FIELD OF THE INVENTION This invention relates generally to proiding anti- fouling protection for underwater objects and more specifically to a coating which can be applied to underwater objects such as boat hulls, water intake or outlet pipes, locks, cables, fish nets and the like to prevent the build-up of marine organisms on the surfaces of such objects and a method for applying such coating. The coating contains organic irritants such as the capsicum derivatives cayenne pepper, oleoresin capsicum or other organic irritants to repel the organisms which might otherwise attach themselves to submerged objects.

BACKGROUND OF THE INVENTION Previously many different products and processes have been tried in an attempt to prevent the build-up of marine organisms such as barnacles, zebra mussels and the like on the surfaces of underwater objects. The build-up of marine organisms is particularly a problem on boat hulls, fish nets, buoys, locks, derricks and water intake and outlet pipes. This has been a problem both in salt water and fresh water environments.

One example of such prior anti-fouling device is shown in ϋ S Patent No. 3,497,990 which discloses a layer of foam material having interconnected cells used 5 as a storage layer for anti-fouling compounds such as bis (tri-n butyl tin oxide) which slowly seeps out through a permeable outer cover layer to prevent the

growth of marine organisms on any underwater surface to which it is attached. However the foam is subject to damage from impact and abrasion and the use of organo- tin compound presents long term enviornmental problems. Heavy metal compounds such as tin are known to be toxic to many forms of life and remain in the environment indefinitely.

Well known anti-fouling paints are also frequently used with varying degrees of success. One of the primary defects of such paints is the short foul-free life. Secondly the paints lack durability and have low abrasion resistance. Many paints have unfavorable compatibility with the surfaces on which they are used and tend to magnify electrolytic corrosion when used over metallic surfaces. ϋ S Patent No. 3,761,334 shows another approach to the anti-fouling problem in which copper foil is attached to a boat hull with adhesive. Copper ions, a heavy metal, are toxic and tend to inhibit the growth of marine life. Therefore, use of such large amounts of copper can be detrimental to the environment.

Other patents such as U S Patent No. 3,142,283 show a boat hull enclosed by a loose cover which has either fresh water or chemical inhibitor pumped into the space between the cover and the hull. While such a concept might be used with a moored boat it would not be practical to use with a moving boat.

OBJECTS OF THE INVENTION One object of the invention to provide an easily

applied coating for underwater objects to prevent surface build-up of marine organisms thereon and which will not have a detrimental effect on the environment. Another object of the invention is to provide a simple inexpensive covering for underwater objects which is easy to apply with a minimum of equipment.

Yet another object of the invention is to provide marine organism repellent properties to present marine coatings without adversely effecting the protective properties properties of the coatings.

These and other objects of the invention will become more fully apparent in the following specification and the attached drawings.

SUMMARY OF THE INVENTION This invention is a protective covering for repelling marine organisms from the exterior of submerged objects comprising: a waterproof coating formulated to withstand continual submersion under water; the waterproof coating containing an organic irritant material having repellent properties which create a hostile environment for marine organisms in the area of the submerged object to be protected.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side elevational view of a sailboat showing one embodiment of the invention applied to the hull thereof;

FIG. 2 is a side elevation view of a sailboat turned upside down being sprayed with adhesive;

FIG. 3 is a fragmentary view of a portion of a boat

hull showing one embodiment of the invention;

FIG. 4 is a cross-sectional view taken on line 4-4 of FIG. 3;

FIG. 5 is a fragmentary view of a boat hull showing another embodiment of the invention using copper granules in the covering material;

FIG. 6 is a cross-sectional view taken of line 6-6 of FIG. 5;

FIG. 7 is a fragmentary view of a boat hull showing another embodiment of the invention using copper screen in the covering material;

FIG. 8 is a cross-sectional view taken on line 8-8 of FIG. 7;

FIG. 9 is a fragmentary view of a boat hull showing another embodiment of the covering using an unwoven mat of random copper wires in the covering material;

FIG. 10 is a cross-sectional view taken on line 10-10 of FIG. 9;

FIG. 11 is a fragmentary view of a boat hull showing another embodiment of the covering using short lengths of copper wire in random orientation in the covering material;

FIG. 12 is a cross-sectional view taken on line 12- 12 of FIG. 11; FIG. 13 is a fragmentary side elevational view of a water supply intake pipe with a crib on the inlet end illustrating another embodiment of the invention;

FIG. 14 is a fragmentary cross-sectional view of a boat hull showing another embodiment of the invention;

