FENDER PROTECTIVE STRUCTURES

Abstract: An impact pad for use in absorbing impact forces wherein the pad is composed of a first outer layer of an ultra-high molecular weight material (16), an intermediate layer of elastomeric material (17) bonded to the first layer (16), a third or base layer (18) of ultra-high molecular weight material wherein the base and the elastomeric layers have a plurality of laterally and longitudinally spaced bores (25, 28) to provide the resiliency to the impact forces on the outer layer.

Description: BACKGROUND OF THE INVENTION This invention relates to an impact pad for absorbing forces and more particularly to an impact pad or fender protective system for use on a floating structure for absorbing impact forces. In the operation of docking a ship, because of the speed of approach and the swells, currents and winds, it is imperative to provide a protective docking system to reduce potential damage and impact to the ship. More particularly, an impact pad for use in docking or an impact pad or fender system for use in the hull of a first vessel that receives a second smaller vessel in open waters requires the additional consideration that both vessels interact under these complex factors and, therefore, simple expedients of large shock absorbing devices do not provide the required protection because their weight, their friction factors and their installation cost are too great for economic use. The present invention contemplates the use of a novel impact pad or fender protective device that allows for ease of installation and replacement which can be done under normal repair conditions. An impact pad of the present invention can be used as where ships are docked at wharfs and it is necessary to provide a resilient fender docking system. The impact pad of the present invention can also be used as where hovercraft are to land on a given area that needs a large resilient impact pad. A further use of the present invention is to use such impact pad in the hull of a first ship that carries within it a set of smaller crafts for ferrying operations. Wood reinforcing timbers often used in the hulls of the larger receiving ships or vessels will splinter, split and require numerous replacements. Rubber fender systems offer too much friction for use in these conditions. The present invention uses a composite impact pad that provides a low friction contact surface to minimize the high shearing forces of engagement while utilizing a novel rubber backing support which withstands effectively the impact forces encountered in such ship or vessel receiving systems to protect both vessels. SUMMARY OF THE INVENTION The present invention contemplates an impact fender system that utilizes pads in combination wherein each pad has an outer layer of ultra high molecular weight material that is bonded to an intermediate layer of elastomeric material which in turn is bonded to a third layer also composed of ultra high molecular weight material. The intermediate layer and third layer have apertures thereinto that allow the intermediate layer to absorb impact forces. BRIEF DESCRIPTION OF THE DRAWINGS Fig. l is a perspective view illustrating one form of the invention wherein the larger vessel, only partly shown, has the fenders disposed along the water level under the vessel, with a second vessel being received in the hull of such first vessel; Fig. 2 is a cross sectional view taken of the fender system on line 2-2 of Fig. l; Fig. 3 is a side elevational view of the fender system taken on line 3-3 of Fig. 2; Fig. 4 is a plan view of the fender taken in cross section on line 4-4 of Fig. 3; Fig. 5 is a side elevational view in cross section of an alternative form of the fender system; Fig. 6 is a fragmentary plan view of a portion of the fender system installed on the larger vessel showing a portion of the vessel in phantom lines; Fig. 7 is a fragmentary side elevational view of a small portion of the fender system shown mounted on the vessel taken on line 7-7 of Fig. 6. DETAILED DESCRIPTION Referring to the drawings, wherein like reference numerals designate like or corresponding parts throughout the several views, there is shown in Fig. l a portion of a ship or large vessel l0 whose hull is designated by the numeral ll. Such vessel l0 is a docking vessel with an open hull capable of lowering a door, not shown, to allow water into the hull to permit smaller vessels l2 such as landing crafts thereinto whereby the larger vessels may transport such smaller vessels for ferrying operations close to land. Located above and below the water line, as depicted in Fig. l, are a plurality of impact pads or fenders l5 extending in a horizontal direction and suitably attached to the hull of the larger vessel l0. Each fender l5 is a composite member which includes a longitudinally extending inwardly disposed (as view in the larger vessel l0) solid piece of ultra-high molecular weight polyethylene material l6, a resilient second elastomeric layer l7 and integrally attached to such second layer l7 a layer of ultra-high molecular weight polyethylene material considered a third layer l8. The first layer or outermost layer l6, as viewed from inside the larger vessel l0, has an outer surface 20 and an inner surface 2l which are substantially parallel. Such first layer is composed of an ultra-high molecular weight polyethylene which has a melt flow index less than 0.l5 measured in accordance with the test procedure of ASTM l238-65T modified by an additional 3 kilogram load. The second layer l7 has an outer surface 22 that is in abutting contact with and bonded to the inner surface 2l of the first layer l6 of the ultra-high