used for 
influencing the migration of material at the bottom of bodies of water, as 
in combatting coastal erosion. Entanglement of the filamentary strands is 
troublesome during manufacture, installation and use, and U.S. Pat. No. 
3,590,585 discusses several approaches to prevent such entanglement. 
Obviously, it is important that once any artificial seaweed construction is 
installed, such construction functions to perform its intended purpose. In 
the case of artificial seaweed installed under water for the purpose of 
promoting sedimentation of solid particles, it is essential that the 
seaweed be sufficiently strong to withstand the ocean forces and also 
particularly designed so that the seaweed remains free of entanglement. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a unique 
form of synthetic seaweed having high strength which is easy to make and 
effective to use for underwater installation in promoting marine life 
and/or inhibiting coastal erosion. 
Still another object of the present invention is to provide a wide range of 
buoyancies of the materials comprising the artificial seaweed in order to 
produce a product having the optimum resistance to underwater current 
flows. 
In accordance with the present invention, synthetic seaweed for underwater 
installation comprises an elongate anchor with at least one sheet of 
flexible material adjacent the anchor. Fastening means secures a first 
edge portion of the sheet to the anchor along at least a portion thereof 
so that the sheet extends outwardly therefrom terminating at an outer 
boundary edge portion. Perforations are provided in the sheet whereby 
resistance of the sheet to underwater currents is reduced. The anchor 
serves to hold the synthetic seaweed at the bottom of the sea and the 
perforated flexible sheet functions to effectively reduce ocean currents 
in the surrounding water which promotes marine life and/or causes 
sedimentation to thereby permit accretion of suspended sand. In essence, 
the synthetic seaweed herein functions to promote marine life and/or a 
buildup of the ocean bottom in the same manner as sea vegetation. 
The perforated sheet may be buoyant with or without added buoyancy secured 
to the exterior portions of the sheet. Also, the sheet may have a specific 
gravity greater than that of sea water with buoyant material applied 
thereto to provide the needed buoyancy. The buoyant material secured to 
the flexible sheet enhances the ability of the sheet to maintain an 
upright position under the water. Additionally, the perforations in the 
sheet enhance this upright positioning. 
The perforated sheet may have a series of spaced apart substantially 
parallel cuts extending from the outer boundary edge portion inwardly 
toward the anchor to thereby provide a plurality of strips each having a 
plurality of perforations therein. Tabs of buoyant material may be secured 
to at least some of the strips to enhance the buoyancy thereof or to 
provide the necessary buoyancy to maintain the strips in an upright 
position under the water. 
The anchor may comprise a cylindrical tube of flexible material closed at 
its opposite ends and filled with ballast. The flexible material forming 
the anchor may be the same as the material forming the sheet or strips, 
and the most convenient ballast is sand although other types of ballast 
may be used. 
It is preferred that the length of the sheet or each strip be within the 
range of two feet to fifteen feet, the most preferred length being four 
feet to eight feet. Also, the width of the strips may be within the range 
of one-quarter inch to six inches, with two inches to three inches being 
preferred.

DETAILED DESCRIPTION OF THE INVENTION 
Referring in more particularity to the drawings, FIG. 1 shows synthetic 
seaweed 10 for use in promoting marine life and/or inhibiting coastal 
erosion. It is well known that sea vegetation promotes the sedimentation 
of suspended sand and other solid particles to thereby cause a buildup of 
these particles in the general location of the vegetation. This is 
accomplished by the vegetation which acts as a barrier to thereby reduce 
currents in the surrounding water which permits the sedimentation of the 
water borne particles. The present synthetic seaweed functions in 
substantially the same manner and may be installed where there is an 
absence of sea vegetation to reduce water currents and thereby promote 
sedimentation of solid particles. This results in a buildup of the ocean 
bottom in the form of an underground reef whose purpose is to inhibit 
coastal erosion. Additionally, the synthetic seaweed herein functions to 
promote marine life such as the growth of natural sea vegetation. Such 
growth is believed to occur because of the reduced currents in the 
vicinity of the synthetic seaweed. Also, underwater installations of the 
synthetic seaweed herein provide a haven for fish, crustaceans, and other 
forms of marine life. 
