Fender with leaf spring

A fender having a compact spring shape for protecting an object, such as a dock or boat, includes a mounting portion connected to a resilient leaf spring portion. The leaf spring portion is designed to collapse and absorb a substantial amount of energy upon impact with another object while a free end of the leaf spring slides along a front side of the mounting portion. In a preferred embodiment, the leaf spring portion is extruded of a high-strength abrasion-resistant plastic material having a low coefficient of friction, such as ultra high molecular weight polyethylene (UHMWPE). The leaf spring portion may include multiple access holes sized admit a tool for installing or removing the fender.

TECHNICAL FIELD

The present invention relates to fenders for protecting an object from being damaged by impact or rubbing against another object and, in particular, to an improved fender including a compact leaf spring element that is particularly useful for protecting boat hulls, docks, trains, train platforms, and various other vehicles, structures, and objects.

BACKGROUND OF THE INVENTION

Fenders (also known as rub rails, rub guards, and bumpers) are commonly used to facilitate sliding and prevent damage to a boat or other vessel when rubbing or bumping against structures, such as pilings and docks. Fenders are typically attached along the hull of a boat, but may also be attached to docks, pilings, seawalls, bridge footings, and other structures against which a vessel may rub or bump. Fenders are also used to protect other objects from damage due to rubbing and bumping—especially warehouse loading docks and land vehicles, such as truck trailers.

A fender system used with many military and commercial ships includes a length of half round steel pipe (hereinafter “split pipe”) extending along the hull and welded to the outside of hull to form a raised rib. A relatively smooth outer surface of the fender is desirable for sliding maneuvers such as docking, when the vessel is sliding along another object, such as a piling or dock. In these sliding maneuvers, any dents or discontinuities in the outer surface of the split pipe fender can inhibit a smooth sliding action by converting the desired longitudinal motion into an undesirable athwart ship motion, thereby causing the vessel to move away from the piling surface along which sliding is intended to occur. Dents in the split pipe can also cause impact loads to be concentrated at a small location on the hull, rather than dispersing loads across a relatively large area. The strength of the split pipe determines the energy absorption capability of the fender system in impact situations. When impacts occur that exceed its strength, the steel permanently deforms, leaving a dented outer surface. Such dents must be repaired to maintain a smooth sliding surface. Furthermore, the outer surface of the split pipe is typically painted and requires regular repainting and maintenance to prevent corrosion and other causes of failure, even in the absence of severe impacts.

Pleasure boats commonly have a light-duty fender system that includes strips of elastomer material seated in retainer channels or brackets along the sides of the hull. One such light-duty fender system is described in U.S. Pat. No. 2,959,146 of Erkert. Such fender systems are able to maintain a smooth sliding surface without discontinuities because the elastomer material is resilient. However, elastomer materials have a higher coefficient of friction than painted steel. Consequently, elastomer fenders do not slide as easily as split pipe fenders. Friction effects become even more pronounced when the elastomer is compressed, as during high impact conditions. The elastomer material also has limited abrasion resistance. In certain situations, the elastomer can be pulled out of its retainer, thereby making the fender system ineffective. Such fender systems also have a lower impact absorption capability than split pipe fender systems, and can allow impact forces to be transferred to the hull and cause damage.

U.S. Pat. No. 4,084,533 of Boyer describes a reversible rubrail for boats and ships that is formed of a unitary strip of extruded rubber or flexible plastic material. The rubrail includes a rear wall for connection to a boat and a pair of front walls extending from top and bottom edges of the rear wall in an arcuate shape to overlap along free ends of the front walls. The front walls are flexible and can be folded back to allow screws, bolts, or staples to be inserted through the rear wall for installation of the rubrail. Because the material of the front walls must be soft enough to be manually folded back for installation, the rubrail of Boyer would also suffer from the high coefficient of friction and low abrasion resistance of conventional elastomer strip fender systems.

