DESCRIPTION FENDER AND CUSHION MEMBER Technical Field [0001] The present invention relates to a cushion member for installing to a front face portion of a fender main body attached to a quay wall or the like. The present invention also relates to a fender provided with such a cushion member. [0002] In the present invention, the rear of the cushion member is referred to as the fender main body side, and the front thereof is referred to as the opposite side to the fender main body side. Background Art [0003] Fenders generally include a fender main body formed from a material with shock absorbing properties, such as rubber, and a cushion member installed to a front face portion of the fender main body (see, for example, Japanese Patent Application Laid-Open (JP-A) No. H11-43921). The cushion member of JP-ANo. H11-43921 includes a rear face plate positioned at the fender main body side, a front face plate that faces the rear face plate, a coupling piece that couples the front face plate and the rear face plate together, and a mounting portion that is installed at the rear face of the rear face plate. The cushion member is coupled to the fender main body through the mounting portion. In the cushion member of JP-A No. H11-43921, the coupling piece includes plural first direction extension portions that extend in one direction along the rear face plate and the front face plate, and plural second direction extension portions that extend orthogonally to the first direction extension portions, to give a configuration coupled together in a lattice pattern. [0004] In the exemplary embodiment of Fig. 1 to Fig. 3 in JP-A No. H11-43921, the mounting portion has a plate shape extending along the rear face of the rear face plate, and the cushion member is coupled to the fender main body through the mounting portion by passing bolts through the mounting portion from the front side of the cushion member and screwing the bolts into the fender main body. [0005] In the exemplary embodiment of Fig. 6 of JP-A No. H11-43921, the mounting portion includes a pedestal that extends out from the rear face plate toward the rear, and an attachment seat that is joined to the rear end side of the pedestal and that is disposed along the front end face of the fender main body. The pedestal has a cylindrical shape and is disposed with an axial center line direction of the pedestal in the front-rear direction. The front end portion of the pedestal is joined to the rear face of the rear face plate, and the rear end portion 1 7628383_1 (GHMatters) P99901.AU of the pedestal is joined to the front face of the attachment seat. The external diameter of the attachment seat in a direction orthogonal to the axial center line direction of the pedestal is larger than the external diameter of the pedestal. Bolt through holes are provided passing through the attachment seat in the front-rear direction at a portion of the attachment seat that is further to an outer peripheral side than the portion joined to the attachment seat. The cushion member is coupled to the fender main body through the mounting portion by passing bolts through the bolt insertion holes and screwing the bolts into the fender main body from the front of the attachment seat. [0006] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. DISCLOSURE OF INVENTION Technical Subject [0007] In JP-A No. H11-43921, the coupling piece at the inside of the cushion member is arranged in a lattice pattern that is not related to a shape of the mounting portion joined to the rear face plate of the cushion member, and a cushion member is desired that is capable of using the coupling piece to more efficiently distribute stress that is imparted from the mounting portion to the rear face plate when the cushion member bears load from the front. [0008] An advantage of the present invention is directed to providing a cushion member capable of using the coupling piece to efficiently distribute stress that is imparted from the mounting portion to the rear face plate when the cushion member bears load from the front, and to provide a fender with the cushion member installed at a front face portion of the fender main body. Solution to Subject [0009] A first aspect of the present invention is a cushion member for installation at a front face portion of a fender main body, the cushion member including a rear face plate that is positioned at a side of the fender main body, a front face plate that faces the rear face plate, coupling pieces that couple the front face plate and the rear face plate together, and a mounting portion including a rear face plate-joining portion that is joined to a rear face of the rear face plate. At least a portion of the rear face plate-joining portion, and at least a portion of the coupling pieces that are present at a position in front of the portion of the rear face plate-joining portion, extend along the rear face plate in a direction radiating out from a specific position on the rear face plate. In the vent that rear end cross-sections of the coupling 2 7628383_1 (GHMatters) P99901.AU pieces and a front end cross-section of the rear face plate-joining portion are projected onto a common projection plane, that is substantially orthogonal to an axial center line of the fender main body, in the projection plane, a surface area of a portion of the rear end cross-sections of the coupling pieces that overlap with the front end cross-section of the rear face plate-joining portion is 25% of the total surface area of the front end cross-section of the rear face plate-joining portion or greater. [00010] A second aspect of the present invention is the first aspect of the present invention, wherein, in the projection plane, the rear end cross-sections of the coupling pieces overlap with substantially