F1G. 15 is a fragmentary cross-sectional view of a boat hull showing another embodiment of the invention in which the hull is coated with an ablative paint; and

FIG. 16 is a fragmentary cross-sectional view of the embodiment shown in FIG. 15 after some of the ablative paint has leached away in water leaving a thinner layer of paint.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been found that the incorporation of organic compounds which are know to cause irritation into the protective coatings employed on submerged objects inhibit the growth of marine organisms. The organic compounds which have been found suitable are strong irritants which cause burning sensations when applied externally to the skin, preferably, such compounds are substantially not soluble in water. Water soluble compounds can be used but

the period of efficacy of coatings containing water soluble organic irritants will be less than coatings containing insoluble organic irritants. Mixtures of soluble and insoluble organic irritants can be used if desired. A preferred class of such compounds are those which are pungent stimuli. Such compounds are described by V. S. Govindarajan et al . in Critical Reviews in Food Science and Nutrition, volume 29, issue 6, beginning at page 435, which is incorporated by reference. In particular, known pungent compounds include derivatives from capsicums, ginger and black pepper as well as the synthetic homologs and analogs which possess sufficient pungency. Natural ϋnd synthetic pungent capsicum compounds include capsaicin, dihydrocapsaicin, norhidrocapsaicin, homodihydrocapsaicin, N-Vanillyl octanamide, N-Vanillyl nonamide, N-Vanillyl decanamide, N-Vanillyl undecamide and N-Vanillyl paaiperic acid amide. Natural and synthetic pungent spice ginger compounds include (6)-Gingerol, (6)-Shogaol, (6)-Paradol (dihdroshogaol) , Zingerone ( (O)-Paradol) , (8)-Gingerol, (10)-Gingerol, (8)-Shogaol, (10)-Shogaol, (8)-Paradol,

(10)-Paradol, and Gingediol. Natural and synthetic pungent black pepper compounds include (t,t), Piperamine (t) (dihydro-piperine) , Tetrahydropiperine, Chavicine (c,c), Isochavicine (t,c), Piperyline (t,t) (Pyroperine) ,

Piperettine (t,t,t) and 1-Oxononanyl piperidine. Each of the foregoing compounds can be substituted with branch and straight chain and unsaturated hexyl, heptyl, octyl, nonyl, decyl undecyl and dodecyl groups. Benzy substituents ^" including including 3,4-dihydroxy benzyl nonamide, 3,4- dihydroxy benzyl undecenamide, 4-hydroxy benzyl nonamide, and 4-hydroxy benzyl undecenamide may also be present on each of the foregoing groups of compounds. Particularly preferred are the capsicum compounds which are found in the capsicum genus of tropical herbs and shrubs of the night shade family which are most commonly referred to as poppers. Cayenne pepper and its oleoresin derivatives have proven effective. In addition, the isolated heat components derived from capsicums and their analogs and fatty acid derivatives may also be used. In particular, it has been found that the oleoresin capsicum derived from the cayenne pepper is particularly effective. The oleoresin, or isolated heat components, is contacted with the skin, the skin will burn. The oleoresin has advantages over the use of the cayenne pepper per se in that the oleoresin being liquid is more easily dispersed and retained in solution or suspension in the coating medium than would be solid pepper particles. Furthermore, the oleoresin is more evenly dispersed throughout the matrix so as to provide

even release of the irritant compound. However, if desired, solid pepper pieces may be dispersed within the coating and on the surface to provide the necessary irritant in the vicinity of the structure to be protected. Alternatives to the cayenne pepper and oleoresin are the naturally occurring and synthetic compounds described above including capsaicin, dihydrocapsaicin, norhidrocapsaicin, homodihydrocapsaicin, N-Vanillyl octanamide, N-Vanillyl nonamide, N-Vanillyl decanamide, N-Vanillyl undecamide and N-Vanillyl paaiperic acid amide. Further, other alkyl derivatives of these compounds may be used, including hexyl, heptyl, octyl, nonyl, decyl undecyl and dodecyl, including in all instances the straight and branch chain derivatives and the corresponding mono and polyunsaturated alkyls. Benzyl substitutions can also be used including 3,4-dihydroxy benzyl nonamide, 3,4-dihydroxy benzyl undecenamide, 4-hydroxy benzyl nonamide, and 4-hydroxy benzyl undecenamide. All of these compounds are known to cause strong burning sensations when applied to the skin. Capsaicin itself has been used in mace and as a topical ointment when highly diluted in the suitable carrier to provide a heating effect when rubbed on the skin. It is believed that the same irritation effect which causes the burning or heating sensation on the skin discourages marine

organisms from attaching themselves to a surface which has been treated with a composition containing these compounds. In addition to the foregoing compounds any other organic compounds capable of exhibiting similar activity can also be employed. The term organic irritant includes both natural and synthetic compounds.

