GB2151686A - Ship's accommodation ladder - Google Patents

Abstract

The ladder 1 is pivotally secured at its upper end 13 to a platform 12. The platform and ladder can be stowed together and lowered together to an access point 30 in the ship's side below the stowage position. The platform can be releasably secured at or adjacent to access point 30. The assembly may be supported upon a cradle 18 to which the ladder is pivotally secured. <IMAGE>

Description

SPECIFICATION Accommodation ladder The present invention is concerned with accommodation ladders for ships and is an accommodation ladder assembly particularly suitable for use in providing access'to a point at a level below that at which the assembly is stowed.

An accommodation ladder is a rigid stairway which may be mounted parallel to the side of a ship to allow access to and from a boat or quayside. The ladder is usually pivoted at its upper end to a platform which in operative positon extends from the ship's side and the inclination of the ladder to the horizontal is adjusted by raising or lowering the lower end of the ladder, for example by means of a rope running from a winch located at deck level.

We have described in our UK Patent Specification No. 1309096 an apparatus for lowering, hoisting and stowing an accommodation ladder in which all of these operations are achieved in a relatively simple and inexpensive manner by means of a single rope controlled by a single winch. In that specification we have described and illustrated a specific form of that apparatus which is designed to be used when the ladder is able to be stowed adjacent to the level from which the ladder leads down in use. In that form of our prior invention, the top platform may be permanently pivoted at the point at which it is to be used.

When the accommodation ladder is to afford access from a point in the ship's side lower than that at which the ladder is stowed, then the lowering of the ladder into its working position becomes more complicated, as both its upper and its lower end have to be raised and lowered. Conventionally, two independent winches have been employed, one for each end of the ladder. The platform has been stowed separately at its working level and it has been necessary first to lower the ladder to that level and then to couple it manually to the platform before subsequently setting the slope of the ladder by adjusting the level of its lower end.

It is an object of the present invention to provide an accommodation ladder assembly suitable for use below its stowage level which is simpler to operate and less expensive to construct than such prior art proposals.

According to the present invention, an accommodation ladder assembly comprises an accommodation ladder pivotally secured at its upper end to a platform, means to secure the platform and ladder together in a stowed position, means to lower the platform and ladder together to an access point in the ship's side below the stowage position and means to removably secure the platform at or adjacent to said access point.

It will be understood that it is a characteristic feature of our invention that the ladder and top platform are stowed together at a point away from the operating level and are together lowered to the operating position. Thus the difficult conventional operation of aligning the ladder and platform in situ (by a seaman standing on the platform) is avoided and is replaced by the simpler operation of securing the platform, already attached to the ladder in its operating position. It addition, difficulties arising from stowing the platform at its operating level are avoided. For example, it is no longer necessary to provide a mechanism for swinging the platform out from the side of the ship, nor to devise a way of stowing the platform without impeding the operation of an associated access door.

The platform and ladder are stowed together and this may conveniently be achieved by turning the assembly, in its fully raised position, into a vertical orientation against the side of the ship, or against a deck rail, or preferably into a suitable storage housing. If desired the stowed assembly may be contained in an enclosed housing which protects it from damage due to accidents or to the effects of the elements.

Conventional means may be used to lower the platform and ladder together from the stowage position to the access point at which they are to be used. Thus they may be lowered by means of ropes controlled by winches, for example separate ropes run by independent winches, one for each end of the assembly, or a single continuous rope controlled by a single winch by an arrangement similar to that described in our above-mentioned prior patent specification.

In a preferred form of our invention, the ladder assembly is supported upon a cradle, to one end of which the ladder is pivotally secured at a point on that side of the centre of gravity of the ladder remote from the platform. ltthen becomes possible to control the operation of the ladder assembly simply by lowering and raising the cradle in a generally horizontal position. When the cradle has been lowered to that level at which the platform may be secured to the access point, further lowering of the cradle allows the ladder to pivot about its point of attachment to the cradle until the ladder is at its desired operating angle.

An important advantage of adopting the cradle arrangement is that the lowering of the cradle, and with it the whole accommodation ladder assembly, may be achieved using a single double-drum winch, with a rope from each drum controlling one end of the cradle. Since the cradle is lowered in a generally horizontal position throughout, the ropes are run out at equal rates to an equal extent and the need for independent control of the ropes is avoided.

Means are provided for removably securing the platform at or adjacent to the point of access from the ship. Since the weight of the ladder assembly is taken by the rope or ropes, the platform-securing means does not need to be substantial. A simple such means comprises studs on the platform engaging slots associated with an access doorway, for example in brackets projecting from the side of the ship or in lugs projecting from the doorway.

Additional security may be obtained by providing retaining clips by means of which such studs may be held in place in such slots.