all of the front end cross-section of the rear face plate-joining portion. [0011] A third aspect of the present invention is any one of the first to the second aspect, wherein the mounting portion includes an attachment seat that is connected to a rear end of the rear face plate-joining portion. [0012] A fourth aspect of the present invention is the third aspect, wherein the mounting portion includes a shaft shaped portion that extends rearward from the rear face plate, with the rear end of the shaft shaped portion connected to the attachment seat, and at least a portion of the rear face plate-joining portion extends along the rear face of the rear face plate in a direction radiating out from the shaft shaped portion. [0013] A fifth aspect of the present invention is the fourth aspect, wherein the shaft shaped portion passes through the rear face plate and couples the front face plate and the attachment seat together. [0014] A sixth aspect of the present invention is any one of the first to the fifth aspect, wherein a flange portion is provided at rear ends of the coupling pieces so as to overlap with a front face of the rear face plate. [0015] An seventh aspect of the present invention is a fender having a fender main body and the cushion member of any one of the first to the seventh aspect, wherein the cushion member is installed at a front face portion of the fender main body. Advantageous Effects of Invention [0016] According to the first aspect of the present invention, in the cushion member, when the rear end cross-sections of the coupling pieces and the front end cross-section of the rear face plate-joining portion of the mounting portion are projected onto a common projection plane, that is substantially orthogonal to the axial center line of the fender main body, the surface area in the projection plane of a portion of the rear end cross-sections of the coupling pieces that overlap with the front end cross-section of the rear face plate-joining portion is 3 7628383_1 (GHMatters) P99901.AU 25% of the total surface area of the front end cross-section of the rear face plate-joining portion or greater. This thereby enables stress imparted to the rear face plate from the rear face plate-joining portion, when the cushion member bears load from the front, to be efficiently distributed by the coupling piece. This thereby enables the strength required in each portion of the cushion member to be set comparatively low. As a result, a reduction in weight of the cushion member and a reduction in material cost of the cushion member are achievable. The numerical value range 25% or above has been identified as a range that obtains a significant stress distribution effect, by the inventors making various changes to the structure of the cushion member and performing repeated computer simulations and actual experiments etc. In the present invention, the axial center line of the fender main body is an axial line in the front-rear direction that passes through a central position of the front end face and the rear end face of the fender main body. For example, in cases in which the fender main body is a substantially circular cylindrical shape, the axial center line of the fender main body is effectively the axial center line of the circular cylinder. "The common projection plane is substantially orthogonal to the axial center line of the fender main body" indicates orthogonal direction (normal direction) to the projection plane may be slightly tilted (preferably by 50 or less) with respect to the axial center line of the fender main body. [0017] Additionally, according to the first aspect of the present invention, due to the rear face plate-joining portion, and the coupling pieces that are present at a position in front of the rear face plate-joining portion, extending along the rear face plate in a direction radiating out from a specific position on the rear face plate (for example a position corresponding to the axial central position of the fender main body), stress imparted to the rear face plate from the rear face plate-joining portion, when the cushion member bears load from the front, is distributed over a wide range in a radiating shape along the rear face plate-joining portion and the coupling pieces. This thereby enables stress imparted to the rear face plate to be even more efficiently distributed. [0018] According to the second aspect of the present invention, in the projection plane, preferably the rear end cross-sections of the coupling pieces overlap with substantially all of the front end cross-section of the rear face plate-joining portion. In the present invention, substantially all of the front end cross-section of the rear face plate-joining portion indicates 50% or more, and preferably 75% or more, of the front end cross-section. Adopting such a configuration enables stress imparted to the rear face plate from the rear face plate-joining portion, when the cushion member bears load from the front, to be even more efficiently distributed by the coupling piece. 