While these compounds are not considered to be toxic, the symptoms they induce can be fatal. Thus, while it is believed that the beneficial effect is a result of creating an unfavorable environment for the marine organisms, it is possible that some or all of the effect is caused by inducing death of the organism. Regardless of the mode of action, these compounds do not pose a danger to higher life forms. When solid sources of the organic irritant are used, and in particular cayenne pepper, it may be beneficial to provide the pepper in the fibrous form which will tend to lay flatter and provide more surface area than coaxse chunks or coarsely ground pepper. Other shapes such as wafer shapes can also be employed to increase the surface area available for diffusion of the irritant from the solid pepper into the surrounding matrix or surface. Finely ground cayenne pepper can also be used, but care must be

taken to control dusting which can cause severe irritation and burns during application.

The matrix material into which the organic irritant compound will be admixed is any of those conventionally employed to protect underwater structures. The organic irritants of the present invention can be incorporated into any of a wide variety of types of coating compositions including epoxide coatings, urethane coatings, synthetic and natural coatings and the like. The particular coating composition which will form the matrix of the mixture in which the organic irritant will be dispersed or dissolved is selected depending upon the environment to which the underwater structure will be exposed.

Ablative marine coating compositions are well-known and are described in Research Disclosures, 299, pages 158-9 and 291, pages 499-500 and in Advances in Organic Coating Science technology Service 10 (Int. Conf. Org. Coat. Sci. Technol., 12th, 1986) pages 209-14. Marine coating compositions are well-known and include the marine coating compositions described in the United States Navy's Military Specifications regarding same.

The amount of organic irritant combined with the coating component is not critical and is selected to be sufficient to achieve the desired degree of anti-fouling

properties. In use, the organic irritant near the surface as a result of migration through the coating composition reaches the surface providing an inhospitable environment for organic organisms. This action is a continuous action caused by the continuous migration, diffusion, of the organic irritant from the interior of the coating to the exterior. The rate of diffusion of the organic irritant will determine the effective anti-fouling life of the coating composition. As a general rule, thicker compositions will tend to retain anti-fouling properties longer than thinner layers of the same composition

Further, numerous modifications may be made to extend the anti-fouling life of the paint. Microencapsulation of the organic irritants will reduce the rate of diffusion of the irritant by trapping the irritant in the capsules. By utilizing a combination of encapsulated and non- encapsulated irritant, it may be possible to provide an extended anti-fouling life. The non-encapsulated material will become available for anti-fouling purposes comparatively quickly while the encapsulating material will become available over longer periods of time. Furthermore, as the coated submerged object is subjected to the action of the tides, abrasion, movement through the water and the like, the surface of the paint will become worn exposing

many of the microcapsules to the water thereby releasing the irritant enhancing the anti-fouling effect of the composition.

It may be beneficial to lightly grind the coating after it has dried to expose the organic irritant in the coating so as to enhance the anti-fouling effect, especially in the period immediately after its application. Such grinding may be of particular benefit when a solid source of the organic irritant is used to enhance the diffusion of the irritant component to the surface of the article to be protected.

The use of water insoluble organic irritants such as capsaicin, cayenne pepper, oleoresin capsicum prolongs the useful life of anti-fouling surface as compared with organic irritants having a higher degree of water solubility.

In addition, it is also possible to incorporate into the coating composition other anti-fouling agents, including compounds of heavy metals. However, the use of such compounds is not preferred because of their known ecological problems.

Alternative techniques for extending the anti-fouling life of the coating composition is to use as the matrix or paint a material which ablates over time thereby

continuously exposing the new surface and hence new sources of the organic irritant.

For stationary objects, such as pipes, support structures, docks and the like, it is also possible to incorporate the irritant into a foam type structure such as that described in U.S. Patent 3,497,990. Such foam type structures will retain substantial quantities of the irritant compound within the cells for long periods of time. The combination of diffusion and ablation of the foam would offer a continuous release over extended periods of time of the organic irritant thereby providing an extended anti-fouling life. Controlled release of the irritant through such structures is also possible by selection of proper foam properties. These foam structures can formed in place or can be preformed. If preformed, the foam can be attached to the structure by any of a variety of fastening means, including adhesive and mechanical fasteners such as screws, straps, and the like.