The present inventor has recognized a need for a fender that can absorb a substantial amount of energy, that is highly resistant to permanent deformation and abrasion, has a low coefficient of friction, is easily installed, and requires little or no maintenance.

SUMMARY OF THE INVENTION

A fender for protecting a vehicle or object from damage includes a mounting portion and a resilient leaf spring portion connected to the mounting portion. The mounting portion and the leaf spring portion together form a compact spring having a generally P-shaped cross section. In one embodiment, the mounting portion and the leaf spring portion are integrally formed in a unitary one-piece structure by extrusion of a high-strength abrasion-resistant plastic material having a low coefficient of friction and a high impact resistance, such as an ultra high molecular weight polyethylene. In another embodiment, the leaf spring portion is removably connected to the mounting portion to allow the leaf spring portion to be replaced, when necessary.

The mounting portion of the fender includes a rear side for mounting to the object or vehicle, and a front side opposite the rear side. The mounting portion preferably includes multiple mounting holes, which may be drilled after extrusion and which are sized to receive screws or bolts for attaching the fender to an object or vessel.

The resilient leaf spring portion projects outwardly from a joint region and along the front side of the mounting portion to span over at least part of the front side. The distal end of the leaf spring portion is free to slide along the front side of the mounting portion when the leaf spring portion flexes under load. The leaf spring portion may include multiple access holes in alignment with the mounting holes of the mounting portion. The access holes admit a tool, such as a socket wrench or screwdriver, for tightening fasteners used to attach the fender to an object or vessel via the mounting holes.

Preferably the mounting portion of the fender is backed by a layer of elastomeric material interposed between the rear side of the mounting portion and the object or vessel, to provide further dampening and load distribution. Pigments or additives may be added to the plastic material to improve the fender's appearance and/or resistance to ultraviolet radiation. The surfaces of the plastic material may be textured or otherwise treated to impart radar scattering or absorbing properties desirable when the fender is used on military ships or other military equipment. In one embodiment, the fender is provided with a flat upper surface on an outer portion of the fender along the joint region, which can be aligned with the upper edges of a boat deck or dock to increase the usable area of the deck or dock. A high-friction traction material may be embedded in the flat upper surface to enhance safety by reducing slippage at the edges of the deck or dock.

In the figures, like reference numerals represent the same or similar parts or features.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1is a partial fragmentary view of a fender10in accordance with a first preferred embodiment shown mounted to a dock12.FIG. 2shows fender10mounted to a hull18of a boat20. AlthoughFIGS. 1 and 2show use of fender10in a marine setting, those skilled in the art will understand that fender10has utility in any environment or application where there is a need to protect an object from damage due to collisions with another object, regardless of whether one of the objects is stationary. For example, fenders in accordance with the various embodiments described herein are also useful for delivery trucks and vans, warehouse loading docks, automobiles, trains, train platforms, subway cars, subway platforms, pushcarts, walls, seawalls, bridge footings, locks, and any other vehicles, objects, structures, and environments in which collisions are common and in which, if not protected, the objects are subject to damage during collisions. For convenience, and without limiting the scope of the invention, the following description of preferred embodiments proceeds with reference to use of fenders in a marine environment and, specifically, in connection with a boat or dock, as shown inFIGS. 1 and 2.

FIG. 3is a front elevation view of fender10mounted to dock12.FIG. 4is an enlarged cross section view of fender10taken along line4—4of FIG.3. With reference toFIGS. 3 and 4, fender10includes a mounting portion30and a leaf spring portion40integrally formed of a unitary, one-piece construction. Mounting portion30is preferably an elongate planar strip having a rear side32that faces toward dock12and a front side34opposite rear side32and facing away from dock12. Fender10may be flexible enough along its length to conform to a slightly curved shape such as hull18(FIG. 2) when mounted thereto. Alternatively, fender10and/or mounting portion30may be shaped to conform to an irregularly-shaped object (not shown), for example by heating and bending, molding, or other fabrication or machining methods known in the art. Fender10may also be made in shapes that are not elongate strips, such as round shapes, for example (not shown).

