GB2111942A - Improvements in or relating to a marine derrick - Google Patents

Abstract

A marine derrick 10 comprises a boom of jib 1 having one end thereof turnably mounted on a derrick post 2 by means of a goose neck fitting 18 so that the free end of the boom may move vertically and horizontally relative to the derrick post, said derrick including a topping and guy system comprising two separate lengths 3,3' of continuous wire, each disposed substantially symmetrically on opposite sides of the derrick post, both of said continuous wires each having a respective end connected to and extending out from one side of a topping winch 5 so that, on operation of the winch, both wires are reeled in or paid out simultaneously, each wire 3,3' then passing through a respective sheave 7,7' adjacent the top of the derrick post and through a respective sheave 8,8' adjacent the free end of the boom to form a topping lift system, each wire 3,3' then passing downwardly, through a respective further sheave 9,9', said further sheaves being mounted on either side of the derrick post 2, and then to a guy winch 6 adapted to draw one wire 3 or 3' in whilst simultaneously paying the other wire 3' or 3 out to form a slewing guy system. <IMAGE>

Description

SPECIFICATION Improvements in or relating to a marine derrick The present invention relates to a marine derrick.

Various marine derricks have been proposed. Some prior proposed marine derricks utilise a double topping wire system, and examples of such prior proposed derricks are shown in Figs. 7, 8 and 9 of the accompanying drawings which respectively illustrate marine derricks known as the Maeno type, the Thompson type and the Velle type. Marine derricks of this type require a vertical mast having an outrigger at the top which has a very wide span. There are two topping wires which extend upwardly from the end of the outrigger to the uppermost ends of the boom, the topping wires thus extending upwardly but having a relatively wide working angle.

The topping wires can thus act not only to lift the boom upwardly, but also to pivot the boom from side to side. Occasionally guy wires are additionally provided.

The main disadvantage of systems of this type is that, since there is no wire portion to provide a downward force on the boom, the boom is not maintained in a steady position, and it is relatively easy for the boom to drift out of control while the boom is swung outboard, especially when the boom is at a position close to the end of its maximum possible swing. Also, of course, the necessary mast with a wide outrigger, which in some cases is replaced by a portal arrangement as shown in Fig. 8, does not improve the stability of the ship, and also tends to obscure visibility. Also, the structural costs are significant.

A further type of conventional marine derrick utilises the single topping wire system, or slewing guy system. Examples of such derricks are shown in Figs. 10, 11 and 12, these derricks all being known as derricks of the K-7 type, since these derricks all include a single independent topping wire extending from the free end of the boom to the top of the mast, and two generally downwardly extending guy wires. The main disadvantage of this system is that the guy wires will always be slack on one side or other, and thus need to have some means capable of absorbing the slack in the wires. Usually this is achieved by connecting the guy wire ends to the toppping lift wire portion either at the free end of the boom, or at some other position. However, this tends to make the wires whip, and can thus lead to injuries.Also, if the single topping wire breaks for any reason the boom will fall down immediately, which can result in a severe accident.

Consequently this system is regarded as being very unsafe.

The present invention seeks to provide a marine derrick in which the disadvantages of the above described derricks are reduced or obviated.

According to this invention there is provided a marine derrick comprising a boom or jib having one end thereof turnably mounted on a derrick post by means of a goose neck fitting so that the free end of the boom may move vertically and horizontally relative to the derrick post, said derrick including a topping and guy system comprising two separate lengths of continuous wire, each disposed substantially symmetrically on opposite sides of the derrick post, both of said continuous wires each having a respective end connected to and extending out from one side of a topping winch so that, on operation of the winch, both wires are reeled in or paid out simultaneously, each wire then passing through a respective sheave adjacent the top of the derrick post and through a respective sheave adjacent the free end of the boom to form a topping lift system, each wire then passing downwardly, through a respective further sheave, said further sheaves being mounted on either side of the derrick post, and then to a guy winch adapted to reel one wire in whilst simultaneously paying the other wire out to form a slewing guy system. Preferably each wire passes through a second sheave adjacent the top of the derrick post when passing from the free end of the boom to the respective said further sheave which is located to one side of the derrick post. Conveniently each wire, after leaving said further sheave, passes through another sheave which is mounted on or adjacent the free end of the boom and yet another sheave which is mounted adjacent the said further sheave located to one side of the derrick post before passing to said guy winch.Advantageously the sheaves provided at the top of the derrick post are provided at the ends of a cross piece provided at the top of the derrick post.

