Inboard Extended Column Semi-Submersible Hull Design
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Solution Overview
Problem
Semi-submersibles in the oil and gas industry face hydrodynamic performance issues due to the spacing between columns and pontoons, which affects metacentric height and increases the complexity, size, and weight of the topsides, limiting the hydrodynamic performance and increasing costs.
Innovation Solution
The design incorporates columns with a cross section featuring a rectangular first portion and an inboard-extending triangular second portion, allowing for wider pontoon spacing without increasing support point spacing, thereby improving hydrodynamic performance while reducing the size and weight of the topsides and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the spacing between columns is reduced, then the metacentric height is reduced and topsides size/weight increase, but the pontoon spacing is reduced which negatively affects hydrodynamic performance
Solution Approach 1:
The column cross-section transitions from a conventional square shape to a pentagonal shape by adding a second triangular portion that extends inboard. This dimensional modification in the cross-sectional geometry allows the column to provide enhanced lateral support and stability without requiring reduced spacing between columns, thereby maintaining metacentric height while improving hydrodynamic performance through increased pontoon spacing.
2Device complexity
If the spacing between sides of the pontoon is increased, then the hydrodynamic performance improves, but the spacing is limited by the column spacing which is constrained by topsides size, weight, and cost
Solution Approach 1:
By modifying the column cross-section to include an inboard-extending triangular portion, the design enables increased pontoon spacing without proportionally increasing topsides weight. The optimized geometry provides enhanced structural efficiency, allowing the hull to achieve improved hydrodynamic performance through wider pontoon spacing while the column configuration maintains adequate support with reduced material requirements.
3Area of stationary object
If the column cross section is modified to extend inboard, then the pontoon spacing can be widened without increasing support point spacing, but the column geometry becomes more complex
Solution Approach 1:
The column cross-section is segmented into distinct geometric portions: a first rectangular portion providing the primary structural framework and a second triangular portion extending inboard. This segmentation allows each portion to fulfill specific functional requirements - the rectangular portion maintains structural integrity while the triangular portion enables widened pontoon spacing - thereby achieving increased spacing without proportionally increasing overall column complexity.
Solution Approach 2:
The column design merges the rectangular and triangular portions into a unified pentagonal cross-section that functions as an integrated structural element. This combination allows the column to simultaneously provide lateral support through the rectangular portion and enable widened pontoon spacing through the inboard-extending triangular portion, achieving multiple objectives within a single geometric form rather than requiring separate structural components.
Data Source
AI summary
Aspects of the present disclosure relate generally to apparatus for semi-submersibles, including hulls of semi-submersibles. In one implementation, a hull for a semi-submersible includes a pontoon having one or more sides, and a plurality of columns extending upwards from the pontoon and configured to support a topsides. Each one of the plurality of columns has a cross section that is in a plane perpendicular to an axial centerline of the respective one of the plurality of columns. The cross section includes a first portion being rectangular in shape and a second portion being triangular in shape and having an apex that extends inboard from the first portion.