GB2050955A - Buoys - Google Patents

Abstract

A buoy comprises doughnut- shaped inflatable floats (23) removably mounted on a mandrel (21) between a support plate (22) and a retaining collar (24). Various buoyancies can thus be obtained by adjusting the number of floats. The buoy may be used for marking underwater cables during laying. <IMAGE>

Description

SPECIFICATION Buoy This invention relates to buoys.

Buoys are used in various applications to mark submerged objects in water. Two such applications arise during underwater cable laying operations when firstly it is required to provide a a surface connection to the end of a submerged cable prior to undertaking a repairorcontinuing an installation cable, particularly telecommunications underwater cables. Secondly buoys are used as navigational markers and it is common practice for the cablelaying ship to carry marker buoys of various sizes and to connect the appropriate marker buoy to the cable end before release of the cable end into the water. Subsequently the cable end will be retrieved and connected to a further cable which could for example extend to the shore to a land-based terminal.

The size of buoy required depends on the. depth of water and the size and weight of the cable end and/or mooring lines.

An example of a known marker buoy is shown in Figure 1 ofthe drawings and shows somewhat schematically a marker buoy similarto ones that are already in use on board cable ships for marking the cable ends during cable laying operations at sea. The buoy comprises a float body 1 made of treated steel and formed of a hollow semi-spherical part 1 a welded to a lower hollow frusto-conical part lb which at its lower end incorporates a mooring eye frame 1c. The part 1a has eyes such as 2 carrying a line 3 attached to which is a recovery penant line having an eye.4 for a float tail. At the top of the buoy a tripod-like superstructure 5 is permanently secured which carries a warning light for navigation (not shown) and a bridle 6.The other end of the bridle 6 is connected to an egg link 7 which also carries a mooring line 8 and a rider 9 which passes through a bottom ring 10 and is connected to a slipping attachment 11.

For shallow water applications and cable ends the buoyancy of the float 1 would be of the order of 2 ton when immersed upto thejunctionline between the part 1 a and 1 b. For deeper water applications, larger buoys are provided for example having a buoyancy of around 6 tons and measuring about 9 ft, diameter and loft. high. A cable-laying or recovery ship will normally carry several such buoys of differing sizes for different conditions.

These known buoys are heavy and cumbersome and awkward to store. on the deck of a ship and. take up considerable valuable storage space.

According to the present invention there is provided a buoy comprising a support member, an elongate member extending from one side of the support member, panda float having a hole therein whereby it can be mounted on the elongate mem bey, the buoy being such-that the float will be retained on the elongate member and can be removed from the elongate member when desired.

In order that the invention can be clearly understood reference will now be made to Figure 2 of the accompanying drawings which shows somewhat schematically and partially in section, a marker buoy according to an embodiment of the present invention, and Figure 2A shows on an enlarged scale the slipping attachment.

Referring to Figure 2 the buoy comprises an elongate member in the form of a tubular mandrel 21 penetrating a hole 22b in a platform member in the form of a circular rigging support plate 22. A flange 21a prevents the mandrel falling through the hole 22b. Mounted on the tubular mandrel 21 are a number (five) of inflatable doughnut-shapedfloats such as 23. These are retained on the mandrel 21 by a removable retaining collar 24 having a clamping screw 24a. Also the floats 23 each squeeze the mandrel 21 when they are inflated, providing further resistance against the floats moving on the mandrel.

This may in itself be sufficient so that the collar 24 may not be necessary in some circumstances.

The rigging support plate 22 carries lifting eyes such as 25 and a tripod support frame 26 which carries buoy lights 27 and 28 and a staff 29. It also carries a slipping attachment 30 comprising a pivoted L-shaped part 31 and pivoted co-operating latch 32 (see Figure 2A). This slipping attachment releasably anchors the mooring chain (not illustrated).