In one embodiment each wire passes through yet a further sheave which is mounted on or adjacent the free end of the boom after passing from said second sheave adjacent the top of the derrick post and the respective said further sheave mounted to one side of the derrick post. Preferably said goose neck comprises a universal joint having both vertical and horizontal pins. Conveniently a platform is provided on the derrick post at a predetermined level above the decks supporting the topping winch and guy winch with the goose neck fitting being located at substantially the same level as that of the platform so as to form a concentrated cargo handling unit elevated from the deck. Said sheaves at either side of the derrick post may be located at said level.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the inven tion will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view showing one embodiment of a marine derrick in accordance with the present invention, arranged on a winch platform; Figure 2 is a plan view of the derrick of Fig.

1, showing the basic wiring diagram; Figure 3 is a perspective view showing a modification of the derrick boom shown in Fig. 1; Figure 4 is a perspective view showing a variation of the invention with a heavier wire rigging, again arranged on a winched platform; Figure 5 is a plan view, corresponding to Fig. 2, showing the basis wire diagram of the embodiment illustrated in Fig.4; Figure 6 is a perspective view showing a further modified of the invention; Figures 7, 8 and 9 are perspective views showing various types of conventional marine derrick utilising a double topping system; and Figures 10, ii and 12 are perspective views showing conventional marine derricks having a single topping system, or so called slewing guy system.

Referring to Figs. 1 and 2, a marine derrick 10 in accordance with the present invention comprises a derrick post 2 which extends upwardly from the deck, and which is provided, at the top, with a short cross member 4. A derrick boom 1 is turnably mounted on the derrick post 2 adjacent its narrow end by means of a goose neck fitting 1 8. The goose neck fitting 1 8 is, effectively, a universal joint, since the goose neck fitting includes both horizontal and vertical pivotally mounted pins.

The free end of the boom 1 is movable horizontally and vertically relative to the derrick post 2. The marine derrick 10 additionally includes a co-axial drum type topping winch 5, which can be utilised to raise and lower the boom, and a co-axial dual drum type guy winch 6, which can be utilised to slew the boom 1 from side to side. Both the drums of the topping winch 5 will always rotate in the same direction and at the same speed at each other. Similarly both the drums of the guy winch 6 will rotate in the same direction and at the same speed as each other. The winches are mounted on a winch platform at or near deck level at the foot of the derrick post 2.

A pair of guy posts 11, 11' are provided, the guy posts being located on opposite sides of the derrick post 2. Conveniently the guy posts 11 and 11' may each be located adjacent a respective side of the ship. The tops of the guy posts are at the same level as the goose neck.

Two blocks, namely a first block 7 and a second block 9 are provided at one end of the cross member 4 which is mounted on top of the derrick post 2, for example the end of the cross member that is located on the starboard side of the ship. A second pair of blocks comprising a first block 1 2 and a second block 1 5 are provided on top of the guy post 11 that is closest to said one end of the cross member 4, and thus the guy post 11 may be considered to be mounted on the starboard side of the ship. A block 8 is mounted on the derrick boom 1 adjacent the top end thereof, the block being located, in this case, to one side of the boom, namely the starboard side.

A similar arrangement of blocks is provided at the port end of the cross member, on a port side guy post 1 1', and at the free end of the boom, and this set of blocks are illustrated with the same reference numbers as those utilised above accompanied by a prime (').

A single length of integrally continuous wire 3 has one end wound around one drum of the topping winch 5, and the wire extends from that one drum upwardly through the first block 7 on top of the derrick post, then through the block 8 on top of the boom 1, and subsequently through the second block 9 on top of the derrick post 2. Subsequently the wire passes sideways and downwards towards the guy post 11, and is entrained about the first block 1 2 on the guy post. The wire then passes through a block 1 3 which is suspended from the top of the boom 1 by means of a strap (guy pendant) 14, then through the second block 1 5 on top of the guy post 11 and then is led to one drum of the dual type guy winch 6 on the starboard side.A second wire 3' is wired in a very similar manner on the other side of the derrick, one end of the wire being connected to the second drum of the topping winch 5, and the other end of the wire being connected to the guy winch 6 after having been entrained about the first block 7' on top of the derrick post 2, a block 8' on top of the boom 1, the second block 9' on top of the derrick post 2, the first block 12' on top of the guy post 1 1', a block 1 3' suspended from the top end of boom 1 by means of a strap (guide pendant) 14', and the second block 15' on top of the guide post 1 1', so as to form a mirror image of the wire 3 described hereinabove.

