Mooring system for floating drilling vessels

A mooring system for maintaining a ship shape drilling vessel within alignment limits while drilling a well from the vessel in the subsurface ground below it comprising,

• a plurality of mooring chains, at least one extending from each side fore and aft the vessel,
• an anchor on each mooring chain for anchoring the anchor to the subsurface ground,
• an electric motor driven wildcat for each of the anchor chains,
• a brake including a brake band for each wildcat,
• a chain stopper for each anchor chain operable to lock the chain in position,
• a fairlead for each chain at the edge of the vessel,
• each anchor chain extending from one each of the wildcats through one each of the chain stoppers and the fairleads,
• means for sensing load on the electric motor while hauling in the anchor chain,
• a first sensor on the brake band sensing load thereon,
• a second sensor on the chain stopper sensing load thereon,
• a counter on each fairlead arranged to count links of each of the anchor chains as they are payed out and hauled in through the fairlead,
• load and counter display means, and
• means for transmitting the load sensed by the means sensing the load on the electric motors, the first and second sensors, and the count of the counters to the display means,
• whereby the anchor chains can be let out and hauled in based on the loads sensed and count made thereby maintaining the vessel within the alignment limits and the vessel can be warped into the sea.

A windlass for paying out and hauling in a mooring line comprising,

• a wildcat,
• an electric motor,
• means operably connecting the electric motor with the wildcat including clutch means arranged to disengage the electric motor from the wildcat on paying out the mooring line,
• the means including,
• at least one driven shaft, and
• braking means on the driven shaft operable to control its rate of rotation and thereby the rotation of the wildcat.

A chain stopper for stopping and locking in position an anchor chain comprising,

• a body through which the anchor chain passes
• an eccentric shaft,
• means journaling the eccentric shaft in the body and arranged to free the shaft on shifting it axially,
• a pawl secured to the eccentric shaft,
• means to move the pawl into engagement with links of the anchor chain and to lock it into engagement therewith and to move the pawl out of engagement therewith to free the anchor chain for movement,
• shifting the eccentric shaft axially freeing the shaft and the pawl to move with the anchor chain when under load.

A chain stopper for stopping and locking in position an anchor chain comprising,

• a body through which the anchor chain passes,
• an eccentric shaft,
• means journaling the shaft in the body and arranged to free the shaft on shifting the shaft axially,
• a pawl secured to the eccentric shaft,
• the pawl having a surface for engaging links of the anchor chain, which surface extends transversely at least as far as the width of the links and has transversely-extending inwardly tapered faces extending from the central portion which substantially mate with the links they engage,
• means to move the pawl into engagement with the links of the anchor chain thereby locking it into position and to move the pawl out of engagement therewith to free the anchor chain for movement through the body,
• means to impact an end of the eccentric shaft to shift it axially, and
• means for remotely and selectively actuating the means to impact an end of the eccentric shaft thereby shifting it axially and freeing it and the pawl to move with the anchor chain when under load.