Ships – Towing or pushing – Coupling means
Patent
1995-07-31
1997-04-01
Avila, Stephen
Ships
Towing or pushing
Coupling means
114253, B63B 2104
Patent
active
056156308
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a stern arrangement for a ship.
BACKGROUND OF THE INVENTION
There are occasions when a ship is towed by another ship. Typically it happens when an icebreaker tows a ship. Towing by icebreaker must be done so that the bow of the ship to be towed has been pulled tightly into the close contact with the stern of the icebreaker. The ship to be towed will be kept in the right place by a towing winch located aboard on the icebreaker. The winch pulls strongly at the wire rope the bow of the towed ship against the stern of the icebreaker during the towing operation.
For towing purposes the stern of the icebreaker must be formed in a special way. At the stern of the icebreaker there is an inwards curved towing notch which makes possible to tow another vessel. Only when equipped with this notch it is possible for the icebreaker to tow a ship in the way that the bow of the ship to be towed is pressed directly towards the stern of the icebreaker.
There are also other kind of special needs for the stern form of a ship. In open water for example the anchor handling and the cable laying operations require different kind of stern forming. At the stern of a supply vessel there must not be any formed towing notches. Instead of that it is on the contrary required that the stern of the supply vessel is straight and the stern roller is installed. In the supply vessel the different kind of hoisting operations are done over the transom with a winch or crane.
The special requirements said above cause that a ship constructed for one purpose can not be used for another purpose. The same ship can not be used for the towing in winter and for supply operations in summer. The requirements for the stern shape and the stern structure are so different in winter operations and respectively in summer operations that it is not possible to build a fixed structure which would be suitable for the both purposes.
The problem with icebreakers, however, is their short operating time in winter. It should be able to use icebreakers also in the summertime in open water. Correspondingly the supply vessel can not be used for towing in wintertime because of its unsuitable stern construction.
SUMMARY OF THE INVENTION
The object of the present invention is to eliminate the above mentioned problem. This purpose will be achieved so that according to the invention the stern of the ship is made modifiable or convertible for at least two different purposes, by moving or by replacing at least a part of the stern.
PREFERRED EMBODIMENTS OF THE INVENTION
According to a preferred embodiment of the invention the stern of the ship is convertible to be a towing notch or to be equipped with a stern roller.
The preferred embodiment of the invention provides the ship which is equipped with a structure which enables a towing notch in wintertime and a stern roller in the summertime. Combining these two possibilities it is for the first time possible to make a multipurpose icebreaker which is suitable both for winter operations and also for summer operations.
Besides the supply operations in summer the suitable tasks for a multipurpose icebreaker would be for example towing, anchor handling, cable laying, flexible pipe laying and supply operations. These kind of operations are usually operated by a special supply ship which has the straight stern and which is also equipped with a stern roller. With a supply ship it is possible to do different kind of hoisting operations over the transom with a winch or crane. Typical operations are anchor handling and hoisting of umbilicals and other offshore equipments.
According to an embodiment of the invention at the stern of the ship there is at least one movable part which moves out in the way that a towing notch or a stern roller is available.
An other embodiment of the invention the stern of the ship is equipped either with a fixed towing notch or with a fixed stern roller section, and the other one of them is movable or removable in the way that the towing notch or the stern roller is availab
REFERENCES:
patent: 3735722 (1973-05-01), Hooper et al.
patent: 3866555 (1975-02-01), Korkut
patent: 3892386 (1975-07-01), Hogan
patent: 3977352 (1976-08-01), Pran et al.
Eronen Harri
Harjula Arjo
Avila Stephen
Finnyards Oy
Kubovcik Ronald J.
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