4 7628383_1 (GHMatters) P99901.AU [0019] According to the third aspect of the present invention, due to the mounting portion including the attachment seat that is connected to the rear end of the rear face plate-joining portion, the rear end side of the rear face plate-joining portion can be reliably coupled to the fender main body through the attachment seat. Moreover, due to the rear end side of the rear face plate-joining portion being supported by the attachment seat, a high support rigidity of the cushion member by the rear face plate-joining portion is achieved. [0020] According to the fourth aspect of the present invention, due to providing the shaft shaped portion that extends rearward from the rear face plate with the rear end of the shaft shaped portion connected to the attachment seat, the cushion member is also supported by the shaft shaped portion, and accordingly the stress imparted to the rear face plate from rear face plate-joining portion, when the cushion member bears load from the front, is alleviated. Due to the rear face plate-joining portion extending from the shaft shaped portion in a radiating direction, the stress of the rear face plate alleviated by the shaft shaped portion is further distributed over a wide range along the rear face plate-joining portion in a shape radiating out from the shaft shaped portion. As a result, it is possible to set the strength required for each of the portions of the cushion member lower. [0021] According to the fifth aspect of the present invention, due to the shaft shaped portion passing through the rear face plate and coupling the front face plate and the attachment seat together, stress imparted to the rear face plate from the rear face plate-joining portion, when the cushion member bears load from the front, can be alleviated even more. [0022] According to the sixth aspect of the present invention, due to providing the flange portion at the rear ends of the coupling pieces so as to overlap with the front face of the rear face plate, the contact surface area between the rear end sides of the coupling pieces and the front face of the rear face plate is increased, thereby raising the joining strength of the coupling pieces to the rear face plate. Due to the rigidity of the rear face plate being raised by the flange portion, this enables the strength of the rear face plate itself to be set comparatively low. In cases in which the flange portion is provided to the respective rear ends of the coupling pieces, the rear end cross-sections of the coupling pieces projected onto the projection plane may include the flange portion, or may lack the flange portion. [0023] According to the seventh aspect of the present invention, in the fender, due to the cushion member of the present invention being installed at the front face portion of the fender main body, a configuration of the fender can be achieved in which the stress imparted to the rear face plate from rear face plate-joining portion, when the cushion member bears load from the front, can be efficiently distributed by the coupling piece. Moreover, it is possible to 5 7628383_1 (GHMatters) P99901.AU configure the fender overall with a comparatively low weight and low cost configuration. Moreover, by making the fender lighter in weight, the strength required for a fixing structure to fix the fender to a fender installation face, such as a quay wall, can be set comparatively low. BRIEF DESCRIPTION OF DRAWINGS [0024] Fig. 1A is a cross-section perspective view of a fender provided with a cushion member according to an exemplary embodiment, and illustrates a cross-section taken along line IA-IA of Fig. 1D. Fig. 1B is a see-through cross-section perspective view illustrating a state in which the front face plate of the cushion member in Fig. 1A has been made see-through. Fig. 1C is a perspective view of a mounting portion of the cushion member of Fig. 1A. Fig. 1D is a front view of an ID portion of Fig. 1B (in the vicinity of a mounting portion coupling region of a rear face plate of the cushion member). Fig. 1E is a cross-section taken along line IE-IE in Fig. 1D. Fig. iF is a cross-section taken along line IF-IF in Fig. 1D. Fig. 2A is a partial see-through cross-section perspective view of a cushion member provided with a cushion member according to a Comparative Example, illustrating a cross-section running along an axial center line direction of the fender main body, and illustrating a state in which the front face plate of a cushion member has been made see-through. Fig. 2B is front view of an IIB portion of Fig. 2A (in the vicinity of a mounting portion coupling region of a rear face plate of the cushion member). Fig. 2C is a cross-section taken along line IIC-IIC of Fig. 2B. Fig. 3A is a diagram illustrating a distribution of stress on a rear face plate of an Example. Fig. 3B is a diagram illustrating a distribution of stress on a rear face plate of a Comparative Example. BEST MODE FOR CARRYING OUT THE INVENTION [0025] Explanation follows regarding an exemplary embodiment. In the following exemplary embodiment, an example is given of application of the present invention to a fender provided with a fender main body having a substantially circular cylindrical shape, however the present invention is applicable to other fenders (for example arch shaped fenders). [0026] Exemplary Embodiment 6 7628383_1 (GHMatters) P99901.AU A fender 1 includes a fender main body 2 for attaching to a fender installation face (not illustrated in the drawings) such as a quay wall, and a cushion member 10 provided at a front face portion of the fender main body 2. The fender main body 2 is made from a material with shock absorbing properties, such as rubber. In the present exemplary embodiment, the fender main body 2 is formed in a substantially circular cylindrical shape, with an end face at one end side in an axial center line direction of the circular cylindrical shape (the rear end face) disposed so as to oppose the fender installation face, and is fixed to the fender installation face using a fixing means, such as bolts (not illustrated in the drawings). A mounting portion 20 provided at the rear face of the cushion member 10 is contiguous with an end face at the other end side in the axial center line direction of the fender main body 2 (the front end face). As illustrated in Fig. 1A, Fig. 1B, the fender main body 2 is formed in a tapered shape in which the inner diameter and the outer diameter become smaller on progression toward a front end side. An embedded member 3 