It is to be noted that the ends of wires 3, 3' connected to the topping winch 5 are both connected to the same sides of the respective drums, so that, when the winch operates in one direction both the wires are reeled in, and when the winch operates in the other direction both the wires are paid out. Thus, on operation of the winch 5 it is possible to raise or lower the boom 1. However, it is to be noted that the ends of the wires 3, 3' connected to the guy winch 6 are connected to opposite sides of the drums so that, as the winch operates in one direction one wire is reeled in, and the other wire is paid out.

When the direction of operation of the winch is reversed the one wire is paid out and the other wire is reeled in. Thus, by operating the guy winch 6 the boom may be swung from side to side.

Fig. 3 shows a further embodiment of a marine derrick in accordance with the invention which can be considered to be a modification of the derrick 10 shown in Fig. 1. In Fig. 3 the various components of the derrick that correspond with the components shown in Figs. 1 and 2 are provided with the same reference numerals. However, it is to be noted that the marine derrick of Fig. 3 is provided with a spacing head 1 9 at the end of the boom provided with cargo lifting pullies and with an engine casing 20 mounted on the derrick post, substantially at the level of the goose neck 18, so as to form a more compact and concentrated boom or jib handling unit element which is elevated from the deck. A control station 21, in the form of a cabin for an operator, is provided on the derrick post 2.

The winches, including the topping winch and the guy winch, can be at any suitable location, and not necessarily as shown in the Figure.

Figs. 4 and 5 illustrate yet another embodiment of the invention which can be considered to be a modification of the derrick shown in Fig. 1, and again the same reference numerals are used for like components wherever practicable. This embodiment differs from the embodiment shown in Fig. 1 in that the portion of the wire 3 extending between the second block 9 on top of the derrick post 2 and the first block 1 2 on top of the guy post 11 is pulled, at the mid point thereof, towards the top end of the boom 1 and is entrained about an additional block 1 7 which is mounted on the boom 1 adjacent the top end thereof, as shown in Fig. 4. The block 1 7 may, if desired, be mounted to the top of the boom by means of a strap (guy pendant).Of course, a portion of the wire 3' extending between the second block 9' on top of the derrick post 2 and the first block 12' on top of the guide post 11' is also pulled towards the top end of the boom 1 and is entrained about a block 17' which is also mounted on the boom 1. The provision of the additional blocks 17, 17', facilitate the slewing action of the boom without the top of the boom rising to falling.

Fig. 6 shows a further embodiment of the invention which can be considered to be a modification of the embodiment shown in Fig.

4, incorporating features described in Fig. 3, and in this embodiment an engine casing 20 is provided on the derrick post 2 at the level of the goose neck 1 8 so as to form a compact and concentrated boom handling unit elevated from the deck. Again a control station 21, in the form of a cabin for an operator, is provided or the derrick post.

It is to be appreciated that in all the above described embodiments cargo hoist winch and wire is provided, as is conventional in such derricks. These winches and wires have not been described in detail, for the sake of simplicity.

In operation of the derrick as illustrated in Fig. 1 the derrick boom can be moved upwardly and downwardly ("topped") by winding up or paying up both the control wires 3 and 3' simultaneously in the same direction and in the same amount by actuating the topping winch 5. As has been described above, both the wires are connected to the drums of the winch in the same direction. The derrick boom may be swung either to the starboard side or to the port side by actuating the guy winch 6 in the appropriate direction, since both the wires are connected to the respective drums in opposite directions, and thus when the winch is actuated one wire is reeled in and the other wire is paid out.No slackness of any guy wire portion will occur, as any slackness will be absorbed by the topping wire portion which is always tight as a result of the weight of the boom (and any cargo) that is always applied to this wire.

The wiring arrangements described above can be reinforced by utilising an increased number of wires if necessary. Where reference has been made above to two blocks being located at the same position it is to be appreciated that a double sheave block may be utilised to have the same effect.

