EP0414320A1

EP0414320A1 - Tilting life raft davit

Info

Publication number: EP0414320A1
Application number: EP90202236A
Authority: EP
Inventors: Jacobus Van Drunen
Original assignee: SCHAT-DAVIT Co BV
Current assignee: SCHAT-DAVIT Co BV
Priority date: 1989-08-21
Filing date: 1990-08-20
Publication date: 1991-02-27
Also published as: NO903672D0; NO903672L; NL8902104A; FI904146A0

Abstract

A davit movable relative to a board or a side of a ship or offshore rig between an inboard rest position and an outboard operative position for lowering a life raft, in particular an inflatable raft, by means of a winch through gravity. For this purpose according to the invention, the davit comprises a davit arm (2) mounted on a shaft (5) located inwardly of said board or side, for pivoting movement between said inboard position and said outboard position, and arranged so that in the inboard position, the centre of gravity of the davit arm (2) is located outboard of said shaft (5).

Description

This invention relates to a davit movable relative to a board or a side of a ship or offshore rig between an inboard rest position and an outboard operative position for lowering a life raft, in particular an inflatable raft, by means of a winch.
With a height of fall of more than 4.5 m, life rafts are required by regulations to be lowered by means of a davit. All known life raft davits are moved into the outboard position by means of some drive, mechanical, hydraulic or electric, to lower successive rafts.
It is an object of the present invention to provide a life raft davit, in particular for inflatable life rafts, which does not require a driving device for moving the davit into its outboard position.
To this effect, according to the present invention, the davit comprises a davit arm mounted on a shaft located inwardly of said board or side, for pivoting movement between said inboard position and said outboard position, and arranged so that in the inboard position, the centre of gravity of the davit arm is located outboard of said shaft.
The invention is based on the insight that, by selecting a tilting davit arm with this location of its centre of gravity, the arm will always be loaded so as to be biased to move to its outboard position, so that it can tilt through gravity, and driving devices hitherto required for this purpose can be done without. As a consequence, the davit is not only simpler, but also more reliable in operation.
In a preferred embodiment of the invention, the davit arm has the form of a bell crank lever journalled on said shaft at the free end of one of the lever arms.
In the rest position, both lever arms are in an inboard position, and in the operative position one lever arm rests on the board side deck of a ship or offshore structure, while the other lever arm extends in an obliquely upward outboard position.
According to the invention, in the inboard position, the davit arm rests through a support on a stand, which support is removable from the tilting path of the davit arm to its outboard position.
In the tilting life raft davit according to the invention, the davit arm is locked in its inboard position by the removable support, so that the winch and the winch cable are unloaded. Unlocking is preferable done by tensioning the winch rope, which will also prevent or remove any slack in the rope, and after unlocking the pivot arm can be tilted outboard in a controlled manner for lowering an inflatable life raft.
Subsequently, an inflatable raft, stored in a container, is secured to a self-releasing hook, and the container is opened in a suitable way. The inflated raft is then hanging next to the side of the ship or offshore structure in such a position that it can be manned. The raft is paid out by a person at the davit. Uncoupling is done from the lowered raft, for which use is made of an automatic release hook. The last man to leave the ship or offshore structure can operate the winch to allow the rope to pay off, through remote control from the raft hanging next to the board or side, so that the raft is lowered through gravity.
One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which

Fig. 1 is a side-elevational view of the davit according to the present invention; and
Fig. 2 is a left-hand end view of the davit of Fig. 1.

Referring to the drawings, a davit (namely, a so-called P.A.R = Pivoting Arm Raft Davit) is mounted on the board or side 1 of a ship or offshore rig. The davit comprises an arm 2 in the form of a bell crank lever with a shorter lever arm 3 and a longer lever arm 4. The davit arm is mounted for pivoting movement on a shaft 5 and, in the rest position shown in solid lines in Fig. 1, rests on a support pin 6 in a stand 7. There is further shown a winch 8, the rope 9 of which is passed over the head 10 of davit arm 2, and is equipped with a self-releasing hook 11, which in the rest position of the davit arm is positioned within arm's reach on the shorter lever arm 3 of davit arm 2, and is locked by means of a hook 14.
To move davit arm 2 from the rest position into the operative position, shown in dash-dot lines in Fig. 1, rope 9 is pulled by operating winch 8 by hand. As the self-release hook 11 is locked relative to lever arm 3, hoisting with the winch results in davit arm 2 being lifted off pin 6, so that pin 6 can be removed from stand 7. Subsequently, the davit arm 2 can be tilted to the outboard position about shaft 5 through gravity (luffing) by releasing the winch brake.
A container not shown with an inflatable life raft 12 is secured to the self-release hook 11, and put overboard while the container is opened. The inflated raft occupies the position shown in dot-dash outline in Fig. 1 next to side 1, and can be manned and lowered by giving slack to winch rope 9. After the launching of raft 12, hook 11 can be uncoupled, which is a simple matter with a so-called self-release hook, which can thereafter rapidly be raised, and the procedure described above can be repeated. When the last man has boarded a raft, he takes along a remote control line 13 to operate winch 8 from raft 12 to give slack, so that the last raft, too can be lowered through gravity.

Claims

1. A davit movable relative to a board or a side of a ship or offshore rig between an inboard rest position and an outboard operative position for lowering a life raft, in particular an inflatable raft, by means of a winch, characterized in that the davit comprises a davit arm (2) mounted on a shaft (5) located inwardly of said board or side, for pivoting movement between said inboard position and said outboard position, and arranged so that in the inboard position, the centre of gravity of the davit arm (2) is located outboard of said shaft (5).

2. A tilting life-raft davit as claimed in claim 1, characterized in that the davit arm has the form of a bell crank lever journalled on said shaft (5) at the free end of one of the lever arms (3).

3. A tilting life-raft davit as claimed in claim 2, characterized in that, in the inboard position, the davit arm (2) rests through a support(6) on a stand (7), which support (6) is removable from the tilting path of the davit arm (2) to its outboard position.