formed from a rigid material, such as steel, is embedded inside the fender main body 2 along the front end face. Plural female screw holes 4 (Fig. 1E) are provided at the embedded member 3 at specific intervals around the circumferential direction of the front end face of the fender main body 2. [0027] As illustrated in Fig. 1A, Fig. 1B, and Fig. 1D to Fig. iF, the cushion member 10 includes a rear face plate 11 positioned on an fender main body 2 side, a front face plate 12 that faces the rear face plate 11, coupling pieces 14 that couple the rear face plate 11 and the front face plate 12 together, and the mounting portion 20 that is joined to the rear face of the rear face plate 11. The front face plate 12 is disposed at a separation from the rear face plate 11 toward the front. The rear face plate 11 configures a rear face of the cushion member 10, and the front face plate 12 configures a front face of the cushion member 10. The peripheral edges of the rear face plate 11 and the front face plate 12 are coupled together by side face plates 13. Due to the side face plates 13, the cushion member 10 is imparted with a higher rigidity, and ingress of sea water or the like into the cushion member 10 is prevented. The coupling pieces 14 are disposed at the inside of the cushion member 10, surrounded by the rear face plate 11, the front face plate 12, and the side face plates 13. In the present exemplary embodiment, a substantially central portion of the rear face plate 11 configures a mounting portion coupling region 1la that is joined to the mounting portion 20. A pad (not illustrated in the drawings) made from a material with shock absorbing properties, such as an ultra-high molecular weight polyethylene plate having an average molecular weight by mass of 500,000 or greater, is attached to the front face of the front face plate 12. Details regarding the coupling pieces 14 are given later. 7 7628383_1 (GHMatters) P99901.AU [0028] In the present exemplary embodiment, the mounting portion 20 includes a pedestal 21 that extends out rearwards from the rear face plate 11, and an attachment seat 22 that is connected to a rear end side of the pedestal 21 and that is disposed along the front end face of the fender main body 2. In the present exemplary embodiment, the pedestal 21 includes a shaft shaped portion 21a that extends out rearwards from the rear face plate 11 and that has a rear end connected to the attachment seat 22, and plural rear face plate-joining portions 21b that are disposed at a periphery of the shaft shaped portion 21a and are joined to the rear face of the rear face plate 11. A rear end of each of the rear face plate-joining portions 21b is connected to the attachment seat 22. In the present exemplary embodiment, a front end cross-section of each of the rear face plate-joining portions 21b is a cross-section of each of the rear face plate-joining portions 2 lb running along the rear face of the rear face plate 11. Namely, in the present exemplary embodiment, front end faces of the rear face plate-joining portions 21b in Fig. 1C (the end faces on the opposite side to the attachment seat 22) each corresponds to the front end cross-section of the rear face plate-joining portion of claim 1. [0029] In the present exemplary embodiment, the shaft shaped portion 21a has a substantially circular cylindrical shape, and is disposed with an axial center line direction of the circular cylindrical shape running substantially along the front-rear direction, in a substantially coaxial shape to the fender main body 2. In the present exemplary embodiment, as illustrated in Fig. 1E, a front end side of the shaft shaped portion 21a is disposed inside the cushion member 10, and is joined to a rear face of the front face plate 12 by a joining means, such as welding. A rear end side of the shaft shaped portion 21a extends toward the outside and to the rear of the cushion member 10, through an opening 1 lb provided at a substantially central portion of the mounting portion coupling region 11 a of the rear face plate 11. Namely, in the present exemplary embodiment the shaft shaped portion 21a passes through the rear face plate 11, and is coupled to the front face plate 12 and to the attachment seat 22. An inner peripheral edge of the opening 1 lb is joined by a joining means, such as welding, to an outer peripheral edge partway along the axial center line direction of the shaft shaped portion 21a. [0030] The attachment seat 22 in the present exemplary embodiment is substantially circular plate shaped, and is disposed with a substantially coaxial shape to the shaft shaped portion 21a, with a front face of the attachment seat 22 joined to the rear end of the shaft shaped portion 21a. The external diameter of the attachment seat 22 is greater than the external diameter of the shaft shaped portion 21a. Plural bolt insertion holes 22a are provided in a portion of the attachment seat 22 further to the outer peripheral side than a portion of the 8 7628383_1 (GHMatters) P99901.AU attachment seat 22 joined to the shaft shaped portion 21a, at specific intervals around the circumferential direction thereof. The bolt insertion holes 22a are provided so as to overlap with the respective female screw holes 4 of the embedded member 3. The mounting portion 20 is coupled to the front end face of the fender main body 2 by disposing the attachment seat 22 along the front end face of the fender main body 2, and screwing bolts 5 into each of female holes 4 through the respective bolt insertion holes 22a from the front side of the attachment seat 22. The method of coupling the mounting portion 20 to the fender main body 2 is not limited thereto. [0031] In the present exemplary embodiment, the rear face plate-joining portions 21b extend along the rear