One form of synthetic seaweed is shown in detail in FIG. 2A. Specifically, 
the seaweed 12 comprises an elongate anchor 14 with a sheet of flexible 
material 16 adjacent the elongate anchor. Stitching 18 secures a first 
edge portion 20 of the sheet 16 to the anchor 14 so that the sheet extends 
outwardly therefrom terminating at an outer boundary edge portion 22. 
Perforations 24 are provided in the flexible sheet 16 in order to reduce 
the resistance of the sheet to underwater currents, as explained more 
fully below. 
The outer boundary edge portion 22 of the perforated flexible sheet 16 may 
be provided with a strip of highly buoyant material 26, such as closed 
cell, foamed polyethylene or other similar material. The strip of buoyant 
material may be secured by adhesive or stitching or any convenient method 
and serves to enhance the overall buoyancy of the flexible sheet 16 when 
it is made of buoyant material. The sheet then has more of a tendency to 
extend upright in the water when the water current is high. Also, when the 
flexible sheet 16 is made of material having a specific gravity greater 
than sea water, the strip 26 of buoyant material provides the necessary 
buoyancy to the overall seaweed construction. The buoyant material 26 may 
be secured to one or the other sides of the outer boundary edge portion 
22, or both sides thereof depending upon the amount of buoyancy being 
built into the overall seaweed construction. 
One of more sheets 16 may be secured to the anchor 14 within the scope of 
the present invention. In each instance, however, the sheets are 
perforated and it is preferred that the perforations 24 be circular in 
shape each having a diameter of one-quarter inch to one inch. The percent 
open area of the perforated sheet may be five percent to ninety percent, 
preferably twenty-five to fifty percent. Also, other forms of perforations 
may be used, such as single slits or X's, for example. 
The flexible material comprising the sheet 16 may be a synthetic non-woven 
material which has certain advantages in the overall construction of the 
synthetic seaweed 12. A non-woven material is important since it is 
inexpensive and the edge portions do not unravel. Additionally, by 
utilizing a non-woven sheet in the manufacture of the present synthetic 
seaweed, the techniques employed to produce the finished product are quite 
simple. For example sheet 16 may be TYVEK, TY or REEMAY, all 
manufactured and sold by E. I. duPont de Nemours & Company. TY is a 
continuous filament polypropylene having high strength per unit weight, 
and is therefore preferred. TYVEK is a high density polyethylene, and 
REEMAY is a polyester. TYVEK and TY each have a specific gravity less 
than water which makes them buoyant. On the other hand REEMAY has a 
specific gravity slightly greater than water. 
Other non-woven materials that may be used include MIRIFI, manufactured by 
Celanese Corporation; BIDIM, manufactured by Monsanto Company; and SU, 
manufactured by Phillips Petroleum Company. Any other wet, dry laid, or 
needled non-woven material which when cut does not unravel and which has 
sufficient strength to withstand ocean current forces may be used. 
Preferably the weight of the sheet 16 of non-woven material is within the 
range of one-half to twelve ounces per square yard, preferably three to 
six ounces per square yard. Also, it is preferred that the tensile 
strength of the non-woven sheet 14 be such that a one inch strip thereof 
has a breaking strength of 10 to 70 pounds. 
While non-woven material is preferred, other flexible materials may also be 
used in fabricating the synthetic seaweed 12 of the present invention, 
such as wovens, films, plastics, metal foils or fiber materials, for 
example, with one requirement being that the material selected have the 
necessary strength to withstand underwater currents when installed. 
FIG. 2B illustrates another sheet form of synthetic seaweed 30 according to 
the present invention. The seaweed 30 is identical in all respects to the 
seaweed 12 except that the construction 30 does not include any buoyant 
material. Since the synthetic seaweed 30 does not include any buoyant 
material at the outer boundary edge portion 22, it is necessary that the 
material from which the perforated sheet 16 is fabricated have a specific 
gravity less than that of sea water. This will enable the sheet to extend 
upright in the water after installation. 