The organic irritant can also be incorporated into other materials such as pressure sensitive tape, plastic panels or strips which can be fastened to the structure to be protected. The use of tape and other forms containing the irritant may facilitate protecting surfaces which are difficult or impossible to protect with film forming

coatings such as paint. For instance, submerged water intake and outlet piping can be protected from marine organisms by wrapping the pipe with a cover containing the organic irritant. The use of pressure sensitive tape containing the organic irritant is one example of this technique. Alternatively, flexible plastic sheets or film can be wrapped around the submerged body to be protected and held in place with mechanical fasteners to provide protection against the marine organisms. The quantities of the irritant compound to be included in the composition depends upon a variety of factors, the minimum axiiour ^« t to be used is easily determined by simple experimentation as the amount which will discourage marine organisms from attaching themselves to the surface to be protected. The maximum amount that can be used is determined by the compatibility of the organic irritant compound in the matrix. Excessive dilution of the matrix compound with organic irritant compound will have a deleterious effect in the coating properties of the matrix or film forming component. Thus the maximum amount to be incorporated will be determined by its ultimate effect on the coating composition properties.

Referring now to the drawings and in particular to

FIG. 1, a sailboat indicated generally by the numeral 10 has a hull 12, a keel 14, a rudder 16, a mast 18, a boom

20, a mainsail 22, and a genoa 24. The covering material of the invention is indicated generally by the numeral 26 and is applied in a manner which will be described later herein, to all surfaces of the boat 10 below the waterline 27.

As shown in FIG. 2 a sailboat 10 which is turned upside down is being sprayed with adhesive 28 from a spray nozzle 30 connected to an adhesive supply hose 32. All the portions of the boat 10 below the waterline 27 are coated with a layer of the adhesive 28 to form a retaining matrix for anti-fouling materials in various forms or configurations. The adhesive may be any type of waterproof adhesive with long durability when submerged either in salt water or fresh water. One preferred type of adhesive is acrylic, however others may also be quite satisfactory. A primary embodiment of the invention is shown in

FIGS. 3 and 4 in which a boat hull 12a is coated with an adhesive layer 28a by spraying as shown in FIG. 2 or by other suitable means. While the adhesive is still in the uncured state, a deposit of particles of cayenne pepper 34a (also called "red pepper") is applied to the adhesive layer. Some of the cayenne pepper particles 34a may be completely coated or enveloped by the adhesive. Other particles may be only partially coated with the adhesive but will be retained on the outer

surface of the hull 12a by the adhesive. The intense heat of the cayenne pepper 34a provides an extremely hostile environment for any marine organism that might otherwise attach to the surface. Cayenne pepper emits a burning or irritating property which actually burns human skin when contacted thereby and will repel living organisms such as barnacles, zebra mussels and other marine organisms which would otherwise attach themselves to underwater surfaces of boats, water supply intake pipes and the like. Over an extended period of time, if the repellent properties of the cayenne pepper diminish to the point where any build-up of organisms appears on the surface being protected, the surface may be recoated if necessary. FIGS. 5 and 6 show another embodiment of the invention in which a layer of adhesive 28b is a applied to a boat hull 12b. A deposit of particles of cayenne pepper 34b is applied to the adhesive layer 28b in the same manner as previously described with regard to FIGS. 3 and 4. A layer of copper granules 36 is them applied to the adhesive layer. The granules 36 are applied to the adhesive layer 28b in sufficient density as to substantially cover the entire surface of the boat hull 12b while leaving sufficient spacing between the copper granules 36 to form a permeable layer through which the repellent properties of the cayenne pepper 34b can diffuse and in cooperation with the copper granules 36 provide additional protection for the boat hull 12b. FIGS. 7 and 8 show another embodiment of the

invention in which a layer of adhesive 28c is applied to a boat hull 12c and deposit of cayenne pepper 34c is applied to the adhesive 28c. A layer 38 of copper wire screen is then applied to the adhesive layer 28c. When some types of adhesives are used, the adhesive penetrates through the interstices of the screen 38 and firmly locks the screen to the boat hull 12c. The copper screen 38 and the cayenne pepper 34c will provide an environment which is undesirable for marine organisms and therefore will prevent a build-up of such organisms on the outer surface of the boat hull 12c.

Another embodiment of the invention is shown in FIGS. 9 and 10 in which an adhesive layer 28d is applied to a boat hull 12d and then a deposit of cayenne pepper 34d followed by an unwoven mat of randomly oriented copper wires 40 held in place by the adhesive layer 28d.

