Vessel Hull Stern Design Reducing Wave Slamming
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Solution Overview
Problem
Existing ocean-going vessels experience significant discomfort and instability due to wave slamming and excessive pitching, particularly in offshore and subsea operations, where conventional hull designs exacerbate these issues by increasing displacement and turbulence, leading to high drag and fuel consumption.
Innovation Solution
A displacement vessel design featuring a transversely symmetrical hull with a stern that extends below the waterline, forming an acute angle and a convex shape to reduce displacement, combined with a foreship design that decreases buoyancy, resulting in reduced wave impact loads, pitching, and drag, while maintaining stability under various wave directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stern is raised above the design waterline to obtain a smooth transition from below to above water, then the hull form becomes simpler to manufacture, but the displacement of the rear end increases, resulting in high slamming impact and wave impact pressure loads
Solution Approach 1:
Instead of raising the stern above the waterline to simplify manufacturing, the patent inverts the approach by extending the stern below the design waterline. This creates a submerged transom configuration that reduces the wetted surface area and displacement at the rear end, thereby reducing slamming impact and wave impact pressure loads while maintaining manufacturing simplicity through the use of a flat transom structure.
Solution Approach 2:
The patent changes the key parameter of stern position from above-waterline to below-waterline. This parameter change fundamentally alters the interaction between the stern and waves, reducing the impact area and displacement volume at the rear end, which directly addresses the harmful slamming and wave impact effects.
2Object-affected harmful factors
If the stern is extended below the waterline forming an acute angle to decrease displacement, then wave impact loads are reduced, but the hull shape becomes more complex
Solution Approach 1:
The patent segments the stern structure into distinct zones: a submerged transom section below the design waterline forming an acute angle, and an above-waterline section with a different configuration. This segmentation allows each zone to perform its specific function - the submerged portion reduces wave impact while the upper portion maintains structural integrity and simplicity.
Solution Approach 2:
The patent applies local quality by creating a specific acute-angled configuration only in the critical submerged transom region where wave impact occurs, while the rest of the hull maintains conventional simple forms. This localized complexity is applied precisely where needed to reduce wave impact loads without making the entire hull complex.
3Ease of manufacture
If a flat upright stern transverse to the hull symmetry line is used for cost and simplicity, then manufacturing is easier, but the displacement of the rear end greatly increases, resulting in high pitching and slamming impacts
Solution Approach 1:
Instead of using a conventional flat upright stern that is transverse to the hull symmetry line, the patent inverts the design by creating a stern that extends below the waterline with an acute angle configuration. This inverted approach maintains the simplicity of a flat transom structure for easy manufacturing while fundamentally changing the hydrodynamic behavior to reduce pitching and slamming impacts.
Solution Approach 2:
The patent changes the stern configuration parameters from a conventional flat upright transverse design to a below-waterline extended design with acute angles. This parameter change reduces the effective displacement and wetted surface area at the rear end, thereby reducing pitching moments and slamming impacts while keeping the structure simple to manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances stability and comfort by minimizing wave impact, reducing fuel consumption, and allowing vessels to operate effectively in low to high wave conditions without excessive pitching or surfing, while also being cost-effective and easier to manufacture.
Implementation Method 1
a stern of the vessel extend below a design waterline, and wherein opposite side surfaces of the stern when seen in an opposite direction of the vessels primary sailing direction forms an acute angle under and above the design waterline configured to decrease the vessels displacement in the rear end
Implementation Method 2
This means that the so-called transom, the area of the hull separating the hull from the water is mostly generally undefined due to the nature of the waves through which the vessel propagates. This is a fact, which technical has an effect of increasing turbulence in an area or volume behind the vessel
Data Source
AI summary
This relates to vessels in general, but in particular to displacement vessels designed to be exposed from low to medium to high waves. Both for comfort of persons, animals or fragile goods, steady sailing is preferred, without causing the waves slamming in on the vessel hull or excessive pitching of the vessel. This is also the case for service and supply vessels performing operations in relation to offshore or subsea installations. To obtain a solution to the aforementioned issues the present invention provides a vessel, wherein a stern of the vessel extend below a design waterline (Tdwl), and wherein opposite side surfaces of the stern, when seen in an opposite direction of the vessels primary sailing direction, form an acute angle under and above the design waterline (Tdwl) to decrease the vessels displacement in the rear end and are adjoined along at a line of symmetry forming a stern centerline.