It is envisaged that the lifting eyes and the slipping attachment will be manufactured as an integral part of the rigging support plate with the tripod support frame 26 as a detachable item. The support plate is made as light as possible with a radiused convex edge 22a to give it added rigidity. The tripod incorporates a tubular socket 26a which carries the staff 29 and also carries a platform 26b on which is mounted a detachable plate 27a carrying the lights 27.

One of the important features of this buoy is that the number of inflatable floats carried by the mandrel can be adjusted according to the requirement. In the embodiment described the outside diameter of each float, which is like a large rubbertyre, is about 5 ft., the diameter of the central bore is about 7" and the depth of each float is about 2 ft. when inflated.

Each float has a reasonably flat top 23a and bottom 23b. Each float, of the sizes stated above, will be capable of supporting approximately 1 ton with approximately 6" of it projecting above the water depending on the density of the water. Therefore where the- buoyancy requirement is of the order of 1 ton only one float need be assembled on the mandrel and the retaining collar 24 slid up the mandrel to maintain the single float in position against the rigging support plate 22. As the buoyancy requirements increase so additional floats can be mounted on the mandrel until the maximum buoyancy, which is five floats in this particular embodiment, is attained.

Only one size of float is required instead of perhaps three or four different buoy sizes with the prior art arrangement. Furthermore only one mandrel length is necessary whether one or five floats are used. Clearly the present invention is not limited to a buoy capable of supporting five floats; the mandrel could be designed to accommodate any number of floats according to requirements.

The floats would have a maximum and minimum pressure capacity and it is anticipated that the load carrying capacity could be varied by the pressure and hence the volume of water displaced. The floats are made of fabric-reinforced elastomeric or plastics material.

Where more than one float supports the buoy, if a leak occurs in one of the floats causing partial deflation then it may still be possible for the buoy to remain afloat under the buoyancy of the remaining floatation. This of course depends on the number of floats being used, the load being suspended and the extent of deflation.

The space in the storage hoid of a ship or on deck is always at a premium and this buoy has the advantage that the floats can be stored deflated and separate from the remainder of the buoy structure, and the mandrel and plate can also be dismantled and stored separately.

Although not shown the mooring line can be passed up the centre of the mandrel instead of lying up the side of the buoy as shown in Figure 1.

In the embodiment described the mandrel 21 has an internal bore of 7" diameter and its external diameter is between 74" and 8". It will be made of steel or glass fibre. The mooring line will pass up the centre bore of the mandrel and be anchored to the slipping attachment on the rigging support plate.

It is possible that the floats could be non-inflatable and made of for example expanded or foamed material which is watertight or rendered watertight by an outer covering.

Claims (12)

1. A buoy comprising a support member, an elongate member extending from one side of the support member, and a float having a hole therein whereby it can be mounted on the elongate member, the buoy being such that the float will be retained on the elongate member and can be removed from the elongate member when desired.

2. A buoy as claimed in claim 1, wherein the float is inflatable.

3. A buoy as claimed in claim 1 or claim 2, comprising several such floats.

4. A buoy as claimed in claim 1, claim 2 or claim 3, wherein the or each float is designed to embrace the elongate member such that friction therebetween will prevent or assist in preventing the float falling off the elongate member under the influence of gravity.

5. A float according to any preceding claim comprising a collar removably securable to the elongate member to retain the or each float thereon.

6. A buoy as claimed in any preceding claim, wherein the elongate member is a tube.

7. A buoy as claimed in any preceding claim, wherein the support member is a substantially flat plate except for a radiused edge or strengthening region.

8. A buoy as claimed in any preceding claim, wherein the support member has one or more lifting eyes secured thereto.

9. A buoy according to any preceding claim, comprising a support structure for supporting a staff and/or buoy lights, said structure being removably secured to the support member.

10. A buoy as claimed in any preceding claim, wherein the or each float has a buoyancy of approximately 1 ton.

11. A buoy as claimed in any preceding claim, wherein the support member has a hole therein and the elongate member fits in the hole, there being means to prevent the elongate member falling out of the hole.

12. A marker buoy substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.