Mounting portion30includes multiple mounting holes42extending through its thickness “t” and spaced apart along the length of fender10. Mounting holes42are sized to receive a mounting fastener48, such as a bolt or screw. Each of the mounting holes42preferably includes a countersink or a counterbore52that is deep enough so that a head or nut54of mounting fastener48does not protrude above an outer surface58of front side34, thereby preventing damage to mounting fasteners48and the underside of leaf spring portion40. The thickness t of mounting portion30will typically be dictated by the size of the bolt head or nut54and the thickness of material of the mounting portion30required to securely fasten fender10to dock12(i.e., material clamped between the head or nut54and dock12). However, other considerations such as flexibility, expected loads, durability, and aesthetics may also be considered when determining thickness t of mounting portion30. For example, thickness t may be in the range of approximately 0.25 inch (0.64 cm) for small craft to approximately 2.0 inches (5.1 cm) or more for large vessels. A preferred thickness t for seagoing vessels is approximately 1.0 inch (2.5 cm). The height of mounting portion30will be proportional to thickness t. At 1.0 inch (2.5 cm) thickness, mounting portion30would preferably have a height of approximately 6.0 inches (15.2 cm), for example. The length of mounting portion30will be sized to fit the length of dock12or boat20on which it will be used.

Leaf spring portion40projects outwardly from front side34of mounting portion30and downwardly to extend over mounting holes42and then back toward front side34of mounting portion30to terminate in a free end66. The shape of leaf spring portion40defines a compression space70located between leaf spring portion40and front side34of mounting portion30. Leaf spring portion40and free end66preferably extend along the length of fender10but may extend along only a portion thereof. A slit68divides mounting portion30and free end66. By extending over mounting holes42, leaf spring portion40tends to hide mounting fasteners48, providing an aesthetically pleasing appearance. Leaf spring portion40includes multiple access openings76that are aligned with mounting holes42and sized large enough to admit a tool (not shown), such as a screwdriver or socket wrench, for tightening or loosening mounting fasteners48, thereby facilitating installation and removal of fender10from dock12.

Fender10is formed of a resilient material that is flexible enough to allow leaf spring portion40to collapse into compression space70upon impact with an impacting object (not shown) or other applied force “F” directed toward dock12. However, leaf spring portion40is rigid enough, due to its wall thickness and the elasticity of the material from which it is made, such that it is not feasible to manually bend leaf spring portion40away from mounting portion30to expose mounting fastener48. Consequently, access openings76are particularly helpful for facilitating installation when mounting holes42are located beneath leaf spring portion40, as in the embodiments shown in the figures. Alternatively, mounting fasteners48could be located in an uncovered location, for example, along one or more flanges that could extend beyond leaf spring portion40(not shown). The phantom lines inFIG. 4show leaf spring40in a compressed position40a, with free end66atilted outwardly from front side34. Leaf spring portion40is preferably shaped as an elliptic semi-cylinder when in an unloaded condition, but can also be formed in any other shape suitable for collapsing upon application of an impact force, such as semi-cylindrical, semi-ellipsoid, hemispherical, and trapezoidal, for example.

Leaf spring portion40connects to mounting portion30at a common joint section80. Joint section80preferably extends along top edge84, and leaf spring portion40extends downwardly therefrom. However, fender10could alternatively be oriented so that joint section80extends along a bottom or side edge of fender10, with leaf spring portion40extending upwardly or laterally therefrom (not shown). The preferred orientation shown inFIGS. 3 and 4, with joint section80located along top edge84, prevents water and debris from collecting inside compression space70. To provide substantial spring action joint section80preferably has a thickness comparable to the thickness t of mounting portion30and the thickness of leaf spring portion40, but may be substantially thinner or thicker than mounting portion30and leaf spring portion40depending on the end use of fender10.