face of the rear face plate 11 in directions radiating out from the shaft shaped portion 21a. In the present exemplary embodiment, plural of the rear face plate-joining portions 21b are provided at intervals around the circumferential direction of the shaft shaped portion 21a. The number of the rear face plate-joining portions 21b is from 3 to 24, and is preferably from 6 to 12, and more preferably from 6 to 8. The opening angle 0 between rear face plate-joining portions 21b, 21b that are adjacent to each other in the circumferential direction of the shaft shaped portion 21a is from 150 to 1200, and is preferably from 30' to 600, and more preferably from 450 to 600 (Fig. 1C). In the present exemplary embodiment, in consideration of ease of operation to screw in the bolts 5, each of the rear face plate-joining portions 21b are disposed at positions separated at specific intervals around the circumferential direction from the respective bolt insertion holes 22a. In the present exemplary embodiment, as illustrated in Fig. 1C, the rear face plate-joining portions 21b are respectively disposed at substantially the middle between the bolt insertion holes 22a, 22a adjacent to each other in the circumferential direction. Note that the placement of the rear face plate-joining portions 21b is not limited thereto. For example, two or more of the rear face plate-joining portions 21b may be disposed between the bolt insertion holes 22a, 22a adjacent to each other in the circumferential direction. [0032] In the present exemplary embodiment, a length in the radiating direction of each of the rear face plate-joining portions 21b from the shaft shaped portion 21a along the rear face of the rear face plate 11 (sometimes referred to below simply as the length of the rear face plate-joining portions 21b) is substantially the same as a size in the same direction of the portion of the attachment seat 22 further to the outer peripheral side than the portion of the attachment seat 22 joined to the shaft shaped portion 21a. Note that the length of each of the rear face plate-joining portions 21b is not limited thereto. [0033] In the present exemplary embodiment, each of the rear face plate-joining portions 9 7628383_1 (GHMatters) P99901.AU 21b has a substantially rectangular plate shape, has an extension direction of the plate plane that is substantially orthogonal to the rear face of the rear face plate 11 and is a direction substantially radiating out from the shaft shaped portion 21a, and is disposed at the periphery of the shaft shaped portion 21 a in the space between the rear face plate 11 and the attachment seat 22. An end portion of each of the rear face plate-joining portions 21b on the radiating direction center side is joined to the outer peripheral face of the shaft shaped portion 21a, and the rear end portion of each of the rear face plate-joining portions 21b is joined to a portion of the front face of the attachment seat 22 further to the outer peripheral side than the portion of the attachment seat 22 joined to the shaft shaped portion 21a. The mounting portion 20 may be configured by integrally molding the shaft shaped portion 21a, the rear face plate-joining portions 21b, and the attachment seat 22 together from the beginning, or may be integrally joined by joining means, such as welding, after forming at least one of these portions separately to the other portions. The front end portion of each of the rear face plate-joining portions 21b is joined to the rear face of the rear face plate 11 by a joining means, such as welding. [0034] In the present exemplary embodiment, the coupling pieces 14 are each configured by substantially strip shaped plate that is disposed with a plate plane in a direction substantially orthogonal to the front face of the rear face plate 11 and to the rear face of the front face plate 12. A rear end side of each coupling piece 14 is joined to the front face of the rear face plate 11, by welding or the like, and a front end side of each coupling piece 14 is joined to the rear face of the front face plate 12, by welding or the like. In the present exemplary embodiment, flange portions 15 are formed to the rear end side of each coupling piece 14, and project out to the sides from the coupling piece 14 along the front face of the rear face plate 11. Due to the flange portions 15 overlapping with the front face of the rear face plate 11, the contact surface area between the rear end side of each coupling piece 14 and the front face of the rear face plate 11 is increased, thereby raising the joint strength of the coupling pieces 14 to the rear face plate 11. In consideration that the rigidity of the rear face plate 11 is raised by the flange portions 15, the strength of the rear face plate 11 itself may be set comparatively low. Flange portions projecting out to the sides from the coupling pieces 14 along the rear face of the front face plate 12 may also be provided at the front end side of each coupling piece 14. In the present exemplary embodiment, a cross-section at the rear end of the coupling piece 14 is a cross-section of the coupling piece 14 that runs along the front face of the rear face plate 11. In the present invention, the rear end cross-section of each coupling piece 14 may include the flange portions 15, or may lack the flange portions 15. 