molecular weight material. Such second layer has a plurality of rows of bores 25 which are laterally and longitudinally spaced. Such bores 25, as molded into the second layer l7, extend almost through such second layer leaving a thin layer 27 (Fig. 2) that facilitates the bonding of such second layer l7 of elastomeric material to the first layer l6 of ultra-high molecular weight material. The third layer l8 is of substantially the same thickness and material as the first layer l6 of ultra-high molecular weight material and is bonded to the second layer of elastomeric material l7 during the molding process. Such third layer l8 has a plurality of rows of bores 28 that extend completely through such layer and are in axial alignment with the bores 25 in the second layer. Such layer l8 defines a base layer and provides a rigid integrity to the composite laminate structure so that in its application to a given supporting structure, such as to the hull of a ship or to a dock which may be made of diverse materials, provides a resistive base of known reactive force to the rubber layer which, under those conditions, provides a high energy absorption rate that is controllable. If the base were rubber and attached to a supporting structure such as steel, the base would be of relatively low friction and the force, versus deflective and energy absorption of the rubber with a wet or oily surface, would be quite low and, therefore, ineffective. The open area of the bores of the second layer to the total area of the second layer would be between 30% to 60%, thus permitting sufficient bulging of the elastomeric layer. Although the preferred form of invention shows the first layer of ultra-high molecular weight material as solid, it could be perforated or have bores as the second and third layer, however, there is a risk that a sharp projection on the impacting vessel or from the second smaller vessel could catch in the bores and rip the pad if the force exceeded the strength of either the rubber or the elastomeric layer or the bond between any layers. As a preferred thickness for use of the composite laminate structure as a fender protective device for the docking of a ship, the solid ultra-high molecular weight first layer l6 is approximately l-l/4 inches (3.l75 cm) to 3/4 of an inch (l.905 cm) thick. The impact rubber or elastomeric second layer is in the range of 30 to 80 percent of the total opening depth of combined bores 28 and 25 while the thickness of the base or third layer is in the range of 70 to 20 percent of the opening depth. The respective aligned bores 25 and 28 define a chamber 30 that communicates with the area inside the hull or center portion of the vessel via small, narrow vent holes 3l that extend completely through the first layer l6 of ultra-high molecular weight material and the thin layer 27 of the elastomeric layer so that at times when the water fills the chamber 30, such water will be forced out through the vent holes 3l upon impact from exterior forces to the fender thereby giving a dampening effect that is a desirable feature in addition to the impact deflection of the rubber absorbing action of the second layer. To attach such composite laminate fender l5 to the hull of a vessel, the respective first and second layers have a bore 32-33, respectively, extending therethrough in alignment with a narrower bore 34 in the third layer (Fig. 4) defining a shoulder between bores 33 and 34 to receive the flat face of a washer 35 and the head of a nut 36 secured to the threaded head of a bolt 37 that is suitably fastened to the hull ll of the larger vessel l0. The length of the above described fenders l5 are such that it requires a plurality of horizontally aligned fenders (Fig. 6) to properly protect the hull ll of the larger boat. As seen in Fig. 6, a plurality of vertically disposed T-shaped members 40 are suitably attached to the inside of the hull ll to receive the fenders l5. Stops 4l are attached to the hull ll to limit the placement of the fenders l5 on the hull ll (Fig. 7). The invention as described above has been explained in reference to a fender system for a large vessel that receives a smaller vessel or vessels; however, the fender system or impact pad is equally applicable to a system for docking vessels or ships as well as in use for a landing pad for hovercraft which require a resilient receiving area. A further modification of the above described fender or impact pad l5 is shown in Fig. 5 which fender l5′ is constructed substantially identically to fender l5 in that it has an outer first layer l6′ made from ultra-high molecular weight material, a second or intermediate elastomeric layer l7′ with bores 25′ and a third layer l8′ also with bores 28′. Such third layer l8′ is made from ultra high molecular weight material. Such fender l5′ during the molding process is provided with suitable projections 45 which define stops which limit the movement of the impact pad or fender l5′ towards the hull ll. The stops or projections 45 have an inner layer 46 of ultra-high molecular weight polyethylene material, and an adjoining cylindrically shaped layer 47 of elastomeric material that merges with the elastomeric intermediate layer l7′. As in the first embodiment, fender l5′ has vent holes 3l′ to act as means for venting water that must be displaced where fender l5′ is under an impact loading. It will be apparent that although a specific embodiment and a certain modification of the invention has been described in detail, the invention is not limited to the specifically illustrated and described constructions since variations may be made without departing from the principles of the invention.

