US 4,231,313 AGranted

Stabilizing system on a semi-submersible crane vessel

AssigneeVaritrac AG

InventorsPieter S. Heerema, Alexandre Horowitz, Henricus P. Willemsen

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Abstract

A vessel comprising a pair of laterally spaced elongated buoyancy hulls and vertically mounted thereon a plurality of hollow columns, distributed around the outer circumferential area of the vessel and supporting a work platform above the water level when the hulls are submerged, the hulls containing water ballast compartments. The platform supports one or more heavy duty cranes, adapted for outboard handling of loads. At the lower end of the columns, air chambers are provided in open connection with the surrounding water at their bottom ends. At their upper ends these chambers have air valves for discharging air from and supplying air to the chambers selectively controlled by directions from a computer which is added to the crane operating device. Sensors and other measuring instruments are provided, such as, for continuously gauging the water levels in the different air compartments, the air pressure therein and the water pressure at the exit of these compartments to the open water, the top and swivel angles of the cranes, the hilt of the vessel and the weight of the crane loads. The data measured by these instruments are introduced into the computer which controls the regulator air valves and thereby the water levels in the different air chambers whereby the vessel is maintained substantially on an even keel during load handling by the cranes.

Claims7

Dependent claims

A semi-submersible crane vessel comprising a platform, a plurality of vertical hollow columns supporting the platform, said columns being distributed along a circumferential outer region of the vessel, submerged bouyancy hulls supporting said columns such that the platform is above water level, and a stabilizing system for stabilizing the vessel with respect to outboard handling of loads by at least one crane on the vessel, said stabilizing system comprising ballast chambers in said bouyancy hulls, valve means for selectively admitting surrounding water into said chambers, said chambers comprising (a) air chambers at the lower ends of said columns at the level of said submerged buoyancy hulls;

(b) said air chambers having a top closure below the level of the water surrounding said submerged buoyancy hulls, a bottom connection in communication with the surrounding water and vertical air conduits extending upwardly from said chambers for connecting the latter to ambient atmosphere;
(c) means for controlling said valves for admission of desired amounts of water into said air chambers during handling of a crane load in dependence on the weight of said loads and the position of said loads with respect to said vessel and measuring means including gauging means for measuring the water level in each said air chamber, said gauging means including an air pressure sensor for each of said air chambers and a water pressure sensor at the exit of each said chamber to the surrounding water, the difference between said sensed pressures being indicative of the water level in each said first air chamber.

(b) said air chambers having a top closure below the level of the water surrounding said submerged buoyancy hulls, a bottom connection in communication with the surrounding water and vertical air conduits extending upwardly from said chambers for connecting the latter to ambient atmosphere;
(c) means for controlling said valves for admission of desired amounts of water into said air chambers during handling of a crane load in dependence on the weight of said loads and the position of said loads with respect to said vessel, vertical partition walls in said first air chamber dividing the same into compartments, said vertical partition walls extending from a central zone of each of said first chambers to outer chamber walls, each of said compartments being provided with one of said air valves and with pressure sensor means, said pressure sensor means comprising a water pressure sensor common for said air compartments arranged at the bottom end of a tube formed in the center of said air chamber.

Dependencies are inferred from the claim text.

Facts

Application: 05/913,608Filed 7 Jun 1978 · continuation
Priority: NL 760171219 Feb 1976
Granted: 4 Nov 1980
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

B63B 43/06
By improving stability: using ballast tanks
B63B 39/03
To decrease vessel movements by displacement of masses: by transferring liquids
B66C 23/52
Mounted on road or rail vehicles; Manually-movable jib-cranes for use in workshops; Floating cranes: floating cranes
B66C 23/53
Floating cranes: including counterweight or means to compensate for list, trim, or skew of the vessel or platform