10 7628383_1 (GHMatters) P99901.AU [0035] In the present exemplary embodiment, the portions of the coupling pieces 14 disposed at the mounting portion coupling region 11a of the rear face plate 11 configure radiating direction extension portions 14a that extend from a peripheral edge portion of the opening 1 lb in radiating directions. There are the same number of radiating direction extension portions 14a provided as the number of the rear face plate-joining portions 21b of the mounting portion 20, and they are respectively disposed at positions where the front of the rear face plate-joining portions 2 lb are present, with the rear face plate 11 interposed therebetween. End portions at the radiating direction central side of each of the radiating direction extension portions 14a are joined by a joining means, such as welding, to the outer peripheral face of the front end side of the shaft shaped portion 21a disposed inside the cushion member 10. [0036] In the present invention, in the event that a rear end cross-section of each of the radiating direction extension portions 14a, and the front end cross-section of each of the rear face plate-joining portions 21b are projected onto a common projection plane, which is substantially orthogonal to the axial center line of the fender main body 2, a surface area of the portion of the rear end cross-section of each of the radiating direction extension portions 14a overlapping, in a projection plane, with the front end cross-section of each of the rear face plate-joining portions 21b is 25% or greater of the total surface area of each of the front end cross-section of the overlapped rear face plate-joining portions 21b. In particular, preferably each of the radiating direction extension portions 14a overlaps with substantially all of the front end cross-section of each of the rear face plate-joining portions 21b. In the present invention, substantially all of the front end cross-section of each of the rear face plate-joining portions 21b refers to a front end cross-section of 50% or greater, and preferably of 75% or greater. In the present exemplary embodiment, a length of each of the radiating direction extension portions 14a in directions radiating out from the opening 1 lb (sometimes referred to below simply as the length of the radiating direction extension portions 14a) is preferably longer than a length of each of the rear face plate-joining portions 21b. A thickness of each of the radiating direction extension portions 14a may be the same thickness as that of each of the rear face plate-joining portions 21b, or may be different therefrom. [0037] In the present exemplary embodiment, as illustrated in Fig. 1D to Fig. iF, the length of each of the radiating direction extension portions 14a is longer than the length of the respective rear face plate-joining portion 21b to which the radiating direction extension portions 14a faces . The leading end side in the radiating direction of each of the radiating direction extension portions 14a extends further to an outer peripheral side of the rear face 11 7628383_1 (GHMatters) P99901.AU plate 11 than each of the rear face plate-joining portions 21b. Adopting such a configuration means that stress imparted from each of the rear face plate-joining portions 21b to the rear face plate 11 is dissipated over a wider range by each of the radiating direction extension portions 14a. In such cases, the length of each of the radiating direction extension portions 14a is 0.5 to 5.0 times the length of the respective facing rear face plate-joining portions 21b, and is preferably 1.0 to 3.0 times, and more preferably 2.0 to 3.0 times. Each of the radiating direction extension portions 14a may extend further to the outer peripheral side of the rear face plate 11 than the mounting portion coupling region 11 a (and as far as the side face plates 13 at the longest). In the present exemplary embodiment, as illustrated in Fig. iF, the thickness of each of the radiating direction extension portions 14a is the same as the thickness of each of the rear face plate-joining portions 21b. Accordingly, in the projection plane, the rear end cross-sections of the respective radiating direction extension portions 14a overlap with all the front end cross-section of the respective rear face plate-joining portions 21b. Thus in the present exemplary embodiment, in a projection image of the rear end cross-section of each of the radiating direction extension portions 14a and the front end cross-section of each of the rear face plate-joining portions 21b projected onto the projection plane, lines other than the outline of each of the radiating direction extension portions 14a essentially disappear from Fig. 1D. [0038] As illustrated in Fig. 1B, 1D, in the present exemplary embodiment, further to the outer peripheral side of the rear face plate 11 than the mounting portion coupling region 11 a (a mount non-coupled region), the coupling piece 14 is configured by plural longitudinal direction extension portions 14b that extend along the rear face plate 11 and the front face plate 12 in one direction (referred to below, for convenience, as the longitudinal direction), and plural transverse direction extension portions 14c that extend along the rear face plate 11 and the front face plate 12 in a direction orthogonal to the longitudinal direction extension portions 14b (referred to below, for convenience, as the transverse direction). The longitudinal direction extension portions 14b and the transverse direction extension portions 14c are disposed so as to intersect with each other in a lattice pattern, and are joined to each other by a joining means, such as welding. The angle of intersection between the longitudinal direction extension portions 14b and the transverse direction extension portions 14c is not limited to being a right angle. Coupling pieces may be further provided obliquely with respect to the longitudinal direction extension portions 14b and to the transverse direction extension portions 14c. [0039] The mounting portion coupling region 11a is surrounded by a pair of the longitudinal 12 7628383_1 (GHMatters) P99901.AU direction extension portions 14b and a pair of the transverse direction extension