Joint section80may be integral with mounting portion30and leaf spring portion40of fender10, as shown inFIGS. 3-8. In embodiments described below with reference toFIGS. 9-12, joint section80can be decoupled and is not integrally formed of one piece construction with the leaf spring and mounting portions.

Joint section80and leaf spring portion40are sized so that upon application of impact force F (including rubbing or docking-related loads), leaf spring portion40will collapse into compression space70, as indicated by collapsed position40a. At the same time, free end66remains free to slide downwardly along front side34of mounting portion30and wipe against front side34, as indicated by position66a. The curved, P-shaped configuration of fender10allows a substantial amount of energy of impact to be absorbed in flattening of leaf spring portion40rather then being transferred directly to dock12. Concurrently, the ability of free end66to slide over front side34of mounting portion30maintains the spring action of fender10even under sustained impact forces or loads F. In this regard, the interface at slit68between free end66and front side34of mounting portion30should have a very low coefficient of friction to promote sliding. In addition, leaf spring portion40is desirably made of a material that is resistant to permanent deformation.

The amount of energy absorbed will be a function of the thickness of leaf spring portion40and compression space70, which are selected based on an assumed mass and impact velocity. For example, leaf spring portion40may have a thickness ranging between approximately 0.25 inch (0.64 cm) for small craft to approximately 2.0 inches (5.1 cm) or more for larger vessels. The thickness of compression space70may range between approximately 0.42 inch (1.07 cm) and approximately 3.4 inches (8.6 cm) or more for small and large craft, respectively. A preferred thickness of leaf spring portion40is 1.0 inch (2.5 cm) and a preferred thickness of compression space70is 1.7 inches (4.3 cm) for average size vessels.

Fender10is preferably extruded of a durable plastic material having a low coefficient of sliding friction, high abrasion resistance, and high strength characteristics, particularly modulus of elasticity (Young's modulus), tensile yield strength, and impact strength, such as a crystalline polyolefin resin. A suitable material is ultra high molecular weight polyethylene (UHMWPE), for example of the type sold under the trade name GUR™ by Ticona LLC of Summit, N.J., USA, a division of Celanese AG and specified by ASTM D4020. While other materials and fabrication techniques can also be used in the manufacture of fender10, UHMWPE has a combination of physical properties including abrasion resistance, strength, low friction, moldability, and resistance to permanent deformation, that are superior to any other material presently known to the inventor. Extrusion is a particularly efficient and inexpensive fabrication technique for the elongate P-shape of fender10. Co-extrusion of two or more materials can also be used to achieve different mechanical properties at different parts of fender10.

The combination of the compact P-shape and the resilient plastic material allows leaf spring portion40to collapse upon loading with impact force F, thereby absorbing energy that would otherwise be transferred directly to dock12or boat20. Resistance to permanent deformation also provides a spring action that tends to reflect the absorbed energy and hold apart colliding objects, which is especially useful in the context of a docking maneuver. Leaf spring portion40is preferably tough enough to withstand substantially complete compression against mounting portion30without undergoing any significant permanent deformation. As shown inFIGS. 1 and 4, an elastomeric layer92is provided between mounting portion30and dock12to dissipate and distribute impact loads, rather than concentrate them at a point on dock12. Similarly, elastomeric material can be interposed between fender10and hull18of boat20(not shown). A preferred elastomer strip92is formed of UV stabilized outdoor marine grade rubber having a hardness of approximately 65 durometer. In the event that impact forces F are great enough to cause substantially complete compression of leaf spring portion40and maximum elastic deformation of elastomer strip92, fender10will continue to absorb impact energy by permanently deforming at the location of impact, thereby further protecting dock12or boat20from damage.