FIGS. 11 and 12 show another variation in which a boat hull 12e is coated with an adhesive layer 28e and then followed by applications of cayenne pepper 34e and short chopped lengths of copper wire 42 deposited in random orientation on the adhesive layer 28e.

In any of the embodiments shown in FIGS. 5 through 12 the repellent properties of the cayenne pepper diffuses or migrates out through a permeable layer of copper applied in various configurations and cooperates with the repellent properties of the copper to provide increased anti-fouling protection for the surface to which it is applied.

The anti-foulant covering configurations shown in

any of the FIGS. 3 through 12 can also be used on other under water surfaces such as the water supply intake pipe 46 shown in FIG. 13. The pipe 46 can be located beneath the water on the bottom of oceans or inland lakes or other bodies of water. Even when located in freshwater lakes such as the Great Lakes, organisms such as the zebra mussel attach themselves to both the inside and outside of the pipe and not only clog the pipe to block the flow of water but also corrode the pipe enough to cause holes in the pipe over a period of time. The pipe 46 is typically a steel conduit which may be 5 or 6 feet, (1.52 or 1.83 m) in diameter or more.

The intake end of the pipe 46 is covered by a wooden crib 48 which is a lattice-like structure which keeps fish, logs and other debris from entering the intake pipes. The crib 48 is comprised of a series of wooden slats 50 with spaces 52 therebetween to permit the water to flow through into the intake pipe 46 in the direction of the arrow 54 while screening out debris and objects in the water from being drawn into the intake pipe 46 and thereby clog up the pipe. The zebra mussels not only attach themselves to the intake pipes but also attach themselves to the cribs and can clog up the spaces between the slats and block the flow of water into the pipes. The intake pipe in FIG. 13 is shown with its inside surface covered with an anti-fouling covering 56 and its outside surface covered with a similar anti-fouling covering 58. The anti-

fouling covering used on the pipe 46 is shown as the same covering illustrated in FIGS. 3 and 4, however any of the other covering configurations can also be used. The slats 50 of the crib 48 can also be covered on both sides by the same anti-fouling covering material used on the inside and outside surfaces of the pipe 46.

FIG. 14 shows another embodiment of the invention which is similar to the embodiment in FIGS. 3 and 4. In FIG. 14 a boat hull 12f is coated with a layer of waterproof immersible paint 60 such as an epoxy- polyamide paint as described in MilSpec MIL-P-24441A (SH) and while the paint is wet a deposit of particulate cayenne pepper 34f is applied. The cayenne pepper can be sprinkled or blown on the surface or applied in any other suitable manner. The paint serves the dual function of an adhesive for the cayenne pepper and a waterproof protective coating for the surface of the boat hull 12f. Other coatings such as immersible polyurethane compounds may also be used in the same manner as the expoxy-polyamide paint.

FIG. 15 shows a boat hull 12g which is coated with a layer of ablative paint 62 of the type described in MilSpec MIL-P-15931C except that in many applications, cuprous oxide has been eliminated from the formulation. Intermixed with the ablative paint is a quantity of oleoresin capsicum also called oleoresin red pepper which may be of the type produced by McCormick & Company, Inc. and identified as formula #608229. Oleoresin capsicum can be obtained in various heat units

depending upon the particular application for which it is to be used, and the heat generated by this product when mixed with an ablative paint creates a hostile environment to marine organisms which approach a submerged surface painted with such paint and repels the organisms from the surface without creating a toxic condition in the water surrounding the surface. Other derivatives of capsicum can also be mixed with an ablative paint to provide a repellent covering for underwater surfaces.

For the purpose of illustrating the invention, the anti-foulant materials such as the copper and cayenne pepper are shown as being applied after the adhesive layer is applied to the surface to be protected. It is also possible, if desired, to mix at least part of the anti-fouling materials with the adhesive and apply them both simultaneously. For example a dual orifice nozzle can spray adhesive from one orifice and cayenne pepper from an adjacent orifice and they can be mixed together either in the nozzle or in the stream emitted from the nozzle.

FIG. 16 shows another view of the boat hull 12g after a portion of the ablative paint has leached away leaving a thinner layer of paint 62a and exposing additional amounts of the oleoresin capsicum to the outer surface of the remaining paint which releases heat 64 to repel marine organisms in the vicinity of the surface. By using ablative paint new amounts of oleoresin are continually exposed as the paint leaches

away. Other derivatives of capsicum or other organic irritants may also be used in a mixture with the ablative paint or other matrix material.

While certain types of copper layer configurations are shown for the purpose of illustrating the invention, various other copper configuration and other organism repellents can be used without departing from the scope of the invention.