portions 14c. The radiating direction leading end side of each of the radiating direction extension portions 14a is joined to either one of the longitudinal direction extension portions 14b or one of the transverse direction extension portions 14c by a joining means, such as welding. [0040] The coupling piece 14 may be present inside the mounting portion coupling region 11a at locations where the front of the rear face plate-joining portions 21b of the mounting portion 20 are not opposed via the rear face plate 11. For example, in the present exemplary embodiment, there are longitudinal direction extension portions 14b arranged between some of the radiating direction extension portions 14a, 14a in order to reinforce the mounting portion coupling region 11a. Leading end coupling pieces 14d are arranged at locations between radiating direction extension portions 14a, 14a that are mutually adjacent, but do not have their respective radiating direction leading end sides joined to either a common longitudinal direction extension portion 14b or a common transverse direction extension portion 14c, so as to couple together the respective leading end portions of the radiating direction extension portions 14a, 14a. However, the layout of the coupling piece 14 is not limited thereto. [0041] The cushion member 10 and the mounting portion 20 are each configured overall from rigid material, such as steel. Specific materials for the cushion member 10 and the mounting portion 20, and dimensions of each portion thereof, such as the thickness, are appropriately set according to the maximum permissible value of load to be applied to the cushion member 10, and the like. [0042] In the fender 1 having the thus configured cushion member 10 installed to the front face portion of the fender main body 2, when a berthing object, such as a ship, comes alongside and contacts the cushion member 10, the fender main body 2 deforms under the load from the object coming alongside, so as to collapse along the axial center line direction while an axial center line direction intermediate portion widens in diameter, absorbing the impact. When this occurs, due to the mounting portion 20 sinking in toward the inside of the fender main body 2 accompanying the cushion member 10 moving toward the rear, the deformation amount of the fender main body 2 is larger than cases in which a cushion member is directly attached to the fender main body. This thereby enables the fender 1 to exhibit higher impact absorbing performance. [0043] For the cushion member 10, in the projection plane, the surface area of the portion of the rear end cross-sections of the respective radiating direction extension portions 14a that overlap with the front end cross-sections of the respective rear face plate-joining portions 21b 13 7628383_1 (GHMatters) P99901.AU is 25% of the overall cross-sectional area of the front end cross-sections of the rear face plate-joining portions 21b, or greater (and the rear end cross-sections of the respective radiating direction extension portions 14a particularly preferably overlap with substantially all the front end cross-sections of the rear face plate-joining portions 21b). This thereby enables stress, imparted from the rear face plate-joining portions 2 lb to the rear face plate 11 when the cushion member 10 bears load from the front, to be efficiently distributed by each of the radiating direction extension portions 14a. This thereby enables the required strength of each of the portions of the cushion member 10 to be set comparatively low. As a result, both a reduction in weight of the cushion member 10, and a reduction in material cost of the cushion member 10, are achievable. [0044] In the present exemplary embodiment, each of the rear face plate-joining portions 21b of the mounting portion 20 and each of the radiating direction extension portions 14a of the coupling pieces 14 respectively extend along the rear face plate 11 so as to radiate out from the shaft shaped portion 21a. Thus the stress, imparted from the rear face plate-joining portions 21b to the rear face plate 11 when the cushion member 10 bears load from the front, is distributed over a wide range in a shape radiating out along the rear face plate-joining portions 21b and the radiating direction extension portions 14a, enabling the stress imparted to the rear face plate 11 to be even more efficiently distributed. [0045] The above exemplary embodiment is merely an example of the present invention, and the present invention may have a configuration different from that illustrated in the drawings. For example, for the pedestal 21 of the mounting portion 20, a configuration may be adopted in which the shaft shaped portion 21a is omitted, and each of the rear face plate-joining portions 21b extend along the rear face of the rear face plate 11 in a radial shape from the axial center position of the fender main body 2. [0046] In the above exemplary embodiment, all of the rear face plate-joining portions 21b extend along the rear face of the rear face plate 11 in directions radiating out from the shaft shaped portion 21a, however they may extend in directions other than the radiating directions. Moreover, in the above exemplary embodiment, all of the rear face plate-joining portions 21b extend in a straight line along the rear face of the rear face plate 11, however they may extend in other shapes than a straight line, such as an L-shape, a T-shape, a Y-shape, an X-shape, a zig-zag shape, or a circular arc shape. For example, configuration may be made such that at least some of the rear face plate-joining portions 21b extend in a circular arc shape along the circumferential direction of the shaft shaped portion 21a. [0047] In the present exemplary embodiment, the front end side of the