Monohull Drilling Vessel Deck Configuration for Strength and Stability
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Solution Overview
Problem
Existing monohull offshore drilling vessels face challenges in optimizing the balance between weight and strength, with equipment storage configurations that do not allow for efficient handling and movement between decks, leading to limitations in vessel size and operational efficiency.
Innovation Solution
The design elevates the upper deck to be flush with the drill floor, stores heavy equipment below the upper deck to lower the mass center of gravity, and increases the moonpool wall height to enhance vessel strength, allowing for easier movement and storage of drilling tubulars and accessories, while maintaining a compact geometry and reducing power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If equipment is stored on deck in prior art vessels, then equipment accessibility is improved, but vessel strength around the moonpool is reduced and center of gravity is elevated
Solution Approach 1:
The patent transitions equipment storage from the horizontal deck surface to the vertical space below the upper deck. By utilizing the previously underutilized volume beneath the upper deck for equipment storage, the design achieves both improved vessel strength (through higher upper deck positioning and increased moonpool wall height) and maintained equipment accessibility (via elevators and ramps connecting to working decks). This dimensional reorganization resolves the contradiction between deck-space accessibility and structural strength.
2Ease of operation
If upper deck is elevated to be flush with drill floor, then movement of persons and objects is simplified, but construction complexity increases
Solution Approach 1:
The patent merges the upper deck and drill floor into a single continuous surface at the same elevation. By eliminating the vertical separation and transition structures (ramps, elevators, or hatches) between these two decks, the design simplifies movement for personnel and equipment while reducing construction complexity. The drilling equipment and tubular storage are integrated into this unified deck level, creating a streamlined operational platform.
3Strength
If moonpool wall height is increased to enhance vessel strength, then bending moment of deck is reduced, but displacement and fuel consumption increase
Solution Approach 1:
The patent implements preliminary structural reinforcement by increasing moonpool wall height and positioning the upper deck higher relative to the moonpool. This preemptive strengthening of the hull structure around the moonpool reduces bending moments and enhances vessel strength before operational loads are applied, thereby preventing the need for heavier compensatory structures that would increase displacement and fuel consumption.
4Stability of the object's composition
If drilling equipment is stored in hull below upper deck, then center of gravity is lowered improving stability, but equipment accessibility and handling becomes more difficult
Solution Approach 1:
The patent introduces intermediary transport mechanisms (elevators and ramps) that facilitate equipment movement between the storage area below the upper deck and the working decks. These intermediaries bridge the vertical gap, enabling efficient equipment handling and accessibility while preserving the stability benefits of low-center-of-gravity storage configuration.
Data Source
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AI summary
The present invention relates to a monohull offshore drilling vessel comprising a hull with a bow and a stern and a moonpool extending through the hull, the hull having an upper deck. A firing line hoist system comprising a mast is mounted on the hull. A drill floor is provided at a firing line side of the mast, which covers a portion of the moonpool while the firing line extends through an opening in said drill floor. Furthermore marine equipment and drilling equipment for performing auxiliary operations for the drilling or drilling related operations is provided, which equipment is mainly provided in the hull of the vessel below the upper deck. According to the invention, the drill floor is flush with the upper deck