The preferred embodiments are also characterized by a low coefficient of kinetic friction, which allows fender10to easily slide against another object. For example, boat20can easily slide against a piling (not shown) and boat hull18can easily slide against fender10of dock12. Preferably the plastic material of fender10has a coefficient of kinetic friction against dry polished steel of less than about 0.3. However, coefficients of kinetic friction (against dry polished steel) which are as low as possible or as high as 0.5 would also be within the scope of the present invention. Plastic materials that are useful with the preferred embodiments will typically have a coefficient of sliding friction against dry polished steel of greater than 0.05 and less than 0.5. Those skilled in the art will understand that friction characteristics are highly dependent upon the surface condition and the combination of materials that are being rubbed together. Accordingly, friction properties of fender10are quantified above in the context of dry polished steel for convenience only and without limiting the scope of the invention. Fender10may have a different coefficient of friction when sliding against materials other than dry polished steel. For example, the plastic material of fender10should also have a low coefficient of kinetic friction against itself (when dry) to facilitate the sliding motion of free end66against front side34of mounting portion, and preferably in the range of approximately 0.2±0.05. The low friction characteristic of fender10also allows the zone of compression of leaf spring portion40to travel easily along the length of fender10in the manner of a compression wave, further absorbing energy as boat20slides against a steel, wooden, concrete, or rubber-faced dock or piling.

As mentioned above, UHMWPE is the preferred material for use in fender10. Other materials with some or all of the material properties of UHMWPE would also be desirable. Some physical properties of UHMWPE are set forth in the paper titled “Ultra High Molecular Weight Polyethylene (UHMWPE)”, by Harvey L. Stein published by ASM International in Volume 2 of the Engineered Materials Handbook (1999), which paper is incorporated herein by reference. For example, UHMWPE has a modulus of elasticity (Young's modulus) at room temperature of between approximately 0.6 GPa and approximately 0.8 GPa (ASTM D638 and D6712, incorporated herein by reference). UHMWPE has a tensile yield strength ranging between approximately 21.0 MPa and approximately 22.3 MPa and ultimate tensile strength ranging between approximately 46.8 MPa and 53.7 MPa. UHMWPE also has an Izod impact strength of between approximately 70 kJ/m2and approximately 220 kJ/m2(modified ASTM D256, double 15° V-notched; and ASTM D6712, incorporated herein by reference), depending on the material composition and the fabrication method used. See, e.g., “Analysis of Contemporary Resins and Conversion Methods”, ASTM Working Group for Medical Grade UHMWPE, Oct. 15, 2001, which is incorporated herein by reference. UHMWPE is also highly abrasion resistant, hydrophobic, and chemically resistant. It accepts additives, such as UV stabilizers and fire retardants, which are useful in the preferred embodiments. Pigments can also be mixed with UHMWPE to eliminate the need to paint fender10, allowing matching of the fender's color to a boat20or dock12or for high-contrast colors and long-lasting visibility. UHMWPE can also be machined using conventional woodworking equipment, for example, to drill mounting holes42and access holes76after extrusion of mounting portion30and leaf spring portion40. A miter joint96(FIG. 1) is another example of a shape easily obtained by conventional woodworking equipment. UHMWPE surfaces can also be textured or treated to impart radar scattering or absorbing properties desirable when fender10is used in a military application requiring stealth capabilities. For example, the ultrablack surface topology described in U.S. Pat. No. 5,225,933 of Myers et al., incorporated herein by reference, could be formed on or applied to outer surface of leaf spring portion40or other parts of fender10. Skilled persons will appreciate that different surface textures may also be used, which are more suitable for manufacture by extrusion.

FIG. 5shows a front elevation view of a fender10′ in accordance with a second preferred embodiment.FIGS. 6 and 7are cross section views taken along respective lines6—6and7—7of FIG.5. With reference toFIGS. 5-7, fender10′ includes a plurality of drainage openings110formed along free edge66of leaf spring portion40′. Drainage openings110facilitate drainage of water from compression space70and further facilitate flushing or manual removal of debris that may become trapped in compression space70.

Fender10′ also includes multiple mounting holes42′, which are staggered on either side of a longitudinal centerline116of leaf spring portion40′. Mounting holes42′ and, consequently, access openings76′ are staggered so that an apex120of leaf spring portion40′ is smooth and uninterrupted by access openings76′ along the entire length of fender10′, thereby further reducing frictional forces during sliding or rubbing of fender10′ against another object, such as a piling. Staggering of mounting holes42also increases the strength and stiffness of leaf spring portion40′ along its apex120, as compared to fender10of FIG.3.

