1. Field of the Invention
This invention generally relates to anchoring arrangements for floating structures and more particularly to anchoring arrangements for floating structures such as converted tankers.
2. Description of the Prior Art
The traditional anchoring arrangements comprising any of the known types of anchors cater to the anchoring requirements of seagoing vessels and other floating structures, for example, tankers, which are either at a dock or a harbor. Occasionally, certain conventional anchoring arrangements are used to anchor vessels in the open sea. However, it is known that conventional anchoring will not be very effective if the floating structure or vessel is in high seas, especially when it is required to connect a transfer hose or an underwater transfer tube carrying a fluid, for example oil or gas, to the floating vessel. Even with anchoring, a certain degree of shifting of the floating structure, or even a certain degree of rotation of the floating structure, might occur in high seas. At least one consequence of such shifting or rotation is that the transfer hose, for example, tends to get damaged or even disconnected, causing serious consequences. The problem is especially serious in the case of ocean vessels such as converted tankers in high seas wherein there is need for having at least a transfer tube constantly connected to the tanker through the ocean water, invariably to the sea bed or the shore or another vessel. Certain structural arrangements have been used heretofore to cater to the needs of stably and permanently anchoring converted tankers, simultaneously making provision for a transfer pipe or tube connected between the tanker and the sea bed. However, prior art arrangements have always required a significant mass of steel to fabricate the underwater anchoring structure, consequently rendering the equipment expensive from the poin the view of installation and maintenance. Furthermore, it has been found that it is desirable to provide an underwater means which permits relative rotary movement between the tanker superstructure and the anchoring arrangement to make a provision for oscillatory and rotary swaying movements of the tanker superstructure in high seas. Preferably, the underwater means should have a pivot bearing mechanism to easily permit such movement. Also, it is desirable that there should be easy access for maintenance personnel to reach at least part of the bearing mechanism to attend to maintenance and replacement work, preferably in a dry atmosphere. Such facilities are not available in any known prior art anchoring arrangement.
There is, therefore, a great need for an anchoring arrangement devoid of the disadvantages and limitations of prior art and including the more desirable features which are discussed above.
There is also a great need for an anchoring and transfer system which is low in cost and can be installed in a converted tanker using only minimum labor, wherein only a small working area is required at the anchorage. There is also a need for an anchoring arrangement including a transfer system wherein there is excellent accessibility to the anchoring apparatus, and wherein the fluid transfer system is weatherproof, and protected against collision.