shaft shaped portion 14 7628383_1 (GHMatters) P99901.AU 21a is disposed inside the cushion member 10. However, instead of the front end side of the shaft shaped portion 21a being disposed inside the cushion member 10, a coupling piece that is of substantially circular cylindrical shape and has the same diameter as the shaft shaped portion 21a may be arranged coaxially to the shaft shaped portion 21a inside the cushion member 10. [0048] In the present exemplary embodiment, the shaft shaped portion 21a has a circular shaped cross-section, however the cross-section shape of the shaft shaped portion 21a is not limited thereto. The shaft shaped portion 21a may, for example, have an elliptical shaped cross-section, or may have a polygonal shaped cross-section. Moreover, in the above exemplary embodiment, the shaft shaped portion 21a has a cylindrical shape that is hollow inside, however a solid bar shape may be employed having no hollow inside. [0049] Two of more of the mounting portions 20 may be provided to the rear face of the rear face plate 11. Examples [0050] Comparative Example In a fender 1A according to a Comparative Example of Fig. 2A to Fig. 2C, a coupling piece 14A disposed inside a cushion member 10A is configured similarly to in JP-A No. H11-43921, with an overall configuration including only plural longitudinal direction extension portions 14b and transverse direction extension portions 14c that intersect with each other in a lattice pattern. [0051] In a mounting portion 20A coupling the cushion member 10A to the fender main body 2, a front end face of a shaft shaped portion 21a' of a pedestal 21A is in the same plane as a front end face of each of the rear face plate-joining portions 21b. A front end side of the shaft shaped portion 21a' is not disposed inside the cushion member 10A, and abuts a rear face of the rear face plate 11 and is joined to the rear face plate 11 by a joining means, such as welding. [0052] Other configuration of the fender 1A is similar to that of the fender 1 according to the exemplary embodiment, and in Fig. 2A to Fig. 2C, the same reference numerals as those of Fig. 1A to Fig. iF denote similar portions. [0053] In the fender 1A, as illustrated in Fig. 2B, in a mounting portion coupling region 11a of the rear face plate 11, the longitudinal direction extension portions 14b and the transverse direction extension portions 14c are also disposed extending in two orthogonal directions. The longitudinal direction extension portions 14b and the transverse direction extension portions 14c do not face toward all of the rear face plate-joining portions 21b of the mounting 15 7628383_1 (GHMatters) P99901.AU portion 20A, and instead there are locally facing portions that cut across in front of the rear face plate-joining portions 21b. In the thus configured fender 1A, in a projection plane, when rear end cross-sections of the coupling pieces 14 (the longitudinal direction extension portions 14b and the transverse direction extension portions 14c), and a front end cross-section of each of the rear face plate-joining portions 21b are projected onto a common projection plane substantially orthogonal to the axial center line of the fender main body 2, a surface area of a portion of the rear end cross-sections of the coupling pieces 14 overlapping with the front end cross-section of each of the rear face plate-joining portions 21b is less than 25% of the total surface area of each of the front end cross-section of the rear face plate-joining portions 21b. [0054] Load Bearing Test Distributions of stress applied to the rear face plates 11 from each of the rear face plate-joining portions 21b of the mounting portions 20, 20A when the cushion member 10 of the fender 1 according to the present exemplary embodiment, or the cushion member 10A of the fender 1A of the Comparative Example, were each imparted with load from the front under the same conditions, were analyzed using FEM (program used: general purpose structural analysis program Marc Mentat from MSC; number of elements: 16000 for the cushion member (the front face plate + the rear face plate + the coupling piece + the mounting portion), 4000 for the fender main body, element type: 8 node solid elements). [0055] Respective measurement results are illustrated in Fig. 3A and Fig. 3B. [0056] Observations As illustrated in Fig. 3A, in the fender 1 according to the exemplary embodiment, the region of peak stress imparted to the rear face plate 11 spans a wide range along the radiating direction extension portions 14a. It is accordingly apparent that stress is efficiently distributed by the radiating direction extension portions 14a. [0057] In contrast thereto, as illustrated in Fig. 3B, it is apparent that in the fender 1A according to the Comparative Example, the region of peak stress imparted to the rear face plate 11 is concentrated at the points of intersection of the rear face plate-joining portions 2 lb with either the longitudinal direction extension portions 14b and the transverse direction extension portions 14c. There is accordingly a need in the fender 1A according to the Comparative Example for a high strength rear face plate 11 in order to sufficiently withstand such concentrations of stress, thereby increasing the weight and material cost. [0058] The entire content disclosed in Japanese Patent Application 2012-245180 is incorporated by reference herein. All publications, patent applications and technical 16 7628383_1 (GHMatters) P99901.AU standards mentioned in the present specification are incorporated by reference in the present specification to the same extent as if the individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference. [0059] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 17 7628383_1 (GHMatters) P99901.AU