FIG. 8is a cross section view of a fender10″ in accordance with a third preferred embodiment. With reference toFIG. 8, free end66″ of leaf spring portion40″ is normally spaced apart from front side34of mounting portion30, when leaf spring portion40″ is in an unloaded condition. This configuration leaves a gap130between free end66″ and mounting portion30that causes leaf spring portion40″ to act as a cantilever beam when impact forces F are initially applied to fender10″. The cantilever beam effect can be designed to reduce the opposing reaction forces exerted against the impacting object before gap130is closed, thereby causing a more gradual deceleration of smaller impacting objects (not shown) relative to dock12. Fender10″ is, thus, capable of being flexible enough to prevent damage to smaller vessels colliding with dock12and, upon closing of gap130, becoming stiff enough to also decelerate larger vessels that collide with dock12. Gap130also improves drainage from compression space70.

FIG. 8also depicts an optional removable plug140positioned in access opening76″ to seal access opening76″ and improve the appearance of fender10″. Fender10″ is shown inFIG. 8mounted flush with a top side144of dock12(or boat20), thereby increasing the effective useable area of the top side144. To prevent persons (and vehicles) from slipping off the top side144, a traction enhancing material150is embedded in a flat upper surface84″ of fender10′.

FIGS. 9,10,11, and12are cross section views of fenders10a,10b,10c, and10dhaving leaf spring portions40a,40b,40c, and40d, respectively, detachably connected to respective mounting portions30a,30b,30c, and30d, in accordance with fourth, fifth, sixth, and seventh embodiments. With reference toFIGS. 9-12, leaf spring portions40a-dare connected to mounting portions30a-dalong an upper longitudinal margin170of mounting portions30a-d, so that leaf spring portions40a-dcan be removed for repair or replacement in the field, without requiring a new mounting portion. Fenders10a-dare attached to a structure174to be protected, such as a dock, boat, or other object. Preferably, leaf spring portions40a-dcan be removed and replaced without detaching their corresponding mounting portions from structure174. Leaf spring portions40a-dare preferably attached along the upper longitudinal margins170. However, in alternative embodiments leaf spring portions40a-dmay be attached to a different part of mounting portions30a-d, such as along a lower longitudinal margin178, for example.

With particular reference toFIG. 9, leaf spring portion40aof fender10aincludes a flange182athat abuts an upper side186of mounting portion30a. Flange182ais connected to mounting portion30aby means of one or more fasteners such as a screw188a, for example. Flange182ais preferably flush with a top surface of structure174to extend a usable topsides area of structure174, similarly to the embodiment of FIG.8. While the head of screw188ais shown inFIG. 9as extending from the top of flange182a, a counterbored hole (not shown) could be provided in an alternative embodiment for recessing the head of screw188abelow the surface of flange182a, thereby reducing a trip hazard.

Turning toFIG. 10, leaf spring portion40bof fender10bincludes a flange182bthat abuts a front side34bof mounting portion30band is connected to mounting portion30bby means of one or more fasteners, such as a screw188b. Mounting along front side34ballows the upper sides186of leaf spring portion40band mounting portion10bto be positioned flush with the top surface of structure174, thereby extending the usable topsides area of structure174. Screw188bmay optionally be countersunk or otherwise recessed (not shown) below the outer surface of leaf spring portion40bto avoid rubbing on an impacting object.

With reference toFIG. 11, leaf spring portion40cof fender10cincludes a flange182cthat extends horizontally along upper longitudinal margin170and a hangar tongue192that extends from a proximal end of flange182cdownwardly behind mounting portion30c. An elastomer layer92has a height that is less than mounting portion30cto leave a groove behind mounting portion30cnear upper longitudinal margin170. A transverse pair of fasteners188care driven through flange182cand hangar tongue192to secure leaf spring portion40cto mounting portion30c.