FIG. 3A illustrates another embodiment of the present invention wherein the 
synthetic seaweed 40 includes a plurality of strips 42. Specifically, the 
synthetic seaweed 40 includes an elongate anchor 14 similar to the anchors 
shown in FIGS. 2A and 2B. At least one sheet 44 of flexible material is 
adjacent the elongate anchor and stitching 18 functions to secure the 
sheet 44 to the anchor 14 along at least a portion thereof. The sheet 
terminates at an outer boundary edge portion 46, and perforations 48 are 
provided throughout the sheet to reduce the resistance of the sheet to 
underwater currents. Parallel cuts 50 function to separate the sheet 44 
into a series of the strips 42. The resultant structure is a plurality of 
such strips 42 each having a plurality of perforations therein. 
In the embodiment of the invention shown in FIG. 3A, the outer boundary 
portion 46 of each of one side of every other strip 42 includes a tab 52 
of highly buoyant material secured thereto. The material may be a closed 
cell, polyethylene or other similar material. Additionally, the remaining 
strips each have a tab 52 of highly buoyant material secured to the other 
side at the outer boundary edge portion. In the resultant structure the 
tabs 52 are secured to every other strip on one side thereof with tabs 52 
on the remaining strips on the opposite side. Alternatively, the tabs 52 
may be provided on the same side of every strip or both sides thereof, if 
desired. These tabs may be secured by adhesive or stitching or any 
convenient method and serve to enhance the overall buoyancy of the strips 
when the flexible sheet 44 is made of buoyant material. Also, when the 
sheet is made of materials having a specific gravity greater than sea 
water, the tabs 52 provide the needed buoyancy. 
The materials from which the sheet 44 is fabricated are the same as 
discussed above in conjunction with the embodiments of FIGS. 2A and 2B. 
The arrangement of perforations is also similar. 
FIG. 3B illustrates another strip-type synthetic seaweed 60 according to 
the present invention, which is identical to the synthetic seaweed 40 
except that no buoyant material is located at the outer boundary edge 
portion of the strips. In this particular embodiment it is important that 
the material forming the sheet 44 and strips 42 has a specific gravity 
less than that of sea water. 
In the embodiments of the invention shown in FIGS. 2A and 3A, the amount of 
buoyant material may be varied as little as one inch along the outer 
boundary portion to an amount covering up to the full length thereof. 
Closed cell, non-water absorbent foam is available in a broad range of 
densities, thicknesses, and widths, and when these materials are affixed 
to the sheets or strip the buoyancy may be varied as desired to meet the 
resistance requirements of specific underwater current forces. 
The length of the sheet 16 or the strips 42 is preferably within the range 
of two feet to fifteen feet, the most preferred range being four feet to 
eight feet. The width of the strips 42 is preferably in the range of 
one-quarter inch to six inches, with a most preferred range of two inches 
to three inches. 
The anchor 14 preferably comprises a cylindrical tube of flexible material 
closed at its opposite ends and filled with ballast 62, such as sand. The 
tube may be filled with any convenient and inexpensive ballast material, 
and the diameter thereof may be varied depending upon underwater 
conditions and the particular seaweed construction. When sand is used as 
ballast, the tube diameter may be between twelve inches and twenty-four 
inches, for example. Also, although stitches 18 are shown as the means for 
securing the sheets 16 and 44 to the anchor 14, other types of securement 
may be utilized within the scope of the invention. 
In use, one end of the anchor 14 may be closed during the manufacturing 
operation with the other end closed at the site of installation after the 
tube is filled with sand, for example. The synthetic seaweed is then 
installed as diagrammatically shown in FIG. 1 and either the sheets 16 of 
the embodiment shown in FIGS. 2A and 2B or the strips 42 of the embodiment 
shown in FIGS. 3A and 3B sway in the water currents. As such, these sheets 
or strips acts as a barrier to promote sedimentation of suspended sand and 
other solid particles entrained by the water. Ultimately this causes a 
buildup of the sea bottom and such buildup functions to inhibit beach 
erosion. Alternatively or simultaneously, underwater installations of the 
synthetic seaweed herein promote marine life by enabling nature vegetation 
to grow and/or provide havens for fish, crustaceans, and the like. The 
perforated characteristic of the synthetic seaweed substantially reduces 
the resistance of the sheet or the strip to underwater currents thereby 
enhancing the ability of the seaweed to maintain an upright position. 
Grommets 64 are provided at the ends of the anchor 14 for interconnecting 
a series of seaweed units.