An offshore drilling rig comprising a drill floor deck having a hole defining a first well center. The drilling rig may further include a first hoisting system configured for hoisting and lowering tubular equipment through the first well center. The drilling rig may further include first pipe handling equipment for presenting tubular equipment to the first hoisting system so as to allow the first hoisting system to hoist or lower the tubular equipment through the first well center. The drilling rig may include a mounting structure, separate from the first hoisting system for suspending suspendable auxiliary equipment from an elevated position above the drill floor deck, allowing the auxiliary equipment to be lowered or hoisted through the first well center; wherein the mounting structure is movable between a lower position for rigging up auxiliary equipment to the mounting structure, and an elevated position allowing lowering or hoisting of auxiliary equipment suspended from the mounting structure through the first well center.

A method for riser string handling on an offshore drilling vessel, the offshore drilling vessel including a multiple firing line hoist system, a riser tensioner system arranged in the second firing line, and a suspended riser transfer device. The method including the steps of lowering a riser string in the first firing line, and simultaneously assembling and preparing a riser tensioner system in the second firing line, wherein the riser hang-off assembly displaces the riser string, leaving the top end of the riser string exposed, from the first firing line to the second firing line to be connected to the riser tensioner system.

An offshore drilling vessel includes a main deck, a moonpool a firing line hoist system having a tower, a BOP transport system and a pivotally supported U-shaped working deck. The U-shaped working deck can be pivoted between an active position, in which it extends in a substantially horizontal direction such that it covers a portion of the moonpool, and a non-active position, in which it extends in a substantially vertical direction such that it provides room for a BOP to be moved by the BOP transport system from a storage position adjacent the moonpool into a launch position above the moonpool, in which launch position the BOP is located between the tower and the working deck.

Offshore drilling system for performing subsea wellbore related activities including a drilling vessel, with a floating hull subjected to heave motion. A main cable heave compensation sheave is provided for heave compensation of a travelling block. A connection cable heave compensation sheave is provided between a connection cable winch and a top sheave assembly supported on the hull of the vessel in or above the moonpool. The main cable heave compensation cable sheave and the connection cable heave compensation sheave are mechanically interconnected so as to allow for synchronous motion thereof.

An offshore drilling vessel includes a floating hull subjected to heave motion. The hull includes a moonpool and a drilling tower near the moonpool. A drilling tubulars storage rack is provided for storage of drilling tubulars. The vessel includes a heave motion compensation support that is adapted to support a slip device whilst performing heave compensation motion relative to the heaving motion of the vessel. A racking device is provided with a heave motion synchronization system that is adapted to bring a tubular retrieved from the storage rack in heave motion into a vertical motion that is synchronous with the heave compensation motion of the string slip device. The racking device includes vertical rails and at least two separate motion arm assemblies mounted on said vertical rails. Each separate motion arm assembly includes its own vertical drive which is electrically connected to the heave motion synchronization system.