US3474749A

US3474749A - Floatable vessel

Info

Publication number: US3474749A
Application number: US709066A
Authority: US
Inventors: Robert Henry Williamson
Original assignee: Vickers Ltd
Current assignee: Vickers Ltd
Priority date: 1965-08-10
Filing date: 1968-02-28
Publication date: 1969-10-28
Anticipated expiration: 1986-10-28
Also published as: NL6804582A; GB1169262A; ES351391A2; FR94851E; NO122577B

Description

R. H. WILLIAMSON FLOATABLE vnssm, V

3 Sheets-Sheet '1' ,Eged Feb. 28, 1968 Oc't- 1959 g R. H. WILLIAMSON 3,47

FLOA'I'ABLE VESSEL Filed Feb. 28, 1968 3 Sheets-Sheet 2 United States Patent US. Cl. 114-5 4 Claims ABSTRACT OF THE DISCLOSURE The invention is concerned with a floatable vessel consisting of an upright column carrying a ballast chamber positioned adjacent the lower end of the column, a buoyant superstructure slidably mounted on the column for movement between a lower position adjacent the ballast chamber and an upper position adjacent the upper end of the column and means for securing the superstructure in the upper position. The invention provides a mooring arrangement consisting of a plurality of mooring lines connected to the vessel adjacent the lower end of the column and being arranged for attachment to anchorage points, the lines each extending over a support associated with the superstructure such that displacement of the latter along the column away from its lower end assists in tensioning the lines.

This invention relates to certain improvements in the floatable vessel forming the subject of co-pending patent application No. 569,617, now US. Patent No. 3,408,821, granted Nov. 5, 1968.

In the specification of the above application there is disclosed a floatable vessel including an upright column which carries a ballast chamber positioned at or near the lower end of the column, a buoyant superstructure which is slidably mounted On the column for movement between a lower position adjacent to the ballast chamber and an upper position at or near the upper end of the column and means for securing the superstructure in the upper position. Such a vessel will be referred to hereafter as a Floatable vessel as defined.

When considering the tensioning of say four mooring lines of a vessel, the mooring lines should be initially taut if a satisfactory mooring of the vessel is to be achieved. If the vessel is moored by first attaching two of the lines to the vessel and then bringing the third and fourth lines and the vessel together, the third and fourth lines require to be tensioned against their anchors and the vessel against the other two lines and their respective anchors which entails considerable difficulty.

According to the present invention, there is provided floatable vessel as defined, wherein the vessel is provided with a plurality of mooring lines connected to the vessel at or near the lower end of the column and being arranged for attachment to anchorage points, said lines each extending over a support associated with the superstructure, whereby displacement of the superstructure along the column away from its lower end assists in tensioning the lines.

In order that the invention may be fully understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 illustrates the vessel described in the above mentioned patent in the operational condition and provided with the mooring lines in accordance with the present invention attached to anchorage points,

FIGURE 2 illustrates a plan view of the vessel with the superstructure removed,

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FIGURE 3 illustrates a detail of the vessel shown in FIGURES 1 and 2,

FIGURE 4 illustrates a modification of the detail shown in FIGURE 3, and

FIGURES 5 to 8 illustrate the vessel at various stages in being converted from a towing condition to the operational condition before the latter condition is reached.

Referring to the drawings, the vessel itself is of the construction described with reference to the FIGURES 1 and 2 of the drawing accompanying the above mentioned patent and will not be described in detail herein. Broadly the vessel is composed of a column 1 provided with a ballast chamber 2 and carrying a buoyant superstructure 3. The vessel is provided with four mooring lines 4 each composed of a rope (not shown) and a chain cable 5 by means of which the rope is attached to the vessel. Each cable passes over a sprocket 6, and extends to a fixing point 7. Each sprocket '6 is mounted on a mooring ring 8 by means of a bracket '9, the sprocket itself being rotatable on a pin 11 (FIG. 3). The mooring ring encircles the column 1 and is connected to the superstructure 3 by two lifting cables 12.