The invention will now be further described with reference to the accompanying drawings, in which: Fig. 1 illustrates in perspective view an accommodation ladder assembly according to the present invention, in stowed position; Fig. 2 corresponds to Fig. 1 but with the assembly swung out from its stowed position and partly lowered towards its working position; and Fig. 3 corresponds to Figs. 1 and 2 but with the assembly in its working position.

Referring to the drawings, an accommodation ladder 1 comprising ladder sides 2 and treads 3 is suspended by ropes 4 and 5 from davits 6 and 7 respectively. The davits are pivoted at their inboard ends at pivot points 8 and 9 respectively within a stowage recess 10 in the deck wall 11 and it is therefore possible to swing the whole ladder assembly into the recess 10 for stowage when not in use, that is into the position shown in Fig. 1.

A swivel top platform consisting of an upper section 12, hinged to the upper end of the ladder 1 at 13, and a lower section having bracing brackets 15 and connected to the upper section 12 by swivel pin 16, is stowed with the ladder in the recess 10.

When the ladder is to be used, it is swung out with the davits 8,9 from the stowage recess 10 until it is suspended horizontally below the davits in the position corresponding generally to that shown in Fig. 2 (but with the ladder up against the davits). As can be seen in Figs.2 and 3, the davits 8 and 9 are connected together by a strut assembly 17.

The ladder 1 is supported on a cradle 18, to which it is pivotally secured at 19, a point sufficiently far towards the lower end of the ladder for the centre of gravity of the ladder to lie over the cradle. The cradle 18 itself carries pulleys 20 and 21, over which runs the rope 4, and pulleys 22 and 23, over which runs rope 5. The ropes 4 and 5, whose outer ends are anchored at points 24 and 25 respectively, are controlled by drums 26 and 27 respectively on a double-drum winch 28 on the deck inboard of the housing 10.

Rotation of the winch drums in the direction indicated by the arrow allows the ropes 4 and 5 to wind out in the direction shown by the arrows associated therewith and in turn lowers the cradle 18 and the-Ladder assembly under the influence of gravity. The winching arrangement is such that the cradle 18 remains generally horizontal throughout the lowering.

When the lower platform section 14 reaches the level of the lower edge 29 of the shell doorway 30 from which access to the ladder is required, studs 31 on the platform section 14 (only one of which is visible in Figs. 1 and 2) engage corresponding slots in two lugs 32 and 33 which have been swung out from the doorway 30. The studs are secured in place by means of spring clips.

Further lowering of the cradle 18 allows the ladder 1 to tilt about the hinge 13 until the lower end of the ladder is at the appropriate level for access to a boat orquayside as desired. Atthis point, the angle of the ladder to the horizontal preferably does not exceed 55".

Handrails 34 for the ladder 1 itself are carried by the ladder in collapsed position (Figs. 1 and 2) and are erected for use by pivoting the handrail uprights about pivots 35. Rails 36 for the platform 12 are stowed elsewhere and are erected using sockets 37 on the platform.

Lifting and stowing of the ladder assembly is readily effected by reversing the above procedure, entailing reversing of the direction of running of the winch 28.

Claims (9)

1. An accommodation ladder assembly for a ship comprising an accommodation ladder pivotally secured at its upper end to a platform, means to secure the platform and ladder in a stowed position together, means to lower the platform and ladder together to an access point in the ship's side below the stowage position and means to removably secure the platform at or adjacent to said access point.

2. An accommodation ladder assembly as claimed in claim 1, wherein the platform and ladder are together turned into a vertical orientation for stowing.

3. An accommodation ladder assembly as claimed in claim 1 or claim 2, wherein the means to lower the platform and ladder together comprise independent winches, one for each end of the assembly.

4. An accommodation ladder assembly as claimed in claim t or claim 2, wherein the means to lower the platform and ladder together comprises apparatus as claimed in any of the claims of United Kingdom Patent No. 1309096.

5. An accommodation ladder assembly as claimed in claim 1 or claim 2, wherein the ladder assembly is supported upon a cradle, to one end of which the ladder is pivotally secured at a point on that side of the centre of gravity of the ladder remote from the platform, and the means to lower the platform and ladder together comprises means to lower the cradle.

6. An accommodation ladder assembly as claimed in claim 5, wherein the means to lower the cradle comprises a double-drum winch, with a rope from each drum controlling one end of the cradle.

7. An accommodation ladder assembly as claimed in any of the preceding claims, wherein the means to removably secure the platform at or adjacent to the access point comprises studs on the platform engaging slots associated with an access doorway.

8. An accommodation ladder assembly as claimed in claim 7, wherein the slots are in brackets projecting from the side of the ship or in lugs projecting from the doorway.

9. An accommodation ladder assembly for a ship, said assembly being substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.