In fenders10a-c(FIGS.9-11), mounting portions30a-care removably fastened to structure174with mounting fasteners48along the length of mounting portions30a-c. Leaf spring portions40a-care fastened to mounting portions30a-cindependently of the connection of mounting fasteners48. Access openings76are provided in leaf spring portions40a-cin alignment with mounting holes42of mounting portions30a-c. The arrangement and independent connection of the leaf spring and mounting portions allows leaf spring portions40a-cto be detached for replacement without disturbing the connection between mounting portion30a-cand structure174or disturbing the resilient layer92interposed therebetween. The arrangement of access openings76also allows for fenders10a-cto be installed and removed as a unit, when desired, by uncoupling mounting fasteners48, without detaching leaf spring portions40a-cfrom mounting portions30a-c.

Alternatively, as shown inFIG. 12, mounting fastener48can be utilized for two purposes: to attach mounting portion30dto structure174and to secure leaf spring portion40dto mounting portion30d. Similarly to fender10c(FIG.11), leaf spring portion40dof fender10dincludes a flange182dthat extends in a horizontal direction from a curved portion202of leaf spring portion40dand along upper longitudinal margin170. A tongue206extends downwardly from flange182dinto a longitudinal groove210formed in mounting portion30d. Although groove tongue206and longitudinal groove210are arranged along top margin170, alternative configurations might involve placement of tongue206and groove210in other places, such as along lower longitudinal margin178, for example.

Longitudinal groove210is preferably an elongate channel that is deep enough to interrupt mounting hole42, but may also be less deep in alternative embodiments (not shown), in which case mounting portion30dmay include a secondary set of leaf-spring mounting holes (not shown) located adjacent mounting holes42. Longitudinal groove210is preferably a generally U-shaped channel that intersects at least some of mounting holes42intermediately of rear side32dand front side34dof mounting portion30d, creating first and second upwardly extending longitudinal ribs or tines222and224between which tongue206extends for connecting leaf spring portion40dto mounting portion30d. Tongue206and tines222and224collectively form a joint228offender10d. In an alternative embodiment (not shown) groove206could be formed in front side34dof mounting portion30dadjacent upper longitudinal margin170, forming an L-shaped step. In the various embodiments described above with reference toFIG. 12, mounting hole42preferably opens into longitudinal groove206.

In the preferred embodiment, one or more coupling holes230are formed in or drilled through tongue206and aligned with mounting hole42to receive a mounting fastener48, which couples leaf spring portion40dto both mounting portion30dand structure174. Coupling holes230may be bored through tongue206or may, alternatively, comprise downwardly opening notches (not shown) cut or formed into the lower edge of tongue206. In embodiments in which coupling holes are bounded, mounting portion30dmust be pulled away from structure174to detach leaf spring portion40dfor replacement or repair. The presence of first tine222allows mounting portion30dto remain partly supported on mounting fasteners48when detaching leaf spring portion40d. In embodiments including notches along the lower edge of tongue206, mounting fasteners48are merely loosened to allow tongue206to slide free of longitudinal groove210for detachment of leaf spring portion40d.

In each of the embodiments of fender10a-dshown inFIGS. 9-12, the corresponding mounting portion30a-dand leaf spring portion40a-dtogether form a compact P-shaped cross section that is strong, durable, and highly resilient. Any of the various materials and combinations of materials described above with reference toFIGS. 3-8can be used in connection with the two-piece fenders10a-cofFIGS. 9-12. For example, in some embodiments a low cost plastic material is used for mounting portions30a-dand UHMWPE is used for leaf spring portions40a-d. In other embodiments, both the mounting portions30a-dand leaf spring portions40a-dare made of UHMWPE. Furthermore, many of the features, modifications, and accessories described above with reference toFIGS. 3-8can be applied to fenders10a-dofFIGS. 9-12.