Claims: 1. In a fender system for inside the hull of a ship comprising an elongated fender, said fender having a first layer of ultra-high molecular weight material, a second layer bonded to said first layer, said second layer having a plurality of openings in laterally spaced and longitudinally spaced alignment, a third layer of rigid non-resilient material bonded to said second layer, said third layer having a plurality of openings in laterally and longitudinally spaced alignment with said openings in said second layer, vent holes in said fender that communicate said aligned openings with the interior of said hull for venting fluids, and means for attaching said fenders to the hull of said ship. 2. In a fender system as set forth in claim l wherein the open area of said openings of said third layer is in the range of thirty to sixty percent of the total area of said third layer. 3. In a fender system as set forth in claim 2 wherein said third layer is an ultra-high molecular weight layer. 4. In a fender system as set forth in claim 3 wherein the thickness of said second layer is in the range of one-fourth to one-half of the total thickness of said fender. 5. In a fender system as set forth in claim l wherein the thickness of said second layer is in the range of one inch to four inches thick. 6. In a fender system as set forth in claim 2 wherein said fender has stop means located in said openings that limit the movement of said first layer toward the direction of said third layer. 7. In a fender system as set forth in claim 6 wherein said stop means includes abutment means in each of said openings, and said abutment means is made from a layer of elastomeric material that is integral with said second layer that is adjacent said first layer, and said abutment means has a rigid outer end portion remote from that end portion that joins said second layer. 8. An impact pad for use in absorbing impacts comprising a composite pad with an outer layer of rigid non-resilient material, said outer layer having an outer surface and an inner surface, said pad having a second intermediate layer of elastomeric material bonded to said inner surface of said outer adjacent layer, a rigid base layer bonded to said intermediate elastomeric layer, and said elastomeric layer and said base layer having coextensive apertures extending through said base layer and substantially through said elastomeric layer to provide a resiliency to an impact force on said outer layer. 9. An impact pad as set forth in claim 8 wherein each of said coextensive apertures define a chamber, and a narrow vent bore in said composite pad communicates each chamber through said pad to the exterior of said outer surface of said outer layer. l0. An impact pad as set forth in claim 9 wherein the open area of said aperture of said base layer is in the range of thirty to sixty percent of the total area of said third layer. 11. An impact pad as set forth in claim l0 wherein the thickness of said intermediate elastomeric layer is in the range of one-fourth to one-half of the total thickness of said pad. 12. An impact pad as set forth in claim ll wherein said first layer and said base layer are made from ultra-high molecular weight material. 13. An impact pad as set forth in claim l2 wherein the thickness of said second layer of elastomeric material is in the range of one inch to five inches thick. 14. An impact fender system for use in absorbing shocks and impact forces comprising a plurality of longitudinally extending impact fenders in laterally spaced rows, each of said fenders having a plurality of pads in horizontal alignment, each pad having an outer layer of ultra-high molecular weight material, each of said pads having a second intermediate layer of elastomeric material bonded to one of the surfaces of said outer layer, each of said outer layers having the other surfaces facing exterior of said pad, a base layer bonded to each of said elastomeric layers, each of said elastomeric layers and said base layer in adjacent abutting relationship having coextensive apertures extending through said base layer and into said elastomeric layer to define a chamber which facilitates the compression and bulging of said elastomeric layer on said fender receiving an impact force, and vent holes extending through said fender in communicating said chamber exteriorly of and through said other surface of said pads.

Inventors: KRAMER, JAMES HARMON
Applicants: THE B.F. GOODRICH COMPANY
Application year: 1987
Main classification: E02B3
IPC codes: B63C1, E02B3, B63B59