To accommodate the brackets 9, sprockets 6 and cables 5 when the superstructure is positioned at the lower end of the column immediately above the ballast chamber 2, the latter is provided with four recesses 13 merging respectively with four further recesses 14.

In the towing condition of the vessel shown in FIG- URE 5, all four cables 5 are stowed in their respective recesses 13 in the ballast chamber 2. If the previously mentioned mooring ropes are already at the site attached to anchorage points on the sea bed, the ropes will be connected to the cables 5 on arrival at the site. It will be seen from FIGURE 5 that all the mooring lines at this stage are slack.

The reminder of the mooring procedure is as follows. The ballast chamber is first partly flooded and is allowed to sink to a position where the lifting cables 12 are fully extended to support the mooring ring 8 (FIGURE 6) and is further flooded slightly to cause the superstructure 3 to engage correctly with an associated collar 15 as described in the above mentioned patent, when the superstructure is locked to the collar (FIGURE 7).

Now the 'ballast chamber is flooded completely and allowed to sink to a depth where the superstructure reaches its operational position at the top of the column (FIGURE 8). This causes the mooring ring to be lifted up the column to a position approximately half way up the column whereat the ring is locked to the column and so also is the collar 15 locked to the column 1 as described in the above patent. At this stage the slack is taken out of the cable chains 5.

Finally the ballast chamber is unballasted slightly to allow the vessel to rise to the operating position (FIG- URE 1), this final upward movement applying a tension to the mooring lines 4.

If it is desired later to inspect the mooring attachments, the above procedure may be reversed.

The locking of the mooring ring to the central column is arranged so that should buoyancy in the column and ballast chamber be lost, the column can release from the ring in a similar manner to the arrangement for detaching the superstructure from the column as outlined in the above mentioned US. patent.

It will be seen that the above arrangement greatly facilitates the mooring of the vessel in that the securing of the mooring ropes to the cables can be carried out under slack mooring line conditions. The arrangement of the double purchase of the chains over approximately half the length of the vessel enables the mooring lines to be tensioned as a direct result of the conversion of the vessel from the towing to the operating condition.

The chain cables 5 may if desired be replaced by studlink cables 25 in which case the sprocket 6 would be replaced by toothed wheels 26, this being illustrated in FIGURE 4.

I claim:

1. A floatable waterborne vessel including an upright column carrying a ballast chamber adjacent its lower end and a buoyant superstructure mounted on the column for movement therealong between a lower position near the ballast chamber and an upper position adjacent the upper end of the column and means for securing the superstructure in its upper position, the ballast chamber being floodable to convert the vessel from a transit condition in which the ballast chamber floats in the water with the superstructure in its lower position, to an intermediate condition in which the ballast chamber is sunk in the water to draw the column downwardly through the superstructure as it floats in the water until the superstructure is at a position adjacent the upper end of the column and is secured thereto by the securing means, and said chamber being partially unballastable to elevate the superstructure clear of the water, wherein the improvement comprises a plurality of spaced mooring lines connected to the vessel at or near the lower end of the column and being arranged for attachment to anchorage points, a mooring line support associated with the superstructure and movable upwardly therewith, and each mooring line extending from its point of connection to the vessel over said support and to its anchorage point, whereby displacement of the lower end of the vessel and the superstructure away from each other takes up slack in the lines and assists in tensioning them.

2. A vessel as claimed in claim 1, wherein the support comprises a ring which encircles the column and is connected to the superstructure, said ring carrying, for each line, a rotatable support element over which the line passes.

3. A vessel as claimed in claim 2, wherein the rotatable support elements are each disposed on a pin which is mounted in a bracket depending from the ring.

4. A vessel as claimed in claim 1, wherein the ends of the mooring lines at the vessel are secured to attachment points at the base of the column.

References Cited UNITED STATES PATENTS 3,031,997 5/1962 Nesbitt 1l40.5 3,294,051 12/1966 Khelstovsky 1l40.5

TRYGVE M. BLIX, Primary Examiner US. Cl. X.R.