Ladder fenders, which integrate the functions of a ladder and fender in a single unit. are typically used in quayside applications. In such applications the ladder fender is mounted vertically to extend down the vertical face of a quayside to provide for personnel access and to serve as an impact absorbing fender for vessels approaching the quayside or moored there.

In known ladder fenders steel components of the ladder are moulded into the rubber of the fender. This type of construction has been found to be unsatisfactory because vessel-applied impacts on the ladder fender and consequent bending and flexing thereof can cause premature ladder and/or fender failure.

The present invention seeks to provide an alternative ladder fender.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a ladder fender comprising a ladder having one or more stringers and rungs transverse to the stringer (s), and at least one hollow, tubular fender structure which is made of resilient material and which is penetrated transversely by the rungs of the ladder with no rigid connection between the fender structure and the ladder, whereby the fender structure is capable of at least limited resilient deformation relative to the ladder.

In one embodiment of the invention, there is a pair of parallel stringers each extending longitudinally through a fender structure, the rungs extending between the stringers through transverse openings in the fender structures.

In another embodiment of the invention, there is a pair of stringers located on opposite sides of a fender structure, the rungs extending transversely through the fender structure between the stringers. In a third embodiment of the invention, there is a single stringer extending longitudinally through a fender structure, the rungs having respective portions which penetrate the fender structure and extend to opposite sides of the stringer.

In each embodiment, each fender structure preferably comprises a plurality of hollow cylindrical fender elements arranged coaxially in end to end relationship. Conveniently, the fender elements are held in coaxial alignment by means of resilient alignment elements each locating partially in one fender element and partially in an adjacent fender element.

Typically each stringer is threaded through openings in the rungs and has a suspension formation, possibly in the form of an eye, at an operatively upper end thereof by means of which it can be suspended from a supporting structure on a quay so as to hang vertically adjacent the quayside.

Tread portions of the rungs which are located outside the fender structures are preferably coated with rubber to provide a non-slip characteristic. According to another aspect of the invention there is provided a quayside ladder fender installation comprising a ladder fender as summarised above and a fixed supporting structure extending laterally over the quayside, the stringer (s) of the ladder fender being suspended from the supporting structure with fender structure (s) lying adjacent an upright wall of the quayside, the suspension of the ladder fender from the supporting structure being such as to allow at least limited swinging movement of the ladder fender relative to the supporting structure.

According to yet another aspect of the invention there is provided a ladder fender comprising a ladder and a resilient, hollow tubular fender structure, the ladder including at least one stringer relative to which a plurality of rungs extend transversely and which extends axially and with clearance in the hollow of the fender structure.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which : Figure 1 shows a partly sectioned side view of a ladder fender according to this invention; Figure 2 diagrammatically illustrates how the ladder fender of Figure 1 is suspended in use; and Figure 3 shows a partly sectioned side view of another ladder fender according to this invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS The ladder fender 10 seen in Figure 1 has an elongate ladder including a pair of parallel stringers 12 with a series of spaced rungs 14 extending transversely between the stringers, and a pair of fender structures 16.

The stringers 12 are slender stainless steel bars and are fitted with eyes 18 at their upper ends. The rungs are stainless steel tubes formed with vertical openings 20 towards their opposite ends through which the stringers 12 are threaded. Each rung is also formed with further vertical openings 22, adjacent the openings 20, to take vertical locating pins 24 as described below.

Each fender structure 16 is composed of fender elements 26. Each fender element 26 is a hollow tubular member made of a resilient material such as rubber. The elements 26 are arranged end to end to form the illustrated, elongate, hollow, tubular fender structure. They are maintained in coaxial alignment by hollow cylindrical alignment elements 28 fitting snugly in the ends of the fender elements and locating partially in one element and partially in the next.

Each fender element 26 is formed with two diametrically extending openings 30 which intersect the central bore thereof. The ends of the rungs 14 penetrate the fender elements through these openings and extend into the central hollows of the fender elements. The stringers 12 pass vertically through the fender structures and are threaded through the openings 20.

The lower ends of the stringers are threaded to take nuts 32 beneath the lowest rung 14.

Between the fender structures 16 the tread portions 34 of the rungs are encased in rubber to provide a non-slip characteristic.

There is no bond between the fender structures and the ladder, so that the fender structures are not rigidly connected to the ladder. The stringers 12 of the ladder pass loosely, with clearance, through the fender elements 26 and the alignment elements 28 and the rungs 14 of the ladder likewise pass loosely through the openings 30. The ends of the rungs are located with respect to the fender elements by means of the vertical locating pins 24 which, as mentioned previously, are inserted in the openings 22. In the absence of a bond or other rigid connection between the steel ladder components and the rubber or rubber-based fender structures, it will be understood that the fender structures are capable of deforming relative to the ladder and without transferring the applied loading and deformation to the ladder.

In use, the ladder fender 10 is suspended vertically at a quayside. This is illustrated in Figure 2 in which the numeral 36 indicates the vertical quayside wall and the numeral 38 the horizontal quay surface. An arched han-rail 40 is secured to a structure 42, mounted on the surface 38, which has portions 44 projecting out over the quayside as illustrated. The eyes 18 of the stringers12 are located over hooks at the ends of the projecting portions 44 so that the ladder fender can hang vertically with the fender structures 16, at rest, lying against the quayside wall 36.

In Figure 3, which illustrates another embodiment 46 of the invention, components corresponding to those in Figure 1 are indicated with the same reference numerals. In this embodiment, which is suspended at the quayside in the same manner as the ladder of Figure 1, there is a single fender structure 16 located centrally between the stringers 12. The rungs 14 extend diametrically through the fender elements 26 of the fender structure and are located with respect thereto by pairs of locating pins 24 inserted in vertical openings in the rungs, within the fender structure, as illustrated. The outer tread portions 34 of the rungs are rubber coated to reduce slippage.

It will be appreciated that the fender structure (s) 16 have a considerably greater transverse dimension, in a direction normal to the quayside wall 36, than the ladder itself. As a result, the fender structures are able to serve a normal fender function to absorb impacts from vessels approaching or moored at the quayside, thereby protecting the quayside and ladder as well as the vessel itself from damage.

When compared to conventional ladder fenders the illustrated embodiments have the important advantage that resilient components of the fender structure (s) and the rigid components of the ladder are not firmly connected to one another, thereby allowing the relative deformation mentioned above to take place. Thus if the fender structure 16 of either embodiment is impacted by a vessel the resilient components can deform to absorb the impact forces without transferring undue loading and possible deformation to the rigid ladder components. It is accordingly envisaged that ladder fenders of the invention will be less prone to failure than currently known ladder fenders.

It will also be understood that, should damage occur, individual fender elements 26, stringers 12 and/or rungs 14 can be replace without undue difficulty.

A further advantage of the illustrated embodiments arises from the manner in which they are suspended at the quayside, allowing them to swing relatively freely if impacted upon. This is in contrast to conventional ladder fenders which are rigidly bolted or otherwise fixed to the vertical quayside wall.

In another embodiment of the invention, not illustrated, there is a single stringer passing vertically through a single fender structure similar to those described above, with a series of rungs through which the stringer is threaded centrally. The rungs penetrate diametrically through the fender structure with free, outer ends of the rungs on either side of the fender structure serving as treads. As in the previous embodiments, there is no bond between the fender structure and stringers and rungs of the ladder. This embodiment is however less preferred since the freely projecting ends of the rungs are exposed to potential impact damage. in each of the embodiments described above, the stringers 12 of the ladder are in the form of stainless steel rods or bars. It is however within the scope of the invention for these components to be provided by lengths of flexible, typicially stainless steel cable.