Embodiments of the present invention may be considered to be derricks utilising a double topping guy system, since the derricks have a dual topping and guy system. When embodiments of the present invention are compared with derricks which use the conventional double topping system it is to be noted that the present invention does not require the provision of a huge heavy and wide span outrigger at the top of the derrick post. Thus, by utilising the present invention it is possible to improve the stability of the ship, and also to improve the visibility from the ship. Also, since the preferred derricks in accordance with the invention have downwardly extending guide wires which are rigged, for example, to the utmost span of the ships side, it is possible with such embodiments, to obtain a very steady derrick boom motion, even if the boom is swung outboard to a position near abeam.

When embodiments of the present invention are compared with conventional single topping system derricks it is to be noted that, since each of the control wires 3 and 3', as described above, is an integral wire having one part working at the topping lift and another part working as a guy wire, any slackness produced in the part working as a guy wire will be readily absorbed by the part working as a topping lift, thereby enabling each wire to be maintained taught without any connector fittings between the topping system and the guy system. This enables the derrick boom to be kept under control steadily at all times so as to enhance the safety of the derrick. The dual type control wires 3, 3', will also help to enhance the safety level, since even if one wire breaks, the other wire may remain intact, thus preventing the cargo or boom from falling.

It is envisaged that preferred embodiments of the invention will comprise marine derricks which are capable of improving the stability of ships, and also improving the efficiency of boom handling, by the incorporation of dual control wires of the derrick boom or jib which each work as combined topping lift and guy wire.

Claims (14)

1. A marine derrick comprising a boom or jib having one end thereof turnably mounted on a derrick post by means of a goose neck fitting so that the free end of the boom may move vertically and horizontally relative to the derrick post, said derrick including a topping and guy system comprising two separate lengths of continuous wire, each disposed substantially symmetrically on opposite sides of the derrick post, both of said continuous wires each having a respective end connected to and extending out from one side of a topping winch so that, on operation of the winch, both wires are reeled in or paid out simultaneously, each wire then passing through a respective sheave adjacent the top of the derrick post and through a respective sheave adjacent the free end of the boom to form a topping lift system, each wire then passing downwardly, through a respective further sheave, said further sheaves being mounted on either side of the derrick post, and then to a guy winch adapted to reel one wire in whilst simultaneously paying the other wire out to form a slewing guy system.

2. A marine derrick according to claim 1 wherein each wire passes through a second sheave adjacent the top of the derrick post when passing from the free end of the boom to the respective said further sheave which is located to one side of the derrick post.

3. A derrick according to claim 1 or 2, wherein each wire, after leaving said further sheave, passes through another sheave which is mounted on or adjacent the free end of the boom and yet another sheave which is mounted adjacent the said further sheave located to one side of the derrick post before passing to said guy winch.

4. A marine derrick according to any one of the preceding claims wherein the sheaves provided at the top of the derrick post are provided at the ends of a cross piece provided at the top of the derrick post.

5. A derrick according to any one of the preceding claims wherein the said further sheaves provided at either side of the derrick post are provided on guy posts.

6. A derrick according to claim 2 or any claim dependent thereon wherein each wire passes through yet a further sheave which is mounted on or adjacent the free end of the boom after passing from said second sheave adjacent the top of the derrick post and the respective said further sheave mounted to one side of the derrick post.

7. A marine derrick according to any one of the preceding claims wherein said goose neck comprises a universal joint having both vertical and horizontal pins.

8. A marine derrick according to any one of the preceding claims wherein a platform is provided on the derrick post at a predetermined level above the decks supporting the topping winch and guy winch with the goose neck fitting being located at substantially the same level as that of the platform so as to form a concentrated cargo handling unit elevated from the deck.

9. A marine derrick according to claim 8 wherein said sheaves at either side of the derrick post are located at said level.

10. A marine derrick substantially as herein described with reference to and as shown in Figs. 1 and 2.

11. A marine derrick substantially as herein described with reference to and as shown in Fig. 3.

1 2. A marine derrick substantially as herein described with reference to and as shown in Figs. 4 and 5.

1 3. A marine derrick substantially as herein described with reference to and as shown in Fig. 6.